technical exam flashcards

Question

Compare LCA with Eco Audit for a kettle

Answer 1

LCA (life cycle analysis) provides outputs under headings of * resource consumption (including materials, energy, water), * emissions (including various gases, particulates), * and impact assessment (including ozone depletion, global warming, acidification, human toxicity). These different factors cannot readily be combined, so are usually left as separate datapoints. There is currently no single method for conducting an LCA, but ISO14040 is an international standard which sets out a framework. * It is a systematic way of analysing the impact of an activity or producing a product. * It considers all phases of the lifecycle. * It is useful for comparing the impacts of comparable activities (e.g. two ways of making a product). LCA is expensive, time-consuming, does have subjective elements, and is retrospective (normally too late to influence design). For the kettle, the outputs will include all those noted above (maybe in subcategories as well). It may be noted that most of the impact comes from the use phase. Eco-audit provides a single measure of impact, which may be energy or CO2. This is generated under the headings of * Material, Manufacture, Transport, Use and Disposal and usually presented as a bar chart. In addition a summary is generated showing detailed breakdown, life phase energies, life carbon footprints. * Eco-audit provides a quick and approximate measure of one aspect of environmental impact. * Does not take full account of other eco factors which are included in full LCA. The following factors may be noted: * gaseous emissions (e.g. SOX, NOX), particulates, ozone depletion potential, acidification potential, human toxicity potential. * Water use is another big factor which may increasingly become a show-stopper. It identifies the dominant life phase so allowing a targeted approach to reducing environmental impact. It is done early enough in the design process to influence design. For the kettle, the use phase dominates, so the biggest improvement may be made by improving thermal insulation of the kettle.

Answer 2

Outputs can be generated under nine environmental themes (students were not expected to remember details for these, but they are stated here for completeness): * Abiotic depletion potential; * Energy depletion potential; * Global warming potential; * Ozone depletion potential; * aquatic/terrestrial ecotoxicity; * acidification potential; * human toxicity; * photochemical oxidant creation; * nitrification potential. All have different metrics, so combining them is not straightforward. Most studies choose only some of the headings, and tend to keep the figures separate under them. Assessment of impact therefore requires some judgment, such as which metrics are most important. The choice of system boundaries is crucially important in any LCA. There is some flexibility about how this is done, so it is important that similar system boundary choices have been made when making comparisons between different LCAs. Similar care should be taken over allocation and choice of functional unit.

Answer 3

Environmental impacts: * Product life increased by orders of magnitude, so (simplistically) reduces wastage. * But the lengthening of the supply chain promotes globalisation of food production, with both positive and negative environmental consequences (factors include **transport, agricultural policies and impacts**). * The complexity of packaging material may in some cases be increased if a barrier function is included (e.g. as an additional polymer layer in cheese packaging, or with metallised films), reducing recyclability. * Considering packaged food as a whole, the environmental impact of the food production hugely dominates the total impact. * So the impact of the packaging itself is normally considerably less than 5% of the total impact, and any end-of-life considerations are (in terms of energy or carbon footprint) negligible.

Answer 4

* A system boundary is used to define what should be included for a particular environmental analysis. For this case, the following factors should be considered: Packaging: * Material production, manufacturing process, **transport between different stages**. End-of-life disposal. Supply chain issues: * The weight and volume of the packaging and how it affects the density with which the product can be packed for transport. The analysis is of the packaging, so the production of the product being packaged (cheese) is outside the boundary. Nevertheless, the effectiveness of the packaging has implications for the shelf-life (lifetime) of the product.

Answer 5

User inputs include * Bill of materials, * shaping processes, * transport needs, * duty cycle. The Eco database is used to generate * **embodied energies**, * **process energies**, * **CO2 footprints**, * **unit transport energies** etc. The eco-audit can be facilitated using CES. Assumptions may typically include details of the materials used. Outputs include a bar-chart showing impact of the four lifecycle phases: material, manufacture, transport and use, plus end-of-life. The analysis should be used to identify the phase with the greatest impact, and to focus on this for action. Additional factors: * In assessing the wider environmental consequences of food packaging, the domination of the food production aspect should be remembered. * Not specifically mentioned are the factors associated with the function of food packaging in reducing food wastage, including the barrier function described under (a) (ii).

Answer 6

LCA: * Define goal and scope of study. * Define * the functions of the product system, * functional unit, * boundaries and * product system. * Define methodology, assumptions and limitations. * Perform inventory analysis. * Assign environmental impacts of product system. * Interpret results. Eco-audit: User inputs include * Bill of materials, * shaping processes, * transport needs, * duty cycle. The Eco database is used to generate embodied energies, process energies, CO2 footprints, unit transport energies etc.

Answer 7

The system boundary defines what is included in the LCA. Although the protocol is documented, it is subject to interpretation. For biodiesel, there will be variation in the extent to which growing of the crops is included, and how the agricultural systems are treated. Allocation: Any process involves many systems, which are not independent. Allocation is the appropriate distribution of responsibility for resource consumption, emissions and wastes from processes.

Answer 8

* The eco-audit will generate a bar chart in which the dominant phase is the duty cycle, followed by the material. * Increasing the operating efficiency of the fridge to reduce energy consumption will be the main recommendation. * This will be achieved primarily by improving thermal insulation, though note that this will also increase the impact of the Materials phase. * There may be scope within the design of the fridge for reducing the heat transfer when the fridge door is open – e.g. compartments in the fridge to retain the cold. * Optimising the efficiency of the cooling mechanism is something else to be done – but there may not be much improvement possible there. * There may be scope for encouraging good behaviour by incorporating alarms that sound if the fridge door is left open.

Answer 9

Risk Present when managers know the possible outcomes of a particular course of action and can assign probabilities to them Uncertainty The future is unknown, and probabilities cannot be given for outcomes

Answer 10

* Actual decisions made depend on the willingness to accept risk * Expected utility theory allows for different attitudes towards risk-taking in decision making * Managers are assumed to derive utility from earning profits * Managers make risky decisions in a way that maximises expected utility of the profit outcomes * Utility function measures utility associated with a particular level of profit * Index to measure level of utility received for a given amount of earned profit * Managers attitude toward risk * Determined by the manager’s marginal utility of profit * Marginal utility (slope of utility curve) determines attitude towards risk

Answer 11

You are risk averse with respect to a gamble if you prefer the expected value of the gamble with certainty to the gamble itself. You are risk averse if the expected value is greater than the certainty equivalent.

Answer 12

The calling population * The population which customers/jobs originate * The size can be finite or infinite (the latter is most common) * Can be homogeneous (only one type of customer/job) or heterogeneous The arrival process * Determines how, when and where customer/jobs arrive to system * The important characteristic is the customers/jobs inter arrival times * Correct specification of the arrival process requires data collection of interarrival times and statistical analysis The queue configuration * Specifies the number of queues * Their location * Effect on customer behaviour (balking or reneging) * The max size the queue can hold (infinite/finite capacity) Service mechanism * Can involve one or several service facilities with one or several parallel service channelsThe service provided by a server is characterised by its service time * Typically involves data gathering and statistical analysis * Most analytical queuing models are based on the assumption of exponentially distributed service times The queue discipline * Specifies the order by which jobs in the queue are served * Most common principle is FIFO * Other rules are: LIFO, SPIT, EDD * Can entail prioritisation based on customer type Examples of world queuing systems: Commercial queuing systems * Commercial organisations serving external customers * E.g. dentist, bank, ATM, petrol stations, plumber, garage … Transportation service systems * Vehicles are customers or servers * E.g. vehicles waiting at toll stations and traffic lights, trucks or ships waiting to be loaded, taxi cabs, fire engines, lifts and buses Business – internal service systems * Customers receiving service are internal to the organisation providing the service * E.g. inspection stations, conveyor belts, computer support … Social service systems * E.g. ER at a hospital, waiting lists for organ transplants, waiting lists for primary school places

Answer 13

Multiple line vs single Multiple: * Service provided can be differentiated * Labour specialisation possible * Customer has more flexibility * Balking behaviour may be deterred: several medium length queues are less intimidating Single * Guarantees fairness * No customer anxiety regarding choice of queue * Most efficient set up for minimising time in the queue * Jockeying (queue switching) is avoided

Answer 14

If there were no variability, there would be no need for queues to occur Statistically, the usual measure for indicating the spread of a distribution is its standard deviation sigma. However, variation does not only depend on standard deviation. To normalise standard deviation, it is divided by the mean of its distribution. The measure it called the variation of the distribution.

Answer 15

1. External customers arrive to the system * Profit organizations * The shortage cost is primarily related to lost revenues “Bad Will” * Non profit * The shortage cost is related to a societal cost 2. Internal customers arrive to the system * The shortage cost is related to productivity loss and associated profit loss Usually it is easier to estimate the shortage costs in situation 2 than in situation 1.

Answer 16

* Proportionality * contribution of each activity Xj to the value of the objective function Z is proportional to the level of the activity Xj as represented by the CjXj term in the objective function. Similarly, the contribution of each activity to the left-hand side of each functional constraint is proportional to the level of the activity Xj, as represented by the AijXj term in the constraint. * Additivity * Every function in a linear programming model (whether the objective function or the function on the left-hand side of a functional constraint) is the sum of the individual contributions of the respective activities. * Divisibility * Decision variables in a linear programming model are allowed to take any values, including non-integer values, that satisfy the functional and non-negativity constraints. * Since each decision variable represents the level of some activity, it is assumed that the activities can be run at fractional levels. * Certainty * The value assigned to each parameter of a linear programming model is assumed to be a known constant.

Answer 17

**Project planning and control** Stage 1: Understand the project environment * Geo-social environment * Geography and national culture * Econo-political environment * Economy and government * Business environment * Customers, competitors and suppliers * Internal environment * Company strategy, resources and other projects Stage 2: Project definition * Aim, strategy and scope Stage 3: Project planning * Objectives: what is the goal and estimate of cost/ time * Project scope: how to approach, feasibility, major tasks * Contract requirements: reporting and performance, responsibilities * Schedules: activities, tasks, timelines, milestones * Resources: budget and budget control * Personnel * Control: monitoring and evaluating progress and performance * Risk analysis * Identify activities * Estimate the times and resources for activities * Identify relationship and dependencies between activities * Identify time and resource schedule constraints * Fix the schedule for time and resources Stage 4: Technical execution Stage 5: Project control * Earned value analysis * Probabilistic analysis: program evaluation and review technique * Most likely time (m), optimistic time (a), pessimistic time (b) * Mean = a + 4m + b / 6 * Variance = (b – a / 6) ^2 * Use expected times to identify critical path, and compute slack and project time * Total project variance = Sum of variance of critical path activities * Project variance is a measure of the risk involved in the project * Crashing project networks * Process of reducing time spans on activities so that the project is completed in less time. * Focus must be on critical path activities * In order to decide which activity to crash, the ‘crash cost slope’ of each is calculated (crash cost per time period). * Crash the activity on the critical path which has the lowest crash cost slope.

