Legal and General’s modular housing process 4
5.3 Diagnostic question: Are process layouts appropriate?
There is little point in having a well-sequenced process if in reality its activities are physically located in a way that involves excessive movement of materials, information or customers.
Usually, the objective of the layout decision is to minimise movement, but, especially in an information-transforming process where distance is largely irrelevant, other criteria may dominate. For example, it may be more important to lay out processes such that similar activities or resources are grouped together. So, an international bank may group its foreign exchange dealers together to encourage communication and discussion between them, even though the ‘trades’ they make are processed in an entirely different location. Some high- visibility processes may fix their layout to emphasise the behaviour of the customers who are being processed.
Layout should reflect volume and variety
Again, the layout of a process is determined partly by its volume and variety characteristics.
When volume is very low and variety is relatively high, ‘flow’ may not be a major issue. For example, in telecommunications satellite manufacture each product is different, and because products ‘flow’ through the operation very infrequently, it is not worth arranging facilities to minimise the flow of parts through the operation. With higher volume and lower variety, flow becomes a far more important issue. If variety is still high, however, an entirely flow- dominated arrangement is difficult because there will be different flow patterns. For example, a library will arrange its different categories of books and its other services partly to minimise the average distance its customers have to ‘flow’ through the operation. But, because its
OPERATIONS PRINCIPLE Resources in low-volume, high- variety processes should be arranged to cope with irregular flow.
OPERATIONS PRINCIPLE Resources in high-volume, low-variety processes should be arranged to cope with smooth, regular flow.
Figure 5.5 A product–process matrix of the meter installation process showing different positions
‘Natural’ line of fit
Excess process rigidity
Excess process exibility
A B
C X
Process positions for the water meter example
Cost performance
Flexibility performance
High Low
Low Variety
High Volume
Diverse/
complex
Repeated/
divided
Intermittent
Continuous Process
tasks Process
5.3 Diagnostic question: Are process layouts appropriate ■ 173
customers’ needs vary, it will arrange its layout to satisfy the majority of its customers (but perhaps inconvenience a minority). When the variety of prod- ucts or services reduces to the point where a distinct ‘category’ with similar requirements becomes evident but variety is still not small, appropriate resources could be grouped into a separate cell. When variety is relatively small and volume is high, flow can become regularised and resources can be positioned to address the (similar) needs of the products or services, as in a classic flow line.
Most practical layouts are derived from only four basic layout types that correspond to different positions on the volume–variety spectrum. These are illustrated diagrammatically in Figure 5.6 and are described here.
Fixed-position layout
Fixed-position layout is in some ways a contradiction in terms, since the transformed resources do not move between the transforming resources. Instead of materials, information or cus- tomers flowing through an operation, the recipient of the processing is stationary and the equipment, machinery, plant and people who do the processing move as necessary. This could be because the product or the recipient of the service is too large to be moved conveniently, or it might be too delicate to move, or perhaps it could object to being moved; for example:
• power generator construction – the product is too large to move;
• open-heart surgery – patients are too delicate to move;
• high-class restaurant – customers would object to being moved to where food is prepared.
5.3 Diagnostic question: Are process layouts appropriate?
There is little point in having a well-sequenced process if in reality its activities are physically located in a way that involves excessive movement of materials, information or customers.
Usually, the objective of the layout decision is to minimise movement, but, especially in an information-transforming process where distance is largely irrelevant, other criteria may dominate. For example, it may be more important to lay out processes such that similar activities or resources are grouped together. So, an international bank may group its foreign exchange dealers together to encourage communication and discussion between them, even though the ‘trades’ they make are processed in an entirely different location. Some high- visibility processes may fix their layout to emphasise the behaviour of the customers who are being processed.
Layout should reflect volume and variety
Again, the layout of a process is determined partly by its volume and variety characteristics.
When volume is very low and variety is relatively high, ‘flow’ may not be a major issue. For example, in telecommunications satellite manufacture each product is different, and because products ‘flow’ through the operation very infrequently, it is not worth arranging facilities to minimise the flow of parts through the operation. With higher volume and lower variety, flow becomes a far more important issue. If variety is still high, however, an entirely flow- dominated arrangement is difficult because there will be different flow patterns. For example, a library will arrange its different categories of books and its other services partly to minimise the average distance its customers have to ‘flow’ through the operation. But, because its
OPERATIONS PRINCIPLE Resources in low-volume, high- variety processes should be arranged to cope with irregular flow.
OPERATIONS PRINCIPLE Resources in high-volume, low-variety processes should be arranged to cope with smooth, regular flow.
