INTERMITTENT FLOW PROCESSES
This process is very suitable for a large variety of output, each output taking a different route and hence operations, with different time requirements and sequence. In this process the different outputs are called batches or lots. These follow a different processing route through the facilities. Here the production is split into a series of manufacturing stages or operation. Each operation is completed on each one of the single items being made, before the next operation is started.
The characteristics of intermittent form are as follows.
1. It is suitable when the output variety is large and the volumes are low.
2. It is flexible in approach since it uses general purpose machines for a variety of outputs.
3. The transformation process is organized around standard operations in the intermittent form (e.g. in a bank we have saving accounts counter, current account counter, cash counter, advances and time deposits departments etc.,) here each functional group is a specialist group.
4. Material handling here depends upon standard operations, and there is a work-in-process (WIP) inventory.
Under this type of manufacturing, the product is processed in lots rather than on a continuous flow basis. The product design and the machines set-up are tailor-made to a particular lot production. It is the duty of the works manager or plant engineer to determine the economic manufacturing lot size for each component part, sub-assembly or assembly. Unlike the continuous flow production, the product design and the machine set-up changes as the lot changes. Generally, the general machines are used in this type of manufacturing. It is desirable to arrange the machines on the process layout basis rather than on product layout which is more suited to continuous manufacturing.
The problem of production planning and control are relatively more complex as compared to continuous manufacturing. The routing function changes along with the change in the lot to be manufactured. The scheduling function is performed in the light of the jobs on hands, their stage of completion, commitment for completion etc. Unlike continuous manufacturing, it is relatively difficult to maintain the balance in the production line. The chances of waiting, rushing and bottlenecks are more, resulting in either idle capacity or pressure on existing production capacity. The dispatching also becomes a complex function.
The jobs assignments to men and machines necessitate the up-to-date information about their existing and probable work loads. The investments in the inventories tend to be high due to the maintenance of reservoirs of materials in the sub-stores and the prolonged operating cycle. Due to all these factors, the follow-up function is difficult as well as inevitable in the intermittent manufacturing.