Process configurations - products

The categorisation of production systems according to volume of output was discussed: project, job shop, batch and continuous. The Hayes and Wheelwright product - process matrix (1984) was then presented, showing the 'natural' positions of each of the configurations with regard to volume, variety and flexibility. When undertaking process design it is desirable to have some indication, perhaps by forecasts, of the likely level of demand for the product and the corresponding volume of process output to be generated.

With the knowledge of the approximate position along the job shop/batch/continuous spectrum, it is possible to narrow the range of process configurations to be devised and compared. If the demand is expected to be low, then large-batch or continuous systems need not be considered; their inflexibility would be unsuitable for the production of a variety of low-volume products, and their potential for low unit costs would be unattainable. Likewise, if the demand is expected to be high, job shop/small-batch systems would not be considered; their high unit costs would render the product uncompetitive, and their flexibility would be superfluous.

However, it is worth mentioning in passing that, under the heading of mass customisation, equipment suppliers are putting great efforts into the development of advanced computer-integrated manufacturing (CIM) systems which will provide the low unit costs of continuous systems and some of the flexibility of job shops. Consideration should also be given to the likely product life cycle curve and the expected durations of the start-up and rapid growth phases; for a product which, at maturity, reaches high volume, it may be necessary to change the type of production more than once during the product's life. Along with the change in volume and process flow type, as the product matures it is likely that the order winning criteria will also change, necessitating progressive amendment of the relevant measures of operational performance.