Lecture 11 & 12 Flashcards
Define what is meant by facility layout
- Refers to the size and shape of a faciliy as well as the relative locations and shapes of the functional areas (e.g., departments), equipment, workstations, storage spaces, aisles, and common areas (e.g., restrooms)
- Concerned with problems of
- Laying out a new facility
- Making changes in an existing facility
- Also called plant layout
- Usually associated with production plants
- Concerned with problems of
List the basic types of layouts.
- Fixed position - Project
- Process/Functional
- Jobbing
- Batch
- Product/Line
- Line
- Continous flow
- Cellular production
Explain fixed-Position layout.
(What is it suited for?)
(What are reasons for keeping product in one location?)
- Layout in which product remains in one location during fabrication, and workers and equipment are brought to the product.
- Suited to low production quantities and high product variety.
- Reason for keeping product in one location:
- Product is big and heavy
- Typical plants: assembly and fabrication
- Much manual labor
- Equipment is portable or mobile
- Hard to schedule - lots of parts from many places have to come to one place.
Examples of fixed position layout:
- Motorway construction – the product is too large to move.
- Open-heart surgery – patients are too delicate to move.
- High-class service restaurant – customers would object to being moved to where food is prepared.
- Shipbuilding – the product is too large to move.
- Mainframe computer maintenance – the product is too big and probably also too delicate to move, and the customer might object to bringing it in for repair.
Explain process (or functional) Layout
Layout in which equipment is arranged according to function.
- Suited to low and medium production quantities and medium to high product variety
- Different parts or products are processed through different operations in batches
- Each batch follows its own routing
- Material handling activity is significant
- From a supervision type of view it makes it easier for superivisors to supervise workers.
Problems with layout:
- Such factories down flow nicely. E.g. if you need to drill then mill then drill again, this will mean going back and forth to departments - inefficient.
- Large batch sizes are needed - because setup times tend to be high in process layouts - this leads to large queues.
Examples:
- Hospital – some processes (e.g. X-ray machines and laboratories) are required by sev- eral types of patient; some processes (e.g. general wards) can achieve high staff and bed utilization.
- Machining the parts which go into aircraft engines - some processes (e.g. heat treatment) need specialist support (heat and fume extraction); some processes (e.g. machining centres) require the same technical support from specialist setter–operators; some pro- cesses (e.g. grinding machines) get high machine utilization as all parts which need grind- ing pass through a single grinding section.
- Supermarket – some products, such tinned goods, are convenient to restock if grouped together. Some areas, such as those holding frozen vegetables, need the common tech- nology of freezer cabinets.
Explain product (or line) Layout.
Layout in which workstations and equipment are located along the line of flow of the work units.
- Suited to high production quantities and low product variety
- Work units typically moved by powered conveyor
- At each workstation, a small amount of the total work content is accomplished on each work unit
- Each station specializes in its task, thus achieveing high efficiency.
- (Hard to have a high variety in a product layout - unless you have different lines)
Problems:
- If you make some major design changes to model or make new model - this is a problem because the machines are designed to make a particular type of product - this makes this layout a high risk layout.
- One problem at one station - stops whole process - but can be a positive this prevents inventory build up.
What are the two types of combination layouts?
-
Fixed-position and process layout
- Shipyard - ships made in modules
- Parts fabricated in process layout
- Modules built in fixed-position layout.
- Shipyard - ships made in modules
-
Fixed-position and product layout
- Commerical airplanes (e.g., Boeing 747)
- Fabrication begins with fuselage and proceeds through 7 or so stations where specialized workers assemble parts and modules to airplane.
- Commerical airplanes (e.g., Boeing 747)
Explain cellular layout.
Layout in which work units flow between stations, as in a production line, but each stations can cope with a variety of part styles without the need for time-consuming changeovers
- Combination of product and process layouts
- Tries to combine efficiency of product layout with versatility of process layout
- Neither objective is achieved perfectly, but it is more efficient than a process layout and more versatile than a product layout.
- Based on principles of group technology.
Cellular layout is based on principles of group technology.
Explain what group technology is.
Group technology (GT) is a concept that currently is attracting a lot of attention from the manufacturing community. The essence of GT is to capitalize on similarities in recurring tasks in three ways:
- By performing similar activities together, thereby avoiding wasteful time in changing from one unrelated activity to the next.
- By standardizing closely related activities, thereby focusing only on distinct differences and avoiding unnecessary duplication of effort.
- By efficiently storing and retrieving information related to recurring problems, thereby reducing the search time for the information and eliminating the need to solve the problem again.
- In design engineering, parts can be classified by geometric similarities using codes that contain design attributes. The purpose could be to retrieve all parts with certain features, such as rotational parts with a length-to-diameter ratio of less than 2. If one of these fits the need at hand, the engineers can thereby avoid having to design a new part.
- Similarities between parts, captured in the GT code, can in like manner be used by manufacturing engineering, manufacturing, purchasing, and sales. For example, a manufacturer can drastically reduce the time and effort spent deciding how a part should be produced if this information is available for a similar part.
lots of info about it here:
https://hbr.org/1984/07/group-technology-and-productivity
Draw two different arrangements to illustrate process layout and cell layout.
Give the advantages/disadvantages of fixed position layout.
Advantages
- Very high mix and product flexibility
- Product not moved or disturbed
- High variety of tasks for staff
Disadvantages
- Very high unit costs
- Scheduling of space and activities can be difficult
- Can mean much movement of equipment and staff.
