Simple and simultaneous gives a rapid response

Citation

Loughlin, C. (1998), "Simple and simultaneous gives a rapid response", Assembly Automation, Vol. 18 No. 1. https://doi.org/10.1108/aa.1998.03318aaa.001

Simple and simultaneous gives a rapid response

Simple and simultaneous gives a rapid response

Just-in-time (JIT) delivery is no longer the hot topic of conversation that it once was. This is not because the concept has failed but more due to its success and widespread adoption. Companies now expect their suppliers to offer fast and reliable deliveries, and have reduced their stockholding capability accordingly. Warehouses of components have now been replaced by small buffer stock areas and a company's precious cash is no longer tied up in dormant inventory.

The dangers of JIT are obvious and I am sure that everyone in manufacturing is in favour of stockholding as long as it is not they who are doing the holding. We all assume that the company further down the chain has good stock so that we do not have to.

The issue is not concerned with JIT from a delivery point of view, but is concerned with the assembly mechanisms that we need to have in place so that we do not end up being the ones who have to carry the stock. Our theme "Rapid response manufacturing" covers the systems that enable a manufacturer of, say, 100 components to switch from producing one component to another almost at will. To really minimize stockholding you need to be able to operate down to a batch size of one. This may, initially, seem impractical; however, it is worthwhile working through the implications, assuming that such a facility was available to you. If the resulting benefits are worthwhile then it may lead you to find ways of achieving this unit batch size goal, which at first appeared so impractical.

An important consideration when designing for a batch size of one is of course what happens if you get an order for 1,000? Being able to make a single component is all very well but if it takes as long to do that as a more dedicated machine might take to make 500, then you will not stay in business too long. How then do we balance the need for small batch sizes with the commercial constraints that demand high productivity? To me the answer lies in simultaneous manufacturing or a sequential series of flexible systems.

If, for example, you have one robot arm and surround it with a plethora of parts-feeding mechanisms, carousels and inspection systems, then it may well be very flexible and be able to make a wide variety of widgets in random order ­ but it will never be able to do it very quickly. It does not matter how fast the robot is, it will always look slovenly when compared with a dedicated assembly system. If you are making high value products for which demand is only a few units a year then this sort of system will be fine, but if you need flexibility as well as high productivity you need simultaneous manufacturing.

Such a concept is not new and there are several examples, such as the Sony SMART system, that have been operating for years. In these systems parts progress down a line and pass by stations that are able to perform a particular task, such as applying glue or inserting a component quickly and efficiently. A particular assembly will only require a subset of the available operations to be performed on it and so may well skip past ten out of 50 workstations; however, each of the remaining 40 operations will be performed at the same time as the others, on parts further up or down the line, and so the productivity of the system as a whole will be very high. It will also have an output that is governed by the index rate of the conveyor so that the rate of production will be constant, regardless of the mix of parts that are being processed.

This is not a new idea; however it is a concept that is often forgotten and I consider that it is key to our achievement of rapid response manufacturing goals.

Clive Loughlin