Answer 18

Max-flow min-cut theorem The theorem states that, for any network with a single source and sink, the maximum feasible flow from the source to the sink equals the minimum cut value over all cuts of the network. Equivalently, optimality has been attained whenever there exists a cut in the residual network whose value is zero.

Answer 19

Steady state condition * Enough time has passed for the system state to be independent of the initial state as well as the elapsed time * The probability distribution of the state of the system remains the same over time (is stationary). Transient condition * Prevalent when a queuing system has recently begun operations * The state of the system is greatly affected by the initial state and by the time elapsed since operations startedas

Answer 20

Means purchasing inputs used in the firm’s value chain * Raw material * Supplies * Consumable items * Assets such as machinery, lab equipment, office equipment, buildings Direct purchasing: buying for primary activities Indirect purchasing: providing supplies and services for support activities

Answer 21

Performance based partnership * High dependence on one supplier * Used for strategic products Competitive bidding * In general, no long-term supply contract, rather multiple sourcing * Used for interchangeable products Securing continuity of supply * Securing supply of bottleneck products, if necessary, at additional cost * Reducing dependence on supplier by developing alternative products and looking for alternative suppliers Category management and e-procurement solutions * MRO (maintenance, repair, operating supplies) products require a purchasing strategy which is aimed at reducing administrative and logistic complexity * Electronic catalogues * Article catalogue (standardisation of product assortment)

Answer 22

OR professionals aim to provide a rational basis for decision making by seeking to understand and structure complex situations and to use this understanding to predict system behaviour and improve system performance. Done using analytic and numeric techniques to develop and manipulate models of organisational systems. Types of OR models * Linear programming: objective function and constraints are all linear functions of the decision variables * Network flow programming: special case of linear program where situation can be modelled as a network * Integer programming: variables are required to take integer values * Non-linear * Dynamic programming: process described in terms of states, decisions, transitions and returns. Problem is to find sequence that maximises total return. * Stochastic programming: Uses random variables for some aspects of the problem. Expression can be written for the expected value of the objective.

Answer 23

**Organisation benefits** Increased performance: * Access to innovation * Improved customer satisfaction * Better quality * Improved on time delivery * Increased responsiveness Lower risk: * Less SC disruption * Less reputational damage * Less product scarcity * Fewer delayed responses to crises **Supplier benefits** * Lower operational cost * Motivation to innovate * Increased efficiency * Better planning **Mutual benefits** * Product development time shortening * Quality improvements * Cost reduction * Smooth release of new product * Value co creation

Answer 24

Just in time * When products are delivered when they are needed. Vendor managed inventory * When suppliers take responsibility for a range of contracts to manage the buyer’s inventory. A method introduced to cope with bull-whip effects. Collaborative planning, forecasting and replenishment * When supply chains become integrated. CPFR seeks cooperative mgmt. of inventory through joint visibility and replenishment of products throughout the supply chain.

Answer 25

Categorise existing and potential suppliers as: Strategic Suppliers important for the buying firm in the sense that they provide the buying firm with essential material and capabilities that cannot be substituted Preferred Suppliers that could be replaced, with some effort, in the long-term. Transactional Suppliers that can be easily replaced in the short-term Evaluation criteria: price, delivery, quality, production capability, localisation etc.

Answer 26

Procurement is an auction: * Requirements for the next performance period * Communicate to suppliers (bidders) * Suppliers submit a bid (first price, sealed bids) * The procurement team chooses the winning bidder Procurement, logistics, inventory mgmt. and production control are tightly linked In some markets, 80% of product revenues is directed to suppliers for labour, material and equipment

Answer 27

* Market requires product and service quality at reasonable prices. Depends highly on production and suppliers. * Suppliers are being selected based on their value-added capabilities. * The buying firm has to determine * Product/service attributes * Expected requirements and * Right quality at reasonable price the process: 1. Identify key purchasing 2. Determine puchasing strategy 3. Identify potential sources 4. Limit supplier in pool 5. Determine method of evaluation 6. Make selection

Answer 28

* Process-based evaluation * Evaluation based on suppliers’ production or service processes. * Performance-based evaluation * Evaluation based on (objective) performance measures * Examples: * Categorical * Cost Ratio * Weighted point (linear averaging) * Value based sourcing: * Can the supplier decrease our risk (e.g., reducing bottlenecks/critical parts purchasing; disruption response; exchange rates)? * Can the supplier provide some other competitive advantage (e.g., differentiating factor; new product variant)? * Can the supplier help expand the portfolio to address new customer needs? Categorical method * Categorization of every supplier, in specific areas, based on a pre-defined list of performance variables. * Categorical assessment, e.g. ‘good’, ‘neutral’, ‘unsatisfactory’. * Easy to implement, minimal data required, low-cost * Lacks reliability, subjective, manual process Cost ratio method * Categorization of every supplier by standard cost analysis. * Rating performance at each performance factor. * Specific underperformance areas are identified, objective supplier ranking, long-term improvement potential, comprehensive assessment * Cost-accounting required, complex process, information technology resources required Weighted-point method * Categorization of every supplier by weights on a list of performance variables. * Flexible system, supplier ranking, moderate capital costs, combines qualitative and quantitative factors * Tendency to focus on price, information technology resources required

Answer 29

Objective of the nth iteration: * Find the nth nearest node to the origin Input to the nth iteration: * n-1 nearest nodes to the origin, including their shortest path and distance from the origin. (These nodes, plus the origin, will be called solved nodes) Candidates for the nth nearest node: * Each solved node that is directly connected by a link to one or more unsolved nodes provides one candidate – the unsolved node with the shortest connecting link to this solved node. (Ties provide additional candidates). Calculation of the nth nearest node * For each such solved node and its candidate, add the distance between them and the distance of the shortest path from the origin to this solved node. The candidate with the smallest such total distance is the nth nearest node (ties provide additional solved nodes), and its shortest path is the one generating this distance. Applications * Minimising the distance travelled * Minimising the total cost of a sequence of activities * Minimising the total time of a sequence of activities

Answer 30

OEM: * Vertical integration vs specialisation * Integral products vs modular assembly * Centralised vs dispersed Unpredictable environment Changing technology landscape Increasing dependence on suppliers and subcontractors Implications for future * Value chains are increasingly fragmented and complex * Competition between global supply chains * Managing uncertainty is a key requirement * Emergence of new business models

Answer 31

* R&D risk * Management * Product /process design and technology * Skill set * Procurement risk * Supplier relationship * Raw material * Location * Production risk * Management * Product, process technology * Location * Distribution risk * Management * Product * Location * Sales and marketing risk * Management * Demand projection * Location

Answer 32

Two approaches for supply chain risk evaluation and management **1. Traditional** * Identify supply chain characteristics * Identify risks linked to these * Evaluate risks (impact and probability) * Choose mitigations * Evaluate impact of mitigations * Plan mitigations * Monitor risks and risk mitigation Risk: * Identification * Assessment * Mitigation * Monitoring **2. Configuration approach** Mapping SC: * Network structure * Process flow * Value structure * Product characteristics Event: * Characteristics * Database Identifying risks * Overlaying event data on SC map * Identification of vulnerability led risk Mitigations * Change in network structure * Alternative process flow * Adjusting value structure * Product redesign

Answer 33

Risk mitigation strategies: * Increase capacity * Acquire redundant suppliers * Increase responsiveness * Increase inventory * Increase flexibility * Pool or aggregate demand * Increase capability

Answer 34

Model assumptions: Mean of zero: at any given value of x, the population of the error term values has a mean equal to zero Constant variance assumption: at any value of x the population of the potential error term values has a variance that does not depend on the value of x Normality assumption: At any given value of x, the population of potential error term values has a normal distribution. If this assumption holds, a histogram of residuals should look bell and symmetric Independence assumption:Any one value of the error term is statistically independent of another.

Answer 35

Algorithm to solve the MST problem 1. Select any node arbitrarily, and then connect it to the nearest distinct node 2. Identify the unconnected node that is closest to a connected node, and the connect these two nodes. Repeat this step until all nodes have been connected. 3. Tie breaking: Ties for the nearest distinct node (step 1) or the closest unconnected node (step 2) may be broken arbitrarily, and the algorithm must still yield an optimal solution. However, such ties are a signal that there may be (but need not be) multiple optimal solutions. All such optimal solutions can be identified by pursuing all ways of breaking ties to their conclusion. Applications of the MST problem * Design of telecommunication networks * Design of a lightly used transportation network to minimise the total cost of providing the links * Design of a network of high voltage electrical power transmission lines * Design of a network of wiring on electrical equipment * Design of a network of pipelines to connect a number of locations

Answer 36

An augmenting path is a directed path from the source to the sink in the residual network such that every arc on this path has strictly positive residual capacity. The minimum of these residual capacities is called the residual capacity of the augmenting path because it represents the amount of flow that can feasibly be added to the entire path. 1. Identify an augmenting path by finding some directed path from source to sink in the residual network such that every arc on this path has strictly positive residual capacity. (if no augmenting path exists, the net flows already assigned constitute an optimal flow pattern) 2. Identify the residual capacity c\* of this augmenting path by finding the minimum of the residual capacities of the arcs on this path. Increase the flow in this path by c\*. 3. Decrease by c\* the residual capacity of each arc on this augmenting path. Increase by c\* the residual capacity of each arc in the opposite direction on this augmenting path. Return to step 1. Some applications of the maximum flow problem * Maximise the flow through a company’s distribution network from its factory to its customers * Maximise the flow through a company’s supply network from its vendors to its factories * Maximise the flow of oil through a system of pipelines * Maximise the flow of water through a system of aqueducts * Maximise the flow of vehicles through a transportation network

Answer 37

Machine learning * Supervised learning * Here is the data set where the right answers are given for each example. Please produce more right answers. * Classification * Unsupervised learning * Here is the unlabelled data. Please find peculiarities, similarities or structures (clusters) in the data yourself * Association rule learning * Clustering * Reinforcement learning * Learn to do something by maximising your reward

Answer 38

* Aim: to label data * Create a model that predicts what class label new data should have * Model must first be trained by providing examples * Examples: classify suppliers, predict condition of engineered parts, classify customers purchasing habits Various different algorithms for classification: * Tree induction * Bayesian * Rule based

Answer 39

2. Evaluation: How do we assess how well the network performs? * Initialise with random weights and biases * Show the network a training example * Network calculates the activations of all neurons of all layers (using initial weights and biases) * And then we can compare the value of each output neuron with the value we actually wanted and compute the squared error for each neuron * This is done for all neurons in the output layer and sum up the squared errors * So far this was the error for a single image. So, we do the whole process for ALL thousands of training examples * Then we take the average error for each training example 3. Optimisation: How do we tell the network how it can improve its performance? * We know how to find the minimum * We calculate the derivative, set it to zero * Then we get the point and check if it is a global minimum or not Gradient descent * You start anywhere on the (multi-dimensional) cost function: random initialisation * You “look” into all directions from the point of where you are and determine the direction with the steepest descent: you calculate the negative Gradient (the direction of steepest descent) * You then move one step into that direction * The step size (or “learning rate”) matters * The negative gradient of the cost function tells us how to adjust our weights to take the next step