Figure 5.6 Different process layouts are appropriate for different volume–variety combinations Fixed-position
layout
Functional layout
Cell layout
Product layout High
Low
Low Variety
High Volume
Based around process resources
Based around products/services
Process layout
Case example
Reconciling quiet and interaction in laboratory layout
6The layout of scientific laboratories is rarely straightfor- ward. Not only can different areas of a laboratory require very different service needs (temperature, extraction, lack of vibration, etc.) but also the types of work that all sci- entists engage in can have different needs. On one hand, there is active experimentation; on the other hand, there are times when quiet reflection is vital. Moreover, different individuals have different preferred working patterns. The conversations, discussions and, sometimes noisy, debate between some researchers can both irritate and distract other staff who prefer somewhere quiet to think and
write up their work. Even in prestigious and high-profile research operations, this conflict can be difficult to recon- cile. For example, some of the researchers working at the Francis Crick laboratory in central London complain that its open-plan layout, designed to encourage collabora- tion, makes it difficult to concentrate on their work. Some people like the background noise, while others prefer total silence, although many agree that the layout has been extremely successful in terms of promoting ad hoc meet- ings and has created new collaborations. Professor Alan Penn, who has been investigating how open-plan layouts
Figure 5.7 Example of an improved laboratory layout that reduces the degree of interference between different types of work (conversations and writing)
Original layout for laboratory
Quiet area
for writing
Scientists working by
window
Work bench
Scientists move round lab next
to quiet area
Main corridor
Conversations between scientists tend to occur close to the ‘quiet area’,
interfering with colleagues’ work
Work bench
Work bench
Work bench
Quiet area
for writing
Scientists working by
window
Work bench
Main corridor
Conversations now tend to occur
close to the entrance, without
interfering with colleagues Work bench
Work bench
Work bench Improved laboratory layout
with less disturbance
Scientists move round lab away from quiet area
5.3 Diagnostic question: Are process layouts appropriate ■ 175
(for example, those in advertising agencies or science laboratories) affect behaviour, points out how designing laboratories with busy circulation spaces allows scientists from different research groups to effectively share ideas.
People walking around can stop and join a conversation in the doorway of a laboratory. Conversations inside the laboratory, when they are next to where the relatively high-flow movement along the corridor occurs, lead to discussions between research groups.
Figure 5.7 illustrates how laboratory design can, to some extent, reduce the conflict between the benefits of interaction and the need for quiet. The conventional layout on the left allows potentially disruptive conversa- tions to interfere with quiet areas. The marginally mod- ified layout on the right encourages conversations to happen closer to the entrance, without interfering with colleagues.
Functional layout
Functional layout is so called because the functional needs and convenience of the transform- ing resources that constitute the processes dominate the layout decision. In functional layout, similar activities or resources (or those with similar needs) are located together. This may be because it is convenient to group them together, or that their utilisation can be improved that way. It means that when materials, information or customers flow through the operation, they will take a route from activity to activity according to their needs. Usually, this makes the flow pattern in the operation complex. Examples of process layouts include:
• Hospitals – some processes (e.g. radiography equipment and laboratories) are required by several types of patient.
• Machining the parts for aircraft engines – some processes (e.g. heat treatment) need special- ist support (heat and fume extraction); some processes (e.g. machining centres) require the same technical support from specialists; some processes (e.g. grinding machines) get high machine utilisation as all parts that need grinding pass through a single grinding section.
• Supermarkets – some products, such as 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. Others, such as the areas holding fresh vegetables, might be together because that way they can be made to look attractive to customers.
Cell layout
A cell layout is one where materials, information or customers entering the operation are pre- selected (or preselect themselves) to move to one part of the operation (or cell) in which all the transforming resources, to meet their immediate processing needs, are located. Internally, the cell itself may be arranged in any appropriate manner. 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 that characterises 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 producing parts for one particular cus- tomer 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, etc., for their lunch. These products are often located close together in a ‘cell’ for the convenience of these customers.
• 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
Product layout
Product layout involves locating people and equipment entirely for the convenience of the transformed resources. Each product, piece of information or customer follows a prearranged route in which the sequence of required activities corresponds to the sequence in which the processes have been located. The transformed resources ‘flow’ along a ‘line’. This is why this type of layout is sometimes called flow or line layout. Flow is clear, predictable and therefore relatively easy to control. It is the high volume and standardised requirements of the product or service that allow product layouts. Examples of product layout include:
• Car assembly – almost all variants of the same model require the same sequence of processes.
• Self-service cafeteria – generally the sequence of customer requirements (starter, main course, dessert, drink) is common to all customers, but layout also helps control customer flow.
Layout selection
Getting the process layout right is important, if only because of the cost, difficulty and disrup- tion of making any layout change. It is not an activity many businesses would want to repeat very often. Also, an inappropriate layout could mean that extra cost is incurred every time an item is processed. But more than this, an effective layout gives clarity and transparency to the flow of items through a process. There is no better way of emphasising that everyone’s activi- ties are really part of an overall process than by making the flow between activities evident to all participants in the process.
One of the main influences on which type of layout will be appropriate is the nature of the process itself, as summarised in its ‘process type’. There is often some confusion between process types and layout types, but they are not the same thing. Process types were described earlier in the chapter and indicate a broad approach to the organisation and operation of a pro- cess. Layout is a narrower concept but is very clearly linked to process type. Just as process type is governed by volume and variety, so is layout. But for any given process type there are usually at least two alternative layouts. Table 5.1 summarises the alternative layouts for particular pro- cess types. Which of these is selected, or whether some hybrid layout is chosen, depends on the relative importance of the performance objectives of the process, especially cost and flexibility.
Table 5.2 summarises the advantages and disadvantages.
Manufacturing
process type Potential layout types Service process type
Project Fixed-position layout Functional layout
Fixed-position layout Functional layout
Cell layout
Professional service
Jobbing Functional layout
Cell layout Functional layout
Cell layout Service shop
Batch Functional layout Cell layout
Mass Cell layout
Product layout Cell layout
Product layout Mass service Continuous Product layout
Table 5.1 Alternative layout types for each process type