The whole point of process design is to make sure that the performance of the process is appropriate for whatever it is trying to achieve. For example, if an operation competed primarily on its ability to respond quickly to customer requests, its processes would need to be designed to give fast throughput times. This would minimize the time between customers
Process design and product /service design should be considered together
requesting a product or service and their receiving it. Similarly, if an operation competed on low price, cost-related objectives are likely to dominate its process design. Some kind of logic should link what the operation as a whole is attempting to achieve and the performance objectivesof its individual processes. This is illustrated in Table 4.1.
Operations performance objectives translate directly to process design objectives as shown in Table 4.1. But, because processes are managed at a very operational level, pro- cess design also needs to consider a more ‘micro’ and detailed set of objectives. These are largely concerned with flow through the process. When whatever are being ‘processed’ enter a process they will progress through a series of activities where they are ‘transformed’ in some way. Between these activities they may dwell for some time in inventories, waiting to be transformed by the next activity. This means that the time that a unit spends in the process (its throughput time) will be longer than the sum of all the transforming activities that it passes through. Also the resources that perform the processes activities may not be used all the time because not all units will necessarily require the same activities and the capacity of each resource may not match the demand placed upon it. So neither the units moving through the process, nor the resources performing the activities may be fully utilized. Because of this the way that units leave the process is unlikely to be exactly the same as the way they arrive at the process. It is common for more ‘micro’ performance flow objectives to be used that describe process flow performance. For example:
● Throughput rate(or flow rate) is the rate at which units emerge from the process, i.e. the number of units passing through the process per unit of time.
● Throughput timeis the average elapsed time taken for inputs to move through the pro- cess and become outputs.
● The number of units in the process (also called the ‘work in process’ or in-process inventory), as an average over a period of time.
● The utilizationof process resources is the proportion of available time that the resources within the process are performing useful work.
Table 4.1 The impact of strategic performance objectives on process design objectives and performance
Operations performance objective
Quality
Speed
Dependability
Flexibility
Cost
Some benefits of good process design
• Products and services produced
‘on-specification’
• Less recycling and wasted effort within the process
• Short customer waiting time
• Low in-process inventory
• On-time deliveries of products and services
• Less disruption, confusion and rescheduling within the process
• Ability to process a wide range of products and services
• Low cost / fast product and service change
• Low cost / fast volume and timing changes
• Ability to cope with unexpected events (e.g. supply or a processing failure)
• Low processing costs
• Low resource costs (capital costs)
• Low delay and inventory costs (working capital costs)
Typical process design objectives
• Provide appropriate resources, capable of achieving the specification of product of services
• Error-free processing
• Minimum throughput time
• Output rate appropriate for demand
• Provide dependable process resources
• Reliable process output timing and volume
• Provide resources with an appropriate range of capabilities
• Change easily between processing states (what, how, or how much is being processed)
• Appropriate capacity to meet demand
• Eliminate process waste in terms of – excess capacity
– excess process capability – in-process delays – in-process errors
– inappropriate process inputs
Process design should reflect process objectives
Throughput rate
Throughput time
Work in process
Utilization
Environmentally sensitive design
With the issues of environmental protection becoming more important, both process and product/service designers have to take account of ‘green’ issues. In many developed countries, legislation has already provided some basic standards which restrict the use of toxic materials, limit discharges to air and water, and protect employees and the public from immediate and long-term harm. Interest has focused on some fundamental issues:
● The sources of inputs to a product or service. (Will they damage rainforests? Will they use up scarce minerals? Will they exploit the poor or use child labour?)
● Quantities and sources of energyconsumed in the process. (Do plastic beverage bottles use more energy than glass ones? Should waste heat be recovered and used in fish farming?)
● The amounts and type of waste materialthat are created in the manufacturing processes.
(Can this waste be recycled efficiently, or must it be burnt or buried in landfill sites? Will the waste have a long-term impact on the environment as it decomposes and escapes?)
● The life of the product itself. It is argued that if a product has a useful life of, say, twenty years, it will consume fewer resources than one that only lasts five years, which must therefore be replaced four times in the same period. However, the long-life product may require more initial inputs, and may prove to be inefficient in the latter part of its use, when the latest products use less energy or maintenance to run.
● The end-of-life of the product. (Will the redundant product be difficult to dispose of in an environmentally friendly way? Could it be recycled or used as a source of energy? Could it still be useful in third-world conditions? Could it be used to benefit the environment, such as old cars being used to make artificial reefs for sea life?)
When Daimler-Chrysler started to examine the feasibility of the Smart town car, the challenge was not just to examine the economic feasibility of the product but also to build in environmental sensitivity to the design of the product and the process that was to make it. This is why environmental protection is now a fundamental part of all production activities in its ‘Smartville’ plant at Hambach near France’s border with Germany. The product itself is designed on environmentally compatible principles. Even before assembly starts, the product’s disassembly must be considered. In fact the modular construction of the Smart car helped to guarantee economical dismantling at the end of its life. This also helps with the recycling of materials. Over 85 per cent of the Smart’s components are recyclable and recycled material is used in its initial construction. For example, the Smart’s instrument panel comprises 12 per cent recycled plastic material. Similarly, production processes are designed to be ecologically sustainable. The plant’s environmentally friendly painting technique allows less paint to be used while maintaining a high quality of protection. It also involves no solvent emission and no hazardous waste, as well as the recycling of surplus material. But it is not only the use of new technology that contributes to the plant’s ecological credentials. Ensuring a smooth and efficient movement of materials within the plant also saves time, effort and, above all, energy. So, traffic flow outside and through
Short case
Ecologically smart
2the building has been optimized, buildings are made accessible to suppliers delivering to the plant, and conveyor systems are designed to be loaded equally in both directions so as to avoid empty runs. The company even claims that the buildings themselves are a model for ecological compatibility. No construction materials contain formaldehyde or CFCs and the outside of the buildings are lined with ‘TRESPA’, a raw material made from European timber that is quick to regenerate.
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Designers are faced with complex trade-offs between these factors, although it is not always easy to obtain all the information that is needed to make the ‘best’ choices. For example, it is relatively straightforward to design a long-life product, using strong material, over-designed components, ample corrosion protection, and so on. But its production might use more materials and energy and it could create more waste on disposal. To help make more rational decisions in the design activity, some industries are experimenting with life cycle analysis.
This technique analyses all the production inputs, the life-cycle use of the product and its final disposal, in terms of total energy used (and more recently, of all the emitted wastes such as carbon dioxide, sulphurous and nitrous gases, organic solvents, solid waste, etc.). The inputs and wastes are evaluated at every stage in its creation, beginning with the extraction or farming of the basic raw materials. The short case ‘Ecologically smart’ demonstrates that it is possible to include ecological considerations in all aspects of product and process design.