Answer 40

* Understand model goals * System analysis * Model and simulation specification * Model verification and validation * Design and run experiments * Draw inferences

Answer 41

Economic rationale: * Manufacturing firms in developed countries cannot compete on cost * Installed base argument * for every new car sold there are already 13 in operation, 15 to 1 for civil aircraft and 22 to 1 for trains * Stability of revenues – service vs products Strategic rationale: * Lock in customers * Lock out competitors * Increase the level of differentiation * Customers demand it * Service as a pre-sale activity Environmental rationale: * Environmental rationale

Answer 42

What are the seven principles of service design? 1. Bias toward action 2. Embrace experimentation 3. Radical collaboration: bring together innovators from varied backgrounds 4. Show don’t tell: communicate by creating experiences 5. Focus on human values: understand the people you are designing for and get feedback 6. Craft clarity: produce a coherent vision 7. Be mindful of process: know where you are in the process and what your goals are The phases of service design thinking Empathize * Observe, engage, immerse Define * Define your point of view * Provides focus, reference for evaluating ideas, fuels brainstorming Ideate * Ideate to step beyond the obvious solutions and drive creativity Prototype Test

Answer 43

Findings show that the service journey occurs: * Small, careful and incremental changes * At different organisational levels * The 4th year is crucial. Two concurrent steams of service development: * Continue to build up on current basic and intermediate services * Exploration and piloting of more complex services

Answer 44

Seven critical success factors: **Assess market and internal readiness** **Creating the strategic and cultural context:** * Design service vision * Define customer mindset and engage partners * Develop service culture **Structures and governance** * Define leadership, set organisational structure **Resources** * Define company and individual resources **Engagement and trust** * Engage customer mindset, partners * Enable change **Service processes** * Design and plan service model * Pilot and model * Portfolio mgmt. * Commercial execution **Optimise and communicate best practices**

Answer 45

Supply Network: A set of connected but geographically dispersed firms involved in making and delivery of product/service to end customers

Answer 46

Strategic * investment in plants: numbers, locations * introduction of new products: BOMs used * manufacturing technology * creation of logistics network * make vs buy, supplier selection Tactical * manufacturing system * inventory policy * procurement policy * IT system and information flow * customer strategies, demand planning, forecasting Scheduling of resources (labour, machine, vehicles) Routing of raw materials and finished products Solicitations of bids/quotations, order processing

Answer 47

What technologies are impacting DM today? Sensing: non industrial sensing, network many devices, vision, AR, VR, crowd sourced data Analysis: cloud computing, mobile computer, clustering algos Decision: Machine learning, smart products, optimisation, low cost computing Actuation: Cobots, customers in the loop, AM, FPGAs

Answer 48

Industry 4.0 What is it: framework for enabling the intelligent integration of physical and digital resources, services and humans resources in manufacturing in real time. Rationale: strong individualisation of products, flexible production, hybrid (servitisation) Dimensions: Vertical integration and networked manufacturing systems Horizontal integration through value networks End-to-end digital integration of engineering across the en3re value chain

Answer 49

* The supply chain risk and resilience framework explains the concept of event, vulnerability, risk and resilience. * At its centre is ‘event’ (such as climate change, war, new regulation or financial crisis), which might have significant impact on supply networks. * Next is ‘vulnerability’, which is associated with structure of supply network and particularly its lack of flexibility. * ‘Risk’ appears when key events and vulnerability interacts with each other, which leads to supply network failure. * Next is ‘risk mitigation’, which is an action or set of actions taken by companies to minimise either impact or changes (probability) of risk. * ‘Resilience’ is an ability to recover from network failure, which is achieved by continuously changing supply networks in response to risks by using risk mitigation approaches, such as adopting new processes and /or practices or by reconfiguration

Answer 50

Single vs. multiple sourcing * Assessment with regards to dependence, supply risk and transaction costs Global vs. local sourcing * Local sourcing preferred when product is a high-tech product for which specification often changes; high flexibility and precision required in terms of delivery Partnership or competitive relationship * Competitive relationship mostly used when commodities are purchased, when the products are purchased in in large volumes and when many suppliers are available Buying on contract or buying on spot basis * Contract buying preferred when prices are expected to rise * Advisable to choose a mix between contract and spot buying Price agreement vs. performance agreement * Performance agreement often used when services are purchased (Service level agreement) * Price agreements might be sufficient if standard quality products are purchased (for example certain types of fabric)

Answer 51

Objective of location strategy: to maximise the benefits of location to the firm Location decisions can be determined by: * Marketing strategy * Compete on cost: find low cost location * Compete on level of responsiveness: close to transportation networks/market * Cost of doing business * Growth * Potential access to more customers * Expanding product portfolio * Depletion of resources * Industries where resources determine key success Factors influencing location decisions * Economic * Tariffs, taxes, trade concession, capital subsidies * Temporal * Competition, demand patterns, industry dynamics, presence of related industries (clustering), skilled employees’ engagement * Physical location * Labour cost, developed infrastructure, proximity to market, cost of inputs, competitors locations, specialised inputs * Organisational factors * Strategic role of a factory amongst multiple plants

Answer 52

* M&A * Business growth * Faster lead times/cost reduction * Increase of offshoring Aspects countries should consider: * Country level * Political risks, legislation, economic issues (currency), location, labour, availability of suppliers * Region level * Labour, cost, regulations, proximity to resources, land cost * Site level * Site size/cost, distribution systems, proximity to suppliers, environmental impact, clustering

Answer 53

Irreversible allocation of the firm’s capital – long term/strategic decision Business continuity Impact on supply chain performance * Lead times * Inventory * Responsiveness to demand * Flexibility * Quality

Answer 54

Causes: * Labour * Natural disasters * Machinery * Power grid shutdown * Foreign exchange * Demand: * arises from volatile demand or inaccurate forecasting * Raw material availability and price * Supply: * caused by variability of supplier’s performance e.g. defective deliveries * Process: * results from the unreliability of the production process due to e.g. machine breakdown, employees underperformance, wrong methods used

Answer 55

Supply chain sustainability is the management of environmental, social and economic impacts, and the encouragement of good governance practices. The boundary of responsibility often extends beyond the reach of a corporation’s ownership and control Aim is to achieved traceability and transparency of SC through supplier collaboration Traceability: * Identification of better sources of raw materials, compliance with internal law standards and certification * A tool to build a reputation for supplying high quality products

Answer 56

Inventory types: * Raw materials * WIP * Finished goods Motives for keeping inventory: * Economies of scale * Uncertainty * Speculation * Transport * Smoothing * Logistics * Cost control Attributes of inventory systems: Demand: * Stable or variant * Deterministic or stochastic * Lead time * Review time * Periodic review * Continuous review * Lost sales Cost elements: * Holding cost * Order cost * Penalty cost

Answer 57

Key concepts that make up supply chain risks Events: * Occurrence happening at a determinable time and place, with or without the participation of human agents * Financial shock, trade dispute, geopolitics, natural disaster, disease Vulnerability * Inability to withstand the effects of an event. Uncertainty * Uncertainty related to a known event (risk) and uncertainty related to an unknown event (pure uncertainty) Risk * Chance of event happening that will have negative or positive consequences * Risk is made up of uncertainty, impact, context and nature * Probability of an event x impact of that event Resilience

Answer 58

The Chi square test * Involves comparing the histogram to a discretised pdf of the fitted distribution. * The higher the p value or the lower the test statistic the better the fit. * A disadvantage of this test is arbitrariness in the binning and different bins give different answers * For this reason this statistic should only be used when the distribution being tested is discrete. Kolmogorov-Smirnov * KS statistic is to compare the cdf of the fitted distribution and the cdf of the sample data by taking the max vertical difference between them. * In general, the lower KS the better the fit. * KS \< 0.03 Anderson-Darling * AD statistic weighs the squared distance between the fitted and observed distribution * In general, the lower AD the better the fit. * AD \< 1.5 Criteria information tests can help make decisions * BIC and AIC

Answer 59

Data analytics is… * The extensive use of data, statistical analysis, and predictive models to drive decisions and actions. Analytics has long existed in manufacturing firms: * Total quality mgmt. * Statistical analysis for product quality Increasingly used in all areas of manufacturing… * Which supplier * How should supply chain be configured * Best sales channel * How are products used * What product configurations

Answer 60

Aim * To find interesting associations between data values * Based on the frequency that values appear together * It only finds whether associations exist or not- it does not indicate why there is an association Examples: detecting when manufacturing equipment needs maintenance, detecting what is causing a defect in a product, logistics Metrics: * Support: how pervasive is the rule? * the rule appears in 50% of all the transactions * Confidence: how certain is the rule? * for transactions containing chips (premise), the rule is correct 75% of the time

Answer 61

Aim: * To group data into classes or “clusters” * (so that items in the same cluster have a high similarity to one another but are dissimilar to items in other clusters) * Useful to discover features that distinguish groups * Useful as a pre-processing step for classification: to automatically determine labels * The class labels are discovered by clustering and therefore do not need to be provided * Examples: identify factors that distinguish customer types, identification of products that are returned, determine what machines develop faults Main methods * Partitioning methods (k means) * Hierarchical methods * Density based methods * Grid based methods * Model based methods

Answer 62

The application of digital information [from multiple sources, formats, owners] for the enhancement of manufacturing processes, value chains, products and services Why DM * Cost * Time * Labour * Manage complexity * Better customer service * Quality Why now? * Sensors * Tech (AI, cloud, data analytics) * Globalisation (global supply chain) * Flexible product demand * Product service demand

Answer 63

Making things cheaper, faster, better * Increased productivity * Material & energy sustainability * Resilience to change/disruption mgmt. Making things in different ways: * Distributed production: network of geographically dispersed manufacturing facilities that are coordinated using information technology. * Late customisation * Near customer manufacturing * Specialised Manufacturing in new areas * Production at retailer, the farm, the construction site, home Manufactured product and service blending * Aircraft operational services * Customised logistics * Hospital support services * Appliance repair services * Non production operations with resource constraints, cost thresholds, quality targets etc Summary * more productive, sustainable, resilient, etc * distributed, specialised, customised, localised * Production in a remote / mobile / small scale / one off manner

Answer 64

Supply Chain Risk Mitigations: * Increase capacity * Build centralised capacity for unpredictable demand * Build decentralised capacity for managing supply chain disruptions due to natural disasters * Acquire redundant supplier * Favour more redundant supply for high volume products, less redundancy for low volume product * Centralise redundancy for low volume products in a few flexible suppliers * Increase responsiveness * Favour cost over responsiveness for commodity products * Favour responsiveness over cost for short life products * Increase inventory * Decentralise inventory for predictable, low value products * Centralise inventory for unpredictable, high value products * Increase flexibility * Favour cost over flexibility for predictable, low volume products * Favour flexibility for low volume, unpredictable products * Centralise flexibility in a few locations if it is expensive * Increase capability * Prefer capability over cost for high value, high risk products * Favour cost over capability for low value, commodity products * Centralise high capability in flexible source if possible Unintended consequences of supply chain mitigations * Adding capacity increases cost of operation. High capacity cannot be sustained in the long run if there is perfect competition * Increasing inventory increases cost of operation. * Having redundant suppliers increases cost of operation.

