A2 Processes & Layouts

Question 1

Demands placed on modern manufacturing systems

Answer 1

Increase in product variety
Decrease in product quantity (esp. in HVM)
Increase in customer expectations
Reduction in time to market
New/better materials
Global production

Question 2

Aims of good plant layout

Answer 2

Organise factory for simplicity to improve throughput & efficiency
Locate equipment within a department
Locate departments & facilities within a site
Reduce overhead cost for production

Question 3

Criteria for good plant layout

Answer 3

Maximise: flexibility of machines/layout, use of volume (quantity), coordination between departments, visibility of people & machines, accessibility of machines, security & safety
Minimise: distance & handling of parts, discomfort of workers
Efficient & smooth process flow
Identification of workers

Question 4

Advantages of good plant layout

Answer 4

Minimise process cost & time
Reduce movement & handling
Improve effectiveness of all work processes
Simplify supervision & control
Accommodate changes readily
Maximise output via effective use of space & resources
Encourage morale of workforce

Question 5

2 types of process layout & types of production typically used in each

Answer 5

Process (batch/job), product (flow production)

Question 6

Process layout A&D

Answer 6

A: Flexible use of equipment & workforce, low investment cost, specialised supervision
D: Large volume of WIP, complexity in planning/control, long production time, higher skill level required in workforce

Question 7

Product layout A&D

Answer 7

A: Operations arranged in planned sequence, less material handling, much reduced WIP, short production time, simplified planning/control/supervision, lower worker skill level
D: Lower flexibility, production pace determined by slowest operation, breakdown of 1 machine leads to production stoppage, mundane repetitive tasks, expensive automation

Question 8

Group technology

Answer 8

Manufacturing concept that takes advantage of similarities (geometry, process) among parts

Question 9

Cellular manufacturing

Answer 9

Using several machine cells that can produce different parts with similarities

Question 10

GT & Cellular manufacturing As

Answer 10

Standard part design
Minimise design duplicaiton
Estimate cost of new products easily
Tools & jigs standardised due to part families
Reduce part flow/movement/WIP

Question 11

GT & Cellular manufacturing Ds

Answer 11

Difficult to schedule jobs to large variety

Question 12

FMS (flexible manufacturing systems)

Answer 12

Extension of GT & cellular manufacturing to encompass whole factory

Question 13

FMS As

Answer 13

Produce parts randomly at low unit cost & in small batch sizes e.g. 1
Reduced direct labour & inventories
Improved productivity with high MUR (machine utilisation rate)
Reduced production lead time
Reduced WIP

Question 14

CIM (computer integrated manufacturing)

Answer 14

Extension of FMS to encompass whole manufacturing organisaiton

Question 15

CIM As

Answer 15

Responsive to shorter product life cycle & changing product demand
Uniformity through better process control
Better use of resources
Better control of planning & scheduling & manufacturing

Question 16

CIM Ds

Answer 16

Expensive
Long periods of introduction
Benefits not immediately visible
Lead to fundamental organisational changes

Question 17

Examples of job production

Answer 17

Low tech - hairdressing, tailoring
High tech - bridges, ship building

Question 18

Batch production

Answer 18

Seasonal/limited edition products

Question 19

Flow production

Answer 19

Mass produced goods e.g. cars, household goods, food products

Question 20

Job production

Answer 20

Task handled by single/group of workers
Resources allocated for duration of project
1-off project, no expectation of identical repeat order
Cost of production includes design, production, tooling, admin cost & all overheads

Question 21

Batch production

Answer 21

Specific production quantity with set time intervals
Expect future orders
Orders & amount of stock determine production quantity
Cost of production spread over whole batch

Question 22

Flow production

Answer 22

Continual orders of near identical products
At each production stage - same timing of operations, equipment provided
Cost of production spread over long period of production

Question 23

Process planning

Answer 23

Function within manufacturing facility that determines which processes are used to convert parts form initial to final form based on engineering designs
Process plan then generated & used by schedules & machine operators

Question 24

Info on process plan

Answer 24

Features to manufacture
Tools/machines to use
Manufacturing time of each feautre

Question 25

Main steps in process planning

Answer 25

Geometry analysis, raw material selection, process selection, process detailing
Setup, fixture planning & design
Process plan analysis & evaluation

Question 26

What is variant CAPP?

Answer 26

Computer aided process planning
Assume similar parts have similar process plans
Software identifies similar parts, retrieves them & edits plans to suit requirements of each part
GT used
Only modifies existing plans

Question 27

What is generative CAPP?

Answer 27

Computer aided process planning
Automatic synthesis of a plan for a new part rather than human decision making
Plan made using info from manufacturing process database
Same procedure as variant CAPP but quicker, generates completely new plans

Question 28

Workflow

Answer 28

Sequence of tasks/arrangement of processes a product undergoes as it’s made
Each product has flowed through a sequence of production processes having work performed on it

Question 29

Precedence diagrams

Answer 29

Illustrate workflow required to make a product & identifies manufacturing lead time

Question 30

Manufacturing lead time

Answer 30

Total manufacturing time from start to finish incl. processing, setup, waiting & idle time

Question 31

Relationship chart

Answer 31

Analyses plant layout in manufacturing organisation to best locate machines/departments based on criteria such as general material flow & safety

Question 32

Travel charts

Answer 32

Quantitatively illustrate pattern & amount of part movement between departments/machines to identify critical path of production process

Question 33

Line balancing

Answer 33

Balance operations at various stages of a flow line to ensure even loading on each stage, spread tasks evenly across workstations, minimise job complexity/errors/bottlenecks/machines used

Question 34

Line balancing As

Answer 34

Precedence requirements achieved, idle time reduced, production capacity & rate improved

Question 35

How to achieve line balancing

Answer 35

Rearrange manufacturing processes assigned to which workstations so total time at each workstation is equal

Question 36

Work Content

Answer 36

All work completed on line/total production time for 1 unit/batch, made up of service & repositioning time

Question 37

Service time

Answer 37

Time spend processing e.g. drilling

Question 38

Repositioning time

Answer 38

moving parts/tools/people

Question 39

Cycle time

Answer 39

Service + repositioning time
Time between products being finished when line is running

Question 40

Production rate

Answer 40

amount of products produced per unit time to meet demand

Question 41

Line efficiency

Answer 41

ratio between actual operating time & ideal operating time - working time available
Measures typical time lost due to unexpected machine breakdowns, power cuts
Value derived from experience of similar lines

Question 42

Balancing efficiency

Answer 42

ratio between total work content & total available service time - accounts for idle time

Question 43

Why difference between ideal no. of workstations required & actual no.?

Answer 43

time wasted positioning parts & imperfect balancing so actual time available to work is shorter so more workers required to meet production rate