COMPARITIVE PROCESS SELECTION IN MANUFACTURING
Volume Vs Variety
It could be considered as a continuum (volume-variety). One extreme end of this continuum shows very high variety (and hence very low volume). The other extreme is that of low product variety but very high volumes. Variety requires skilled technicians, general purpose machines, and complex Production Planning Control (PPC). High volumes require automation, mass-producing special machines and simple PPC.
Produce to Stock Vs Produce to order
One important consideration affecting selection of the process is that of making production first for storing in the storage for selling or receiving an order first from the customers, and then starting the production process. Standardization and variety reduction leads to batch production which forms the inventory from which stocks to sell are drawn, is replenished by further batch production once it reaches a minimum pre-determined level. The system produces here in anticipation of demand. There is no waiting time involved for the customer. Such products carry inventories. The risk is much more in the case of perishable products and short shelf-life products.
Produce to order is customized producing where the manufacturing process or operation follow the receipt of customerâ€™s order. Yes, here there is a waiting time for the customer (delivery date). The time is proportional to the lead time of the operational process. Non-inventory services are always produced to order, taking care that the waiting time for the customer is as short as possible.
There could be a combination of both these: components and spares are produced to stock, and the assembly is carried out to order. In a restaurant, dishes are in the semi-cooked form (produced to stock) and are converted to dishes to be served on customer demand (produce-to-order).
Output Characteristics Vs Process selection
The selection of process from project type, intermittent type, continuous type or continuous-process type depends upon the characteristics of the output. Unique non-repetitive output like ship building requires project form. Assembly of ceiling fans may require interrupted form. Here the batch size is large. However, TV assembly may use continuous form, though interrupted form may be used if the batch size is small. There are products with no variety at all and are like genetic commodities — fertilizers, sugar, cement and others. They require a continuous process form.
Services may be on project form like that of an architect. Services from government are interrupted form. In high volume services, continuous form is used.