Answer 65

Traditional approach of supply chain risk management: * Identifying Supply chain risk characteristics * Identifying risks linked to supply chain characteristics * Evaluate risks * Choose relevant risk mitigations * Evaluate impact of chosen mitigation * Plan mitigations * Monitor risks and risks mitigation Configuration approach of supply chain * Mapping Supply chain : Including network structure, process flow, value and product characteristics * Understanding event: characteristics and database * Identifying risks: overlaying event data on SC map and identification of vulnerability led risk * Mitigations: Change in network structure, alternative process flow, value adjustment and product redesign

Answer 66

Rational approach Define the challenge – create a specification * To arrive takes time (supplier, client and third party’s) effort, money, patience * Single biggest success/failure factor * Should cover all functionality, is unambiguous, promotes common understanding Identify risks * Manage risk by prototyping, consulting and work on risk areas early * Preparation, build (mechanical, electronic, software) and project (human, interface, supplier) errors * Failure mode and effects analysis Generate alternative solutions, evaluate and select * Postpone the selection, evaluation and gather proposals from a wide variety of sources * Evaluation criteria: technical, practical, timing, commercial, legal, organisational, environmental Plan * Specify, design, procure, build, integrate, test * Break jobs into small tasks, visible milestones, design reviews, iterative development * Actively look for problems, risks that you understand can be managed Implement, commission and test * Integration problems: hardware, software, electrical, interfacing problems (mechanical fit, sensor abilities, robot reach) * Incremental innovation is better * Incremental delivery * Test elements one at a time, step through cycle

Answer 67

A class of industrially hardened devices that provides hardware interface for input sensors and output actuators, PLCs can be programmed to control the outputs based on input conditions and/or algorithms contained in the memory of the PLC consists of: * A CPU (central processing unit ) * Memory for software and data (built in or removable) * Input/output system to allow physical connection to field devices (e.g., switches, sensors, etc.), both digital and analogue

Answer 68

A fixture is a mechanical device that can be used for locating a part repeatedly in a known position and clamping it securely, so that work can be performed on it. Functions of a fixture: * Location * Positioning and orienting a workpiece for an operation * Repeatability * Ease of use * Allow access for operations * Clamping * Holding a workpiece securely during an operation * Adequate clamping force * Reliable clamping force * No part distortion * Workpiece security * Correct clearance Other fixture design criteria: * Poka Yoke * Quick Change: SMED * Flexible

Answer 69

Modular design of production control code: * Reconfigurable production * Manageable module development * Ease of testing and debugging * Customisation capability Issues to consider: * Requirement to link product to customised recipe * Capability of tracking the product through the production process * Track the status of the product as it moves through production * One way is to use RFID

Answer 70

System integrators: * Equipment vendors * Software vendors * Sub system vendors End user: * Operators maintenance * Management team * Facilities

Answer 71

Unit testing: * Throughout production component development * Test functionality * Operational status * **Error conditions** * High level interface System testing: * When modules of production components are ready * Hardware interfaces * Software interface (hand shaking) * **Error/recovery strategies**

Answer 72

**Precision position switch** * A range of high precision measuring and control switches. **Inductive proximity switch** * The inductive proximity switch consists of a coil wound around a ferrite core at the sensing head * High freq. is applied to coil to generate an oscillating magnetic field * When metallic object travels towards field eddy currents are generated reducing oscillation freq. Applications: * Missing washer can be detected * Check metal is right thickness * Check screws have been correctly tightened * Metal components counted as they fall from a bowl feeder * Can detect machine table at its limit **Capacitive proximity switch** * Current sourcing proximity switch * Capacitive switch is mounted below a plastic area above which product passes. Sensor is tuned to detect the presence of the target object. Application: * Sense liquid in plastic tank **Optical proximity switch** An optical proximity switch which senses return light from target surface **Optical through beam sensor:** * Emitter and receiver * Detecting milk in cardboard cartons * Sense label presence **Optical retro-reflective:** * Range of retro reflective sensor can be adjusted, allowing thresh holds to be set. * With no object all light is reflected 100% * With object near the reflector nearly all light is reflected * Check the presence of a label **Optical retro reflective (polarised)** * Shiny metallic objects, cuts out ambient reflected light **Pressure sensor:** Sensing element is silicon diaphragm, integral to the IC chip.

Answer 73

Internet of things is the network of physical devices, vehicles, home appliances, and other items embedded with electronics, software, sensors, actuators and network connectivity which enable these objects to connect and exchange data. What is industrial internet of things? The application of IoT to create value for industrial processes, supply chains, products and services?

Answer 74

* Integrating data from suppliers, logistics, providers, customers * Introducing new technology, peripherals, tools, equipment * Distributed production requiring addition of new data sources, locations, owners * Sensors on board raw materials, parts, products, orders passing through organisation Security, privacy/data IP, benefits are challenges

Answer 75

End effectors: * An end effector is a device at the end of a robot arm that is used to perform some task. (Gripper, Welding head) * The robot is used to orientate and move the end effector into the required position. * Typically, the operation of the end effector is controlled by the robot controller. Typical tasks end effectors perform: * Gripper, Drill, De-burring, Sanding, Nut spinner, Laser welder, Sucker gripper, De-burring * Maintaining part location and accuracy * During the assembly operation it’s critical to consider the total accuracy and repeatability parameters of the production environment. * Accuracy and repeatability

Answer 76

Automated solutions can be considered to be: Dedicated automation: designed to carry out one specific task * High speed operations, solution optimised for specific need * Can’t handle product variations, equipment cannot be re tasked for other activities Flexible automation: designed to carry a variety of tasks * Can handle product variations, make use of standard equipment, payback across multiple product variations, equipment can be re-tasked to other activities * Complexity of solution, operational times can be slower, solution can be expensive

Answer 77

**Anthropomorphic robot** Features: * Typically, six axis configurations * Flexible, can reach points in multiple configuration Applications: * Used for welding, painting, machine loading, assembly, etc **Selective compliance assembly robot arm (SCARA)** Features * Typically, four axis configurations * Two link, cylindrical robot * Flexible, can reach points in multiple configurations Applications * Used for high speed assembly, kitting, packaging, and other material handling applications **Delta robot** Features * Typically four, five or six axis configuration * Parallel robot (multiple actuators working together in parallel) * High speed operation * Constrained work space Applications: * Used for material handling of light weight products for packaging and assembly **Cartesian robot** Features * Typically four, five or six axis configuration * Linear or gantry robot (multiple axis at right angles to each other working in straight lines) * Robot control is simplified due to the use of linear rather than rotary axis Applications * Used for CNC machining, machine loading, packaging and assembly.

Answer 78

CNC * Repeatable * Precise * Good surface finish * High productivity * *Waste material* * *Limited work piece figure* AM * Less material wastage * Geometrical freedom * Material options * Metallurgical bond * *Long cycle time* * *Poor surface finish*

Answer 79

* “the use or introduction of automatic equipment in a manufacturing or other process or facility” *Oxford dictionary* * The creation and application of technology to monitor and control the production and delivery of products and services. *Automatic federation* The replacement of man by machinery: * Physical actions * Data gathering * Decision making Mode of operation where a machine or piece of equipment is capable of working without human intervention.

Answer 80

Benefits: * Improved working environment * Increased production rate * Improved product quality * Reduce scrap and rework costs * Improve factory floor space utilisation * Reduce manual paper-based tracking / scheduling processes Challenges: * Complexity of tasks to be automated out * Production rates to be achieved * Exception handling * Skills required to run production facility * Payback on automated solution * Catering for product change and variation

Answer 81

SCARA PROS * Ideal robot type for inserting screws into holes. Stiff in the Z Axis but compliant in X,Y. * Due to its stiffness in the Z axis it can apply significant loads in the Z axis. This is essential when inserting self-tapping screws. * Best repeatability of the different robot types on the market, making it ideal for the placement of small screws in an electronic assembly. * Some of the fastest robots on the market, allowing it to easily service operations from the two lines and a screw feeder. CONS * Limited working volume, but easy to visualise for a 2D space * Working volume is cylindrical in nature, complex to utilise. * Payloads can be limited if full operating speeds are required.

Answer 82

2. Cartesian PROS * The Cartesian style of robot can carry out fastening type operations. * Cartesian robots are made up from linear axis and can provide large working volumes * Cartesian robots can support significant payloads, suitable for the operation of an electric screwdriver * Cartesian robots have good repeatability, making them suitable for electronic assembly operations CONS * It has limited compliance in the X,Y plane. * Cartesian robots tend to be the slowest of the different robot types. It may not be possible to meet the takt time required in servicing the two phone lines.

Answer 83

3. Anthropomorphic PROS * Very flexible robot, capable of working in a number of planes. (Not required in this application) * Can be re-tasked or have its role extended to other tasks easily. CONS * Stiffness in the Z axis is limited. This is due to limited torque available in the wrist axis. * Complex working volume that is spherical in nature. * The anthropomorphic is one of the slowest robots. * The repeatability of the anthropomorphic robot is mid-range and may need to be examined closely for applications in electronic assembly.

Answer 84

Delta PROS * The Delta robot has good repeatability required for electronic assembly. CONS * The working volume of the work space is limited in the Z Axis. Challenging to accommodate screwdriver operations. * Payloads on the Delta robot is limited and not suitable for screwdriver operations. * The Delta robot doesn’t have the appropriate stiffness in the Z Axis to support fastening type operations.

Answer 85

* A robot can provide a flexible piece of automation hardware * Robots of varying capabilities can be purchased and quickly configured to an application’s needs * Operational tasks can vary depending on production requirements * Operational tasks can be updated as future production requirements are identified * Robots can be easily integrated into factory control systems * Robots can be re-tasked to different automation solutions over time

Answer 86

Definition of a robot “a re-programmable device designed to both manipulate and transport parts, tools or specialised manufacturing implements through variable programmed motions for the performance of specific manufacturing tasks.” Applications: * Arc welding * Cut, grind, debur, polish * Palletising, packaging * Spot welding * Handling * Loading * Handling, deburring * Unloading * Painting * Assembly

Answer 87

Robot performance measures: * Working volume * Payload (max mass a robot can manipulate at a specified speed) * Speed * Resolution (amount of joint motion required to be a recognised change in sensed position) * Accuracy (deviation between commanded and attained position) * Repeatability

Answer 88

Pneumatics: definition Systems operated with air or gaseous medium to impart power or to control power Compressed air pros & cons * Availability: most factories have supply * Elasticity: can be stored in containers * Safety: not a fire hazard * Reliability: components have long working life * Clean technology * Resistance to environment … heat, cold, dirt, corrosion * Economy: low installation and maintenance cost * Choice of movement: linear, angular, rotary, gripping * Expensive!!