Give the advantages/disadvantages of process layout.
Advantages
- High mix and product flexibility
- Relatively robust in the case of disruptions
- Relatively easy supervision of transforming resources
Disadvantages
- Low facilities utilization
- Can have very high work-in-progress or customer queuing
- Complex flow can be difficult to control
Why is a facilities layout important?
- The ‘layout’ of an operation or process means how its transforming resources are positioned relative to each other and how its various tasks are allocated to these transforming resources. Together these two decisions will dictate the pattern of flow for transformed resources as they progress through the operation or process.
- It is an important decision because, if the layout proves wrong, it can lead to over-long or confused flow patterns, customer queues, long process times, inflexible operations, unpredictable flow and high cost. Also, re-laying out an existing operation can cause disruption, leading to customer dissatisfaction or lost operating time.
What are typical attributes of good layouts?
- To a large extent the objectives of any layout will depend on the strategic objectives of the operation, but there are some general objectives which are relevant to all operations. All layouts should be inherently safe; constituting no danger to either staff or customers.
- Generally, layout should (usually) minimize the length of flow through the operation and preferably make the flow clear.
- Staff should be located away from noisy or unpleasant parts of the operation and all equipment should be accessible. Layouts should achieve an appropriate use of space and allow for flexibility in the longer term
Explain cell layout (in terms of what the book defines it)
Give examples
- A cell layout is one where the transformed resources entering the operation are pre-selected (or pre-select themselves) to move to one part of the operation (or cell) in which all the trans- forming resources, to meet their immediate processing needs, are located. The cell itself may be arranged in either a functional or product layout (see next section). After being processed in the cell, the transformed resources may go on to another cell. In effect, cell layout is an attempt to bring some order to the complexity of flow which characterizes functional layout. Examples of cell layouts include:
- Some computer component manufacture – the processing and assembly of some types of computer parts may need a special area dedicated to the manufacturing of parts for one particular customer who has special requirements, such as particularly high quality levels.
- ‘Lunch’ products area in a supermarket – some customers use the supermarket just to pur- chase sandwiches, savoury snacks, cool drinks, yoghurt, etc., for their lunch. These prod- ucts are often located close together so that customers who are just buying lunch do not have to search around the store.
- Maternity unit in a hospital – customers needing maternity attention are a well-defined group who can be treated together and who are unlikely to need the other facilities of the hospital at the same time that they need the maternity unit.
Draw a product variety vs product quantity graph to illustrate the different plant types.
Explain production flow analysis for cell design
(Include rank cell ordering)
Production flow analysis for cell design
- Group parts into part families = type of part not individual part
- Identify processes
- Identify part families using the processes
- Develop a part-machine incidence matrix
- Perform clustering analysis to identify cells.
Rank order clustering
- Sort rows based on binary value (decreasing)
- Sort columns based on binary value
- Repeat process until no changes in sorting
- Use the clusters to create machine cells
What are the 4 levels of detail in plant layout.
- Site layout - shows building location on property
- Block layout - shows arrangement and sizes of departments in building
- Detailed layout - shows workstations and equipment in each department
- Workstation layout - indicates arrangement of equipment, workbench, WIP inventory, and worker floor space for each workstation type.
Systematic Layout Planning:
Explain Step 2 : Analyze Material Flows
Possible charting techniques to analyze material flows:
- Operation chart - shows sequence of processing, assembly, and inspection operations for products
- Flow process chart - shows processing steps and other details for parts production
- From-To chart - show quantities and directions of material flows between departments
- Part routing matrix - shows which operations each part is routed through during production.
Illustrate a From-To chart and a Flow-between chart.
Illustrate how an activity relationship chart is made.
Systematic Layout Planning:
Explain Step 4 : Activity Relationship Diagram
Graphucal means of displaying the closeness ratings among pairs of activities (departments)
- Uses nodes to represent activities
- Nodes are connected by lines indicating the closeness ratings
- Closeness ratings are identified by:
- Color
- Different types of lines
Systematic Layout Planning:
Explain Step 5 : Space Requirements
- Objective is to determine area requirements for each activity (department)
- Procedure:
- List all workstation types
- Identify by subscript i
- Determine floor space requirement for each station type
- Let Ai = area for station type i
- Determine number of stations for each type ni = smallest integer > WLi/ATi . Where WLi is the total workload that must be accomplished in a certain period, expressed in hrs of work per period; and ATi is the available time at the workstation in the same period.
- List all workstation types
Example of step 5:
Four types of workstations will be included in department 1. The floor area for each type, workloads per week and available times per week are given in the table below.
Determine the total area required for these four workstation types.
Systematic Layout Planning:
Explain Step 6 : Space Relationship Diagram
- Extension of activity relationship diagram in which nodes representing departments are now assigned areas that are proportional to areas calculated in the previous step.
- Shapes of nodes may be changed to fit the nodes into the diagram
- But relative positions of blocks remain as in the last iteration of the activity relationship diagram.
- Shapes of nodes may be changed to fit the nodes into the diagram
Systematic Layout Planning:
Explain Step 8 : Develop Block Layout
- Develop alternative layout plans based on space relationship diagram
- Different shapes and aspect rations
- Evaluate alternatives
-
Select the best
- Compromise between compting objectives, modifying considerations, and practical limitations.
Explain how to calculate the Adjacency Score.
Explain how you calculate the layout efficiency rating
Example:
Determine the adjacency score and layout efficiency rating for the black layout in slide 4.
