Statistical process control

Essay by gcolUniversity, Master'sB-, November 2002

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"Properly applied, S.P.C. is virtually foolproof. It is simple to use, involves little or no complicated mathematics, and almost guarantees to pay for itself in saved effort." (Wilson)


Outputs from a manufacturing process will vary - perhaps minutely - from the exact specification, and deliveries from a service will differ in quality and substance. These inconsistencies in quality require constant monitoring to see if they are random, regular, haphazard, important, or evidence of a problem. The monitoring and controlling should be applied to the process not the product, and can be greatly facilitated by S.P.C.

Process control means controlling production by checking its quality while the work is still in process. Implementing S.P.C. means applying statistical techniques and analysis to that control function. As S.P.C. is about measuring the quality of work in process, its implementation is usually allied to techniques related to quality systems management.

Advantages of implementing S.P.C.

Chaudhry and Higbie report the following benefits from applying S.P.C. in a chemical plant:

·improved production efficiency

·a more consistent product

·greater reliability - shifting control efforts from product to process

·greater ease in pinpointing problem occurrences

·provision of a usable measure of performance

·clearer communication of objectives

·improved customer relations.

Disadvantages of implementing S.P.C.

S.P.C. can take time to apply rigorously but applications do show that there are few, if any, disadvantages to S.P.C. Its application must remain relevant and useful, rather than becoming a system 'for its own sake.'

Action checklist

1. Plan the programme and communicate organisation-wide

Firstly, you need to get the overall project context right with those over-arching elements essential to all successful change programmes:

·securing proactive and continuous top management commitment

·appointing the right project leader and obtaining the right expertise

·establishing flexible time-frames and broad resource requirements

·communicating regularly with the...