Answer 89

Valves * Directional control valves start, stop or change the direction of flow in compressed air applications * Operator is mechanism that causes valve to change state * Manual, mechanical and electrical * Monostable * Spring return, defined preferred position, automatic return, latched signals * Bistable * No return position, remains in either position, pulse signals Actuators * Part of the system that converts potential energy from compressed air into mechanical motion * Can be linear or rotary * Single (spring and open to atmosphere) or Double acting Other equipment: * Air filter: removes contaminants * Air regulator: controls and stabilises air pressure downstream * Air lubricator: to aid life of components * Precision regulator: controls and stabilises pressure downstream, but to a much higher tolerance

Answer 90

Document specifying * the functionality of an automation project * and agreeing the participation of different parties involved (**End-Users and Systems Integrators**). Technical document that: * Defines **the functional scope** of the project. * **P****rovides common understanding** between parties. * Should be **unambiguous and testable.** * Forms the basis of contractual agreements * Referred to as the bible of the project by * helping to **eliminate specification creep** * and **project disagreements.** Types of information found in a functional specification: * **Functionality** * **Error handling** procedures * **R****ecovery processes** * **Processes requiring manual intervention** (Operation Assistance) * **Production rate** * **Required uptime** * **Number of operators** * Frequency of incoming and outgoing components * **Delivery format** of incoming / outgoing components * **Quality** of **components** * **Services** required **to run** the solution (e.g. 120 PSI compressed Air, 240VAC 10Amps) * **Maintenance schedule**

Answer 91

* Solution testing is an important activity * Full functionality should be tested. * Tests should be performed early * To provide time to remedy any issues that arise Automation solutions made by * integrating multiple units of automation together to provide an integrated solution (system). * Testing process broken into two phases: * unit testing * system testing. * As individual modules are tested and integrated with each other, system tests can be carried out. * System tests evolve as the scale of the system is increased. * **S****equence**of integrating modules together and undertaking system tests**is critical.** * Functional specification used to develop a plan for unit and system testing. Unit tests should include: * **Unit Functionality / Performance** * Operational Status (process requiring human intervention) * **Error Conditions** * **Interfaces** of both Hardware / Software System tests should include: * **Integrated Functionality / Performance** * **Error Handling / Recovery Strategies** * **Interfaces of both Hardware / Software**

Answer 92

Project milestones that should be considered in the development, integration and delivery of a typical automation project: 1 - Idea (Initial Requirement) [End Customer] 2 - Talk to various system providers [End Customer] 3 - Provide a Requirement Specification for Tender [End Customer] 4 - Basic Tests, Submit Functional Specification [Systems Integrator] 5 - Agreed Functional Specification (Performance Requirements) [All Parties] 6 - Prototype key technology components [Systems Integrator] 7 - Design System [Systems Integrator] 8 - Procure Components [Sub Vendors] 9 - Build Production System [Systems Integrator] 10 - Integrate System Components [Systems Integrator] 11 - Factory Acceptance Test (FAT) [All Parties] 12 - Site Acceptance Test (SAT) [All Parties] 13 - Final Performance Test [All Parties]

Answer 93

The purpose of a functional specification is to: * **Specify what the automation will achieve.** * It will form the basis of the **contract** between the automation vendor and the customer, and will form the basis for the acceptance trials. * It will minimise **specification creep.** * Provide a base from which requested changes during the project can be **identified and appropriately costed.** * It forms the main means of communication between the customer and the vendor to minimise the chances of disappointment and / or nasty surprises

Answer 94

The main areas to be included in the functional specification: * What the system has to deliver (not on how this should be achieved). * **Form**, **quality** and **method of delivery** of incoming materials. * Form and method of delivery of **finished products**. The functional specification will require further iteration with **material suppliers** and **customers**. The following additional areas should be covered: * The context within which the automation will operate, e.g. **skill levels of operators**, **reliability of interfacing equipment** outside the control of the vendor. * **Cycle Time**. * Some measure of **availability**, usually expressed as output over a specified period. * **Form and extent of manual intervention**. * Scheduled periods of operation and maintenance. * **Levels of defects**, and what to do when defects are detected. * **Error detection and recovery**, recoverable and non-recoverable errors. Form of error logging. All the statements in the functional spec should be testable and so vague wording should be avoided. For example, “The system should operate reliably” is not acceptable, some measures of reliability should be provided.

Answer 95

Unit Tests * Unit tests are carried out on each component (Unit) of a production system. * Typical components of a production system would be for example a Robot, Part Feeder or Conveyor Docking Station. * Each component would be tested in isolation to ensure it works correctly and meets performance requirements specified within the functional specification. Typical Unit tests would include: * Test that **hardware functionality** meets **performance specifications** * Operational **status** of **hardware** is reflected within the **unit control system**. * **Error conditions** are detected and captured correctly. * Unit control systems **interfaces** work correctly allowing systems integration to take place. System tests * System tests are carried out on groups of production components once individual unit tests have been completed. * A number of components are integrated together in these tests. * The number of components is gradually increased as success criteria are meet. * Typically these tests examine the way production components work with each other both at a hardware and systems level. Typical System tests would include: * Test **hardware interfaces** between production components. * Ensure **correct software hand-shaking** between component **control system** and overall production system. * Ensure that **error recovery strategies** for recoverable and non-recoverable errors work correctly. These tests will go onto include specific production scenarios and provide the ground work for the **Factory Acceptance Tests (FAT) and Site Acceptance Tests (SAT)**

Answer 96

Issues with batch production in pharma * Batch is very versatile but extremely slow and not very precise. * There is approximately a 2- year timeframe from the start to the end of the process development (primary manufacturing part only). * This approach requires capital intensive investment very early in product development to allow the running of clinical studies. * This same process needs to be able to ramp up to full production. * Therefore very high cost associated with failure. * The batch approach is also not very agile to deploy around the world and leads to centralised manufacturing, whereas local production and distributed manufacturing may be important for future cost reduction. * In batch manufacturing, it is difficult to reconfigure or change the design and this again adds to the cost of the products. From lectures * A large % of products in different phases fail, but clinic must be supplied for years and plan for success * If launched, typically market is supplied for 10 years * Demand volume is uncertain * Once patent has expired, product volumes are likely to fall * Orders must always be fulfilled * Must manufacture to strict codes It’s hard to plan * If product fails, equipment can be reused * But it is labour intensive and slow in making the product

Answer 97

Try to be agile instead: * Repurposed or negligible cost or time to change * Precise * Fast to supply * Low labour 3 ideas: * **Modularisation** * System is deconstructed into more independent units (modules) * Useful for reducing the complexity of the system * Leads to * **Replication, mobility, standardisation** means * **Increased speed in delivery and lower cost** * Digitalisation * Leads to: * Faster connected, reduction of downtime due to automation * Data for predictive modelling * Maintenance, how to do a task, deep learning, automating design * Process intensificationusing continuous manufacture * **Footprint is smaller** for same output * Leads to **small precise** plant * Continuous processing is a technology that provides, **small precise replicatable** production. One approach * Substituting a number of the batch steps with a continuous process. * The approach requires the design of a modular continuous manufacturing plant. * This building-block approach allows * **reconfiguration**, **agility** to deploy, agility to re-usein other processes if the product fails, * benefit of the **precision** and higher levels of **automation** achieved in **continuous** **manufacturing** and * the ability to **build closer** to the point of **distribution** rather than have large centralised manufacturing sites. * Each module is a unit operation and **savings** will be realised even by replacing a sequence of a few of the batch steps. It may be noted that pharmaceutical companies are risk averse about moving the entire process to continuous manufacturing because of the challenge of controlling crystallisation and the significant knowledge currently in place that surrounds batch processing in this field.

Answer 98

* Oil and gas provides more than 75% of UK’s total primary energy * By 2035 will still be 66% * Electricity, transportation and heating account for roughly one third of the UK’s primary energy demand, with oil for transport and gas for heating dominating these markets. * Natural gas is the cleanest of all fossil fuels, burning nearly twice as efficiency as coal and producing much less CO2 per unit of energy

Answer 99

Different production fluids * **Crude oil** is a mixture of 200 or more organic compounds, mostly hydrocarbons. Graded according to API number (higher API = lighter, thinner crude) * **Natural gas** as used by consumers is almost entirely methane. Wellhead gas requires significant additional processing to meet transportation pipeline specifications. * **Condensates or natural gas liquids** associated with natural gas are a valuable by product. They are widely used as raw materials for oil refineries and petrochemical plants.

Answer 100

Production facilities can vary from onshore wells to offshore floating wells. Process from production wellheads to export: * Production well head * Production separators: * Separate water, crude oil and natural gas * Gas * Compressed * Gas meter * Pig launcher * Gas pipeline * Oil * Storage * Crude pump * Oil meter * Pig launcher * Oil pipeline

Answer 101

Production well head * Assembly of valves, spools, pressure gauges and chokes to control production * Sits on top of the oil/gas well, leading down to the reservoir * Dry completions are either onshore or on the deck of an offshore structure * Wet completions are subsea, below the surface

Answer 102

Production separators: * Most wells give a combination of gas, oil and water that must be separated * Gravity separation: well flow is fed into a horizontal vessel * Residence time is typically 5 minutes, allowing the gas to bubble out, water to settle at bottom and oil to be taken out in the middle * Pressure is often reduced in several stages (high pressure separator, low pressure separator etc.) * Horizontal separators: * large liquid handling capacity * Sufficient time for settle out of liquid droplets from the gas * Vertical separators (scrubbers) * High gas volumes * Small footprint area

Answer 103

Compression * Gas from separators has lost so much pressure that it must be recompressed to be transported * Turbine compressors gain energy by using a small proportion of natural gas that they compress * Turbine operates a centrifugal compressor, which contains a type of fan that compresses and pumps the natural gas * Compression system includes a large “train” of associated equipment such as scrubbers (removing liquid droplets) and heat exchanges, lube oil treatment etc.

Answer 104

Oil: processed onshore rather than offshore as it is easier. Oil terminals are intermediate oil gathering and distribution stations between offshore oil production locations and onshore oil processing facilities (refineries). Basic functions: * Reception of crude oil * Stabilisation of crude oil (dehydration/desalting, gas/water treatment) * Fractionation of associated gas into propane and butane * Storage of stabilised crude, LPG * Export/ shipment of products into tankers for distribution to refineries Gas terminals: * Function of the terminal is to process the raw gas to provide sales quality gas and liquid hydrocarbon by products. * Gas arrives onshore at around 3 degrees. * Internal cleaning and inspection of the pipeline is done with pigs (dirt/debris/wax/scale removed) * Inlet gas receiver catches slugs of liquid from the pipeline

Answer 105

Process from production wellheads to export: Production well head * Assembly of valves, spools, pressure gauges and chokes to control production * Sits on top of the oil/gas well, leading down to the reservoir * Dry completions are either onshore or on the deck of an offshore structure * Wet completions are subsea, below the surface Production separators: * Most wells give a combination of gas, oil and water that must be separated * Gravity separation: well flow is fed into a horizontal vessel * Residence time is typically 5 minutes, allowing the gas to bubble out, water to settle at bottom and oil to be taken out in the middle * Pressure is often reduced in several stages (high pressure separator, low pressure separator etc.) * Horizontal separators: * large liquid handling capacity * Sufficient time for settle out of liquid droplets from the gas * Vertical separators (scrubbers) * High gas volumes * Small footprint area Gas Compression * Gas from separators has lost so much pressure that it must be recompressed to be transported * Turbine compressors gain energy by using a small proportion of natural gas that they compress * Turbine operates a centrifugal compressor, which contains a type of fan that compresses and pumps the natural gas * Compression system includes a large “train” of associated equipment such as scrubbers (removing liquid droplets) and heat exchanges, lube oil treatment etc. Heat exchanger needed after to remove heat * Shell and tube heat exchangers * Consists of a bundle of tubes enclosed in a cylindrical shell. The ends of the tubes are fitted into tube sheets, which separate the shell side and tube side fluids. Baffles provided to direct the fluid flow and support tubes. * Can be heavy and space consuming * Suitable for high pressure operation * Robust designs with long operational history * Plate heat exchangers * Series of corrugated, pressed metal plates clamped together * Offshore the use of plate heat exchanges has become universal due to compact size and low weight. * Oil cooling prior to storage or pipeline export and some low-pressure gas duties. * Printed circuit heat exchangers * Constructed from flat metal plates with chemically milled fluid flow channels. * High heat transfer surface densities * Suitable for high pressure applications and wide temp range * Compact design leading to substantial weight and space savings * Low maintenance due to corrosion resistant materials and all welded construction Gas meter Pig launcher Gas pipeline Oil: processed onshore rather than offshore. Onshore processing plants called terminals. Storage Crude pump Oil meter Pig launcher Oil pipeline

Answer 106

How to make a superconducting magnet Wind coils * 20-50 km wire per magnet * Wire costs approx. $1/m * Coil diameters between 1.5-2m * Coil weights 20-980 kg Pot coils in epoxy resin Assemble coils Check homogeneity at RT Joint magnet (joints must have resistance \<10^-11 ohms@ 4K) * Pair up leads to cancel forces * Dissolve copper matrix with conc. Acid Fit magnet to cryostat (heat transfer to be \<1W) Pressure test cryostat Chill magnet to 4K using 3,000-5,000 litres of liquid He Run magnet to field (460-700A DC @10V) Test magnet and cryostat Ship magnet (if shipped cold ‘time to dry’ is 20-28 days)

Answer 107

Puttick grid The way a product is manufactured should be governed by: * Production volume and market uncertainty * Intrinsic product complexity (including variety) These aspects drive all relevant parameters: * Product **design** & **material** choice * Production **methods**, **tooling** and **equipment** choice * Degree of **automation** * Degree of **integration** * **Location**, **logistics** and **distribution** * **Assembly configuration** choices * People and organisation * Production control systems

Answer 108

* Product volume and variety * Expected product life span * Market uncertainty * Process novelty * Component/task variability * Precision, cleanliness, quality, regulatory etc. * Component complexity

Answer 109

What are the different assembly system configurations? * Manual: people do the job * Mechanised: machines help people do the job * Hard automated: machines do job (same every time) * Turntable * Indexing: where different elements of production are at different rotation locations * Constant velocity: bottle production * Track * Pallet based. Asynchronous * Indexing/synchronous: cars production * Flexibly automated: robots and other software driven machines do job (can be different) * Based on off the shelf robots: SCARA, anthropomorphic, cartesian, delta etc. * Custom multiaxis

Answer 110

What are the examples of the necessary supporting processes and infrastructures? * Packaging and feeding * Order retained: bandoliers, tubes * Order re-gained: bowl feeders, centrifugal feeds * Sensory systems: proximity imaging, gauging * Actuators: pneumatic, hydraulic, servo electric, solenoid * Conveyors, turntables, x-y tables * Proprietary operating systems and programming languages * Message: exploit what’s out there and don’t reinvent the wheel

Answer 111

Leading process for manufacturing of plastic products: high volume, identical product Cost: * High tooling cost depending on complexity and number of cavities * Low unit cost Typical application * Automotive * Consumer electronics * Appliances * Industrial products * Household products Suitability: * High volume mass production Quality * Very high surface finish * High repeatable process Related processes * Reaction injection moulding * Thermoforming * Vacuum casting Speed * Cycles between 30 and 60 secs

Answer 112

How does an injection moulding machine look and work? * Clamping * Injection * Cooling * Ejection * Plastic granules loaded into hopper * The screw within a heated barrel forcing the polymer towards the nozzle. * The clamping of the mould cavity and the mould. * The injection of the molten polymer (details about runners and shot) * The cooling of the mould * The ejection of the component (ejection pins) * The final removal of the sprue * Recycling of waste back into the process

Answer 113

What are the important specs for injection moulding? * Clamping force * Keep as low as possible: reduce wear and tear without generating flash * Injection pressure * Mould internal pressure curve * First speed of filling must be adequate * Switch over to holding pressure * No residual pressure when mould is opened * Shot size: volume of the part plus runners and gates * Closing force: needed to hold mould for packing and cooling * Number of cavities x projected parting line part surface x mould cavity pressure

Answer 114

What are the other techniques for injection moulding? Gas assisted injection moulding * Shut off valve closes to prevent plastic material seeping back into injection head. Gas is injected into the core of the plastic, which is still molten. The gas progresses the molten plastic into the extremities of the cavity Multi shot Blow moulding

Answer 115

Advanced applications of polymers: Self-healing Drug delivery * Release from surface * Diffuse from swollen network * Release due to erosion * Efficiency depends on chemical structure and porosity of particle Organic solar cells LEDs * Holes injected into conductive layer, electrons injected in emissive layer, recombine at interface emitting light

Answer 116

Heat exchanger needed after to remove heatShell and tube heat exchangers * Consists of a bundle of tubes enclosed in a cylindrical shell. The ends of the tubes are fitted into tube sheets, which separate the shell side and tube side fluids. Baffles provided to direct the fluid flow and support tubes. * Can be heavy and space consuming * Suitable for high pressure operation * Robust designs with long operational history Plate heat exchangers * Series of corrugated, pressed metal plates clamped together * Offshore the use of plate heat exchanges has become universal due to compact size and low weight. * Oil cooling prior to storage or pipeline export and some low-pressure gas duties. Printed circuit heat exchangers * Constructed from flat metal plates with chemically milled fluid flow channels. * High heat transfer surface densities * Suitable for high pressure applications and wide temp range * Compact design leading to substantial weight and space savings * Low maintenance due to corrosion resistant materials and all welded construction Air cooled heat exchangers * Where cooling water is too costly. * Multiple calculations are required to produce an optimum design considering air flow rate, tube design, fin types etc.

Answer 117

What properties depend on molecular weight? * Modulus * Strength * Viscosity * Melting temperature * Glass transition temperature

Answer 118

Gel permeation chromatography * Type of size exclusion chromatography * Measures molecular weight distribution and structure * Separates based on the hydrodynamic volume of the polymer * Higher MW, higher hydrodynamic volume * Pores exclude large molecules, so they move faster through the column Factors affecting GPC spectrum: * Sample interaction with column * Temperature * Flow rate * Gel permeation chromatography is a separation technique. * The columns contained insoluble beads with a rigid pore structure. * The pores can exclude very large molecules, allow partial permeation of medium sized polymers and allow total permeation of smaller molecules. * The larger molecules therefore don’t have a long residence time in the column and flow through. * This means the polymers are separated with the largest coming out first and smallest last. * The full molecular weight distribution can be defined and compared with previous results to see if this is influencing the mechanical behaviour.

Answer 119

Differential scanning calorimetry * Thermal energy of a sample is monitored as a function of temperature * Measures thermal energy of phase transitions (crystallisation, melting point, Tg) * Heat capacity increases above Tg * Heat released on crystallisation and absorbed on melting * The amount of energy needed to increase the temperature of a sample is measured. * This detects phase transitions because of the quantity of energy needed to change temperature. * The glass transition temperature can also be observed. * Also, the percentage crystallinity can be defined.

Answer 120

Thermogravimetric analysis * Measure thermal stability of a sample * Mass of a sample is measured as a function of temperature * Can identify material composition and presence of contaminants * Characteristics different in inert or oxidising environment * Derivative curve highlights different mass loss events * Percentage weight loss can be used to calculate composition * This thermal technique measures the rate of change in mass as a function of temperature. * This can identify changes in the oxidative stability and the composition. * This is a highly sensitive technique and any contamination would be immediately highlighted. * This technique is often used to identify the percentage of filler in a polymer sample, which also effects the mechanical properties.

Answer 121

UV spectroscopy * Can identify material composition and presence of contaminants * Measures absorbance of UV by the sample * Can be used to identify chromophores * Absorbance proportional to concentration

Answer 122

Fourier transform infrared spectroscopy * Can identify material composition and presence of contaminants * Measures vibration and stretching of chemical bonds * Used to examine structure and presence of functional groups * Samples can be solid, liquid or gas

Answer 123

Quench: * wire stops superconducting, becomes resistive and 1000 litres of liquid He suddenly boil away Electrical short Homogeneity * Lack of either intrinsic or induced by site factors Decay * Full field not maintained between service intervals – maximum loss allowed is 0.1ppm/hr Boil off problems * Cryostat performance poor – system will require frequent topping up of liquid helium * Poor vacuum (leak) * Thermal short * Poor connection to refrigeration

Answer 124

What are the safety hazards: * Strong magnetic fields * Extreme cold * Large heavy magnets * Strong acids – HF and HNO3 What are the new trends: * Minimum He system/ ‘dry’ system * Higher fields * Warm superconductors * Cheaper systems: suitable for unsophisticated/low tech environments

Answer 125

LCA * Standardised framework for determining the environmental impact of product or process, to allow comparisons to be made * But interpretation varies and users can select different options * Should cover entire life cycle of product, but many studies don’t do this Difficulties with biopolymers: What should be included within agriculture: * Soil carbon/nitrogen dynamics * Nitrogen emissions from composting * Manufacturing environment, maintenance of equipment Location specific: * Transport requirements * Incineration efficiencies * Farming practices * Energy production is country specific * Electricity has different impacts depending on how it is generated Disposal often ignored Studies look at limited impact factors Impact categories include: * Contribution to climate change * Resource depletion * Ozone depletion * Energy and water use * Acidification * Eutrophication: increased nutrients in water systems resulting in excessive bland growth * Toxicity Can’t be combined: impacts are assessed separately

Answer 126

What is a laser? * Laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation * Laser means: light amplification by stimulated emission of radiation Stimulated photos have same: Direction, polarisation, phase, wavelength Laser resonator formed with mirrors either side of gain medium

Answer 127

Different laser media: * Gas: electrical discharge * Solid state: optical excitation * Semiconductor: electrical current * Dye: optical excitation Common properties: * Directionality * Brightness * Monochromatic (narrow band of wavelengths) * Spatial coherence (better focusability)

Answer 128

What are the different solid state laser geometries? Rod Slab Thin disk Cladding pumped fibres What does a fibre look like?

Answer 129

What are the different applications for fibre lasers? Material processing * Welding * Accurate and consistent processing: fast, flexible and high strength * Low levels of thermal distortion * Able to weld difficult applications * 3d printing * High levels of beam stability: stable and well controlled * Process a variety of powders * Ideal for AM: Inherent back reflection protection * Cutting * Highly productive: match leading cutting speeds * High accuracy and repeatability: intelligent software and stability * Large range of materials and thicknesses * Energy efficient * Ablation and cleaning * No solvents/chemicals * High quality, minimal heating, non contact * Drilling * Small feature size, high aspect ratios, various materials * Micromachining * Marking/engraving * Permanent * Non-contact: no wear * Versatile application * High speed, high precision Sensing * Vibration measurement * Oil and gas exploration * Remote gas sensing * Terrestrial mapping * Wind sensing Healthcare * Vision correction * Kidney stone ablation * Skin rejuvenation * Soft tissue ablation * Dentistry Other * Cinema projection * Communications * Directed energy weapons Applications: * Automotive: cutting, marking, welding * Batteries: welding, drilling, engraving, marking * Medical: welding, cutting * Advanced manufacturing: micromachining * Solar: cutting, marking, welding * Aerospace: drilling, welding, cutting, marking * Dental: engraving and marking

Answer 130

Diamond turning * Zero or slightly positive rake angle for soft materials * Negative for IR materials * Highest cutting speed that can be permitting whilst providing good dynamic stability * Vacuum extraction of swarf to prevent scratching * Flood oil or spray mist coolant on metals * Hard brittle materials control the feed rate * Depth of cut is less sensitive for hard materials IR optics: * Saw * Rough grind * Diamond turning * Clean * Coating UV optics: * Saw * Lap * Rough grind * Fine grind * Clean * Ion beam figuring * Cleaning * Coating

Answer 131

Factors influencing workpiece accuracy and production capability Environment related * Temp variation * Vibrations * Seismic * Through pipes * Air borne (noise) * Electric noise Workpiece related * Stiffness variation * Thermal distortion * Clamping distortion * Residual stresses * Heat response Process related * Tool geometry * Tool wear * Tool mounting (dynamic stiffness) * Process variations with tool wear * Specific energy variations * Cutting force variations * Removal mode * Coolant variations Machine tool related * Motional accuracy * Deflection (stiffness) * Thermal distortion * Dynamic resonance’s * Accuracy/ resolution of measuring systems

Answer 132

Chip manufacturing process * Silicon ingot sliced into blank wafers * 20 to 30 processing steps later it is a * Patterned wafer * This is diced into individual dies * This is tested and bonded to package * This packaged die is then tested and shipped to customers

Answer 133

Patterning process * Prepare wafer * Apply a photoresist * Align a photomask (Cr and glass) * Expose to UV light * Develop and remove photoresist exposed to UV light * Etch the exposed oxide * Remove remaining photoresist

Answer 134

What are the three technologies that determine the performance of semiconductor lithography systems 1. Resolution capability of the projection lens: for forming extremely intricate electronic circuit patterns * Consists of more than 20 lenses, some over 1m long 2. Alignment accuracy: ensuring that the next pattern is accurately aligned to the base pattern * When electronic circuit patterns are repeatedly formed on a silicon wafer many times, they must be positioned with accuracy to the nanometre 3. Throughput: indicates the processing efficiency of a semiconductor lithography system * Productivity during IC mass production is improved when high speed movements of the wafer stage and other processes increase throughput

Answer 135

Why is feature size important? What is the limitation to feature size? * Progress in semiconductor manufacturing is all about reducing the size of the features that make up integrated circuit (IC) designs. * Smaller features allow for faster and more advanced ICs that consume less power and can be produced at lower cost. * Resolution limited by wavelength, currently extreme ultra violet is used

Answer 136

What are the other options for silicon chips? Quartz mask in contact with silicon Mask pressed into molten layer of silico

Answer 137

How does roll to roll printing work? * Raw materials * Deposition * Patterning * Packaging * Finished product Examples include: * OLED lighting * Solar cells * Flexible display * Flexible battery * Flexible RFID

Answer 138

What are the automation challenges of roll to roll printing? * Register control: position match * Tension control * Synchronisation * Positioning * Cam calculation * Winder * Cross communication * Motion control * Virtual master

Answer 139

Nanoscribe: * Laser beam sent through an inverted micro scope onto a piezoelectric 3D scanning stage * Laser beam fired through lens to hardens material (light photoresist). * Material hardens through polymerisation * This process employs two photon photolytic techniques and high resolution positioning. * The laser beam itself has a computer-controlled beam guidance system that translates a 3D CAD model directly into 3D structures of almost any complexity at any scale. * Essentially it can fabricate microstructures as small as 500 nm, including those with complex geometries and support structures, at extremely high resolutions (100nm with reports of new materials reaching 45nm). * The 3D printing technology that Nanoscribe developed has allowed sub-micron parts to be fabricated with geometries and internal structures that would be completely impossible to create using standard micro-scale manufacturing techniques.

Answer 140

Fountain pen nanolithography * Deposit a nanoparticle dispersion of material * FPN is a printing method, which, utilises a reservoir filled with nanoparticulate ink. * These ink solutions can undergo nanochemical changes during the lithography process, resulting in the desired functional lines and structures. * Line width control from 15 nm to over 1000 nm have been demonstrated. * Line produced showed micrometer lengths, consistency of line dimensions, precise placement, and conductivity. * Similar to the reservoir in fountain pens, the nanopipette reservoir enables numerous lines to be printed without refilling. * This technology could be expanded to the production of conductors and actuators, correction of flat panel displays, and mask repair applications.

Answer 141

Ion beam machining * Ion source fired through imaging gas * This is then focused through apertures and scanning deflectors * Before being fired through the final lens at the workpiece * Size of feature determined by size of ion: * Gallium (largest) * Neon * Helium (smallest, 0.5nm)

Answer 142

Manufacture of core such as honeycomb Tends to be batch production * Labour intensive * Aluminium: print wheel adds adhesive to aluminium foil * Strips are cut and stuck together * Heated under pressure * Cut and expanded * Nomex: print wheel similar * Cut and stuck together * Heated under pressure * Expanded and heat set * Dip in phenolic resin and cured at 150 degrees

Answer 143

How is carbon fibre manufactured? * Bulk chemical: AN * Batch is then polymerised: PAN * Dope (high energy required in solvent recovery process) * Fibres are then spun * Fibres are washed and stretched: PAN precursor fibre * Oxidise and carbonise: slow process * Surface treatment and sizing

Answer 144

How is prepreg manufactured? Solvent impregnation process: * Carbon fibres sheets rolled out. * Accumulator at either ends to tension the fibre and to allow the process to run continuously between rolls. * Sheets go through solvent to add resin * Sheets travel up column and undergo solvent management * Inspection Light - to test if light can go through (pass or fail test) * Compaction rollers * Total weight inspection * Protective poly at the end to separate fibres. Prepreg impregnation process: * Resin is pressed onto paper using a film weight check * In separate process carbon fibres are rolled out * As this happens paper covered in resin is pressed each side of the fibres * It is heated in a heat table * It is then cooled and paper is removed leaving the resin on the fibres * Light table used to measure consistency of fibres * Then protective poly is rolled on High volume, low cost process Residual solvent is a problem Negative environmental impact

Answer 145

Manufacturing with prepreg * Hand Lay Up - High waste, low investment, high labour * Automated Tape Lay Up - Medium waste, moderate investment, lower labour * Automated Fibre Placement - low waste, high investment, little labour

Answer 146

What are the alternative methods for manufacturing composites? * Compression moulding: fibres are chopped and compressed with compacting rollers and resin * Infusion: fibres are laid in part and resin is injected under a vacuum throughout the part * Thermoplastic prepreg

Answer 147

What are the new trends in fibre growth? Wider: * Bigger, stiffer roller sets, more powerful motors * Demand for single product to avoid cost of changes * No defects in production or delays = QUALITY Faster: * Same time in process therefore longer equipment * New chemistry: faster reactions therefore shorter process time Heavier * Thicker filaments currently have poorer properties as they are less uniform * More filaments per tow: properties affected by oxygen diffusion into bundle

Answer 148

What factors are considered when selecting an adhesive? Substrates to bond Cure speed, pot life, gap filling, colour Chemical resistance, temperature resistance Specific approvals

Answer 149

What are the different joint loading conditions? * Tension * Compression * Shear * Cleavage * Peel

Answer 150

Give examples of potential defects that can occur in injection moulded parts * Short shot * Humidity * Drying used pre process * Contamination by other coloured granules * Sink marks or Voids: * Depressions on one side of a component due to the thicker section or a large feature on the other side. These thicker areas shrink upon cooling to give the depression. The cooling time needs to be sufficient to allow cooling in the mould. * Knit lines and Weld lines: * This appears as a discoloured line, where molten plastics meet as they flow from different parts of the mould. The flow fronts do not bond correctly, most often due to partial solidification. * Warping * A deformation or bending where there is uneven shrinkage across the component. This is usually due to uneven cooling across the material. Different cooling rates or rapid cooling leads to internal stresses. * Flash * If the clamp force is not sufficient, the mould/die are not precisely manufactured, the mould/die are worn or corroded or if the injection pressure is too high, there will be a leak of the polymer around the join leading to flashing. Which of these issues can CAD solve? CAD based analysis: * Warp analysis: used to predict shrinkage as a result of stress on the mould * Cooling analysis: checks for uniform cooling throughout the mould. Potentially reducing cooling time

Answer 151

What are the different AM methods? * **VAT photo polymerisation (StereoLithogrAphy):** material is cured by light activated polymerisation * Continuous liquid interphase production: continuous elevation, liquid resign, o2 permeable window * Advantages: good resolution, surface finish and rapid * Disadvantages: limited materials, messy, support removal * **Material jetting:** droplets of build material are jetted to form an object * UV lamp and inkjet heads and levelling roller * **Binder jetting:** liquid bonding agent is jetted to join powder materials * **Material extrusion (Fused Filament Fabrication):** material is selectively dispensed through a nozzle and solidifies * Advantages: widest range of materials, widest range of processing conditions, multi material, dedicated support material * Disadvantages: surface finish, toolpath planning, slow rate * **Sheet lamination (LOM):** sheets are bonded to form an object * **Powder bed fusion (Selective Laser Sintering/SLM):** energy (typically a laser or electron beam) is used to selectively fuse regions of a powder bed * Mount platform, heat bed, perform cycle, cool, remove platform, post process (CNC, surface finish, anneal etc) * Advantages: can print metals, rapid, good surface finish, wide variety of materials * Disadvantages: powder handling, high energy, post processing * **Directed energy deposition (LENS):** focused thermal energy is used to fuse materials by melting as deposition occurs * Powder fired into a laser beam

Answer 152

Why is AM increasingly widespread now? * Rapid prototyping * Reducing assembly * Complex geometries * Multi material * Enhanced performance * Low volume manufacturing * Supply chain efficiency (low inventory) * Reduced material consumption

Answer 153

VAT photo polymerisation (StereoLithogrAphy):material is cured by light activated polymerisation * Continuous liquid interphase production: continuous elevation, liquid resign, o2 permeable window * Advantages: good resolution, surface finish and rapid * Disadvantages: limited materials, messy, support removal

Answer 154

**Material extrusion (Fused Filament Fabrication):** material is selectively dispensed through a nozzle and solidifies * Advantages: widest range of materials, widest range of processing conditions, multi material, dedicated support material * Disadvantages: surface finish, toolpath planning, slow rate

Answer 155

**Powder bed fusion (Selective Laser Sintering/SLM):** energy (typically a laser or electron beam) is used to selectively fuse regions of a powder bed * Mount platform, heat bed, perform cycle, cool, remove platform, post process (CNC, surface finish, anneal etc) * Advantages: can print metals, rapid, good surface finish, wide variety of materials * Disadvantages: powder handling, high energy, post processing

Answer 156

* Material jetting: droplets of build material are jetted to form an object * UV lamp and inkjet heads and levelling roller * Sheet lamination (LOM): sheets are bonded to form an object * Directed energy deposition (LENS): focused thermal energy is used to fuse materials by melting as deposition occurs * Powder fired into a laser beam

Answer 157

How are ceramics made? Material prep: chemical, physical, morphological * Weigh materials, milling, add binder, spray dry, characterise powder Forming: process options, dimensional and density control * Dry powder: isostatic press, roll compaction, hot press * Casting: tape cast, slip cast, pressure cast * Plastic forming: extrusion, injection mould * Chemical vapor deposition Firing: kiln options, temp & time, refractory, atmosphere * Continuous, batch, atmosphere, vacuum, HIP, hot press Finishing: shape & tolerance, finish, features, assembly * Shaping: CNC grinding, laser machining, cutting * Surface treatment: metallizing, plating and glazing, coating * Assembly: brazing, solder, adhesive * Specialised: cleanroom assembly, inspection and test, materials R&D

Answer 158

Why use ceramics? Mechanical * Hardness * Rigidity * Toughness * Wear Chemical * Corrosion * Biocompatible * Ultra-pure * Inert (or active) Thermal * Shock & stability * Conductivity * Expansion * Creep Electrical * Resistivity * Conductivity * ESD – safe * Dielectric strength

Answer 159

What is hydrodynamic volume? It is an indication of the expansion factor alpha High alpha means it is a good solvent Solvent polymer interactions are higher than polymer polymer interactions

Answer 160

* Gel permeation chromatography (GPC) – MW distribution * Differential scanning calorimetry (DSC) – Thermal transitions * Thermogravimetric analysis (TGA) – Thermal stability * Ultraviolet-visible spectroscopy (UV/vis) – structure/composition * Fourier transform Infrared spectroscopy (FTIR) – structure/composition

Answer 161

Bio based polymers: * Polymer produced from renewable natural resources e.g. PLA, PHA Drop in bio-based polymers: * Chemically identical to conventionally sourced polymers, but are (at least partially) produced from biomass e.g. PET, PE from ethanol feedstocks (sugar cane) Polymers may be biodegradable: their properties deteriorate and may completely degrade under aerobic or anaerobic conditions * Bio based may or may not be biodegradable. * Tend to be starch based derived from potatoes or wood * Or protein based for biomedical applications Term bio polymers sometimes used to describe bio-compatible polymers suitable for biomedical applications * E.g. silicone rubber, polyethylene, PMMA Currently 2% of world production is bio-based polymers. However, it is increasing fast estimated 20% per year. Attention is focussing on a few polymers, particularly those showing potential for scale up and packaging.

Answer 162

What are the properties and applications of Starch * Blended with other polymers to make materials with range of properties * Lower starch content associated with improved properties but decreased biodegradation * Substitute for PE, PP and EPS * Food and agricultural applications: bags, packaging PLA * Physical properties similar to PS * Can be modified to resemble PE and PP * Grease resistance comparable to PET * Degrades by hydrolysis * Food and medical applications: plastic plates and knives and forks PHA * Comparable to PP * Can also substitute for PE and PVC * Degrades in composting and anaerobic conditions * Razors, toothbrushes, bags etc.

Answer 163

Production process of * Starch: * Wet milling of corn * Extrusion into TPS * Add water and plasticiser * Reactive blending into starch blend * Add PVA and PCL * PLA * Wet milling of corn into glucose * Fermentation into lactic acid * Polymerisation into PLA * PHA * Wet milling corn into glucose * Fermentation and extraction into PHA

Answer 164

Issues with biopolymers: * Intensive agriculture * Large scale monocultures * Agrochemical use * Irrigation * Capacity, competition with food production * Biopolymers cannot meet demand in near future * Energy requirements * Fossil fuels used for: synthetic fertilisers, pesticides, farm machines, lights, pumps, fans, heating, water * Cost * More expensive than conventional polymers * Disposal * Mechanical recycling * Bio polymers contaminate conventional recycling * Composting: home/industrial degrades into CO2 and water. * Biopolymers not always suitable for home composting * May not degrade in industrial composters or at all * Feedstock or chemical recycling * Energy recovery * Landfill * Bio polymers will generate methane if degradable in landfill * Performance

Answer 165

Future improvements: * Integrated system agriculture * More use of renewable * Alternative feedstocks * Crop waste is used but energy requirements tend to be higher * Consumer food waste: problems of contamination can be lower energy requirements * Improved farming practices * Reduction in agrochemicals * Reduction in fuel costs * Optimisation of polymer production processes

Answer 166

What are the advantages of fibre lasers? * Excellent heat management * High efficiency: low heat dissipation * High surface area/volume: helps heat removal * High mode quality * Highly directional and coherent output * Compact and robust * No re-alignment * Telecom leveraged

Answer 167

How does size affect properties? * Nanosized particles exhibit different properties than larger particles Properties: describe how the material acts under certain conditions Properties that often changes: * Optical: colour, transparency * Electrical: conductivity * Physical: hardness, boiling point * Chemical: reactivity, reaction rates Why do properties change? Four reasons: * Gravitational forces become negligible and electromagnetic forces dominate * Gravity is a function of mass * Electromagnetic are not affected by mass * Electromagnetic forces are 10^36 times stronger than gravity * Quantum mechanics is used to describe motion and energy instead of classical mechanics * Greater surface to volume ratios * Greater amount of substance comes into contact with surrounding material * Better catalysts * Random molecular motion becomes more important It is important to understand these factors when researching new materials and ways to manufacture goods from them

Answer 168

What is prepreg? What are the advantages and disadvantages? Prepreg: resign pre-impregnated reinforcement, typically thermoset epoxy UD tape for cure in autoclave, automatically laid up for aerospace applications Advantages Resin levels accurately set by supplier Uni directional (UD) fibre is aligned to structural loads Allows for complex lay ups in automated processes Cana use high viscosity matrices for high toughness and damage tolerance Disadvantages Higher material cost from multi-step process and cold supply chain Needs expensive tooling capable of withstanding high temps and pressures Debulking need on thicker laminates

Answer 169

What are the important parameters for successful bonding? * Design of the joint * Adhesive selection * Surface preparation * Substrate and conditions in service Why is viscosity important? * Dictates the application methods required for material use. * High viscosity can be difficult to remove * Low viscosity can flow to much and run off surfaces Thixotropy: indication of a material’s decrease in viscosity over time while under stress. Indicate an adhesives ability to fill gaps between substrates Predict a product’s resistance to sagging vertical surfaces

Answer 170

Why is lap shear strength important? * Gives a measure of ultimate load and a way of comparing adhesive strength * Cohesive failure: adhesive remains on both substrates, indicating a strong bond * Adhesive failure: adhesive remains on one substrate, indicating selection of the wrong adhesive for substrates Why is peel strength important? * Peel strength is a measure of a material’s ability to withstand vibration and stretching without deforming or breaking. * Important indication of an adhesive’s toughnessand ability to produce joints that can withstand difficult service conditions Tensile properties are measured by: * Elongation: amount of stretch required to break a specimen * Ultimate tensile strength Gel time, work life and pot life are terms used interchangeably to indicate: * The amount of time at room temperature from initial mixing until the mixture can no longer be stirred. * Gel time can be increased or decreased by cooling or heating the resin or hardener

Answer 171

What is AM? * AM is the layer by layer deposition of material to make a part * Additive manufacturing is a process where: * Digital 3D design data is used to build up a component in layers by depositing material. * 3D printing is increasingly used as a synonym for AM. * However, AM is more accurate in that it describes a professional production technique which is clearly distinguishing from conventional methods of material removal.

Answer 172

What are the drawbacks of AM? * Machine cost (barrier to entry, limited volume) * Material cost * Throughput * Quality * Process control * Increased validation and demonstration, supported by standards for certification and process operation

Answer 173

What are the different types of engineered ceramics? * Oxides: * Aluminas * Quartz/silicates * Yttria * Zirconias * Non oxides * Carbides * Nitrides Material properties * Harder and stiffer than steels * More heat and corrosion resistant than metals or polymers * Lower density than most metals and allows * Raw materials are plentiful * Display wide range of properties to facilitate use in different product areas

Answer 174

Applications of alumina: * Beverage valves: hardness, rigidity, strength, corrosion resistant and inert * Improved lifetime * Improved portion control * Improved product quality * Precision metering pumps: hard, rigid, strength, wear, corrosion resistant, biocompatible, inert * Accurate dosing and long life * Ceramic provides dimensional stability Applications of zirconia * Diesel engine injector link: hardness, strength, wear, corrosion resistant, thermal stability * Improved lifetime, reduced warranty claims, improved fuel economy Applications of carbides * Body armour: hardness, strength, weight * Lives saves, weight reduction, improved ballistic protection * Satellite mirrors: rigidity, strength, weight, thermal conductivity and expansion * Strong, stiff and lightweight * Temperature capability, ultra-fine finish Applications of nitrides * Hybrid bearings: hardness, strength, wear, corrosion resistant, inert * Higher speeds and throughput * Improved runout and part accuracy * Cooler operation, less downtime