RK:Quality Methods

A strategy for using statistical process control .​

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1. A well set up process,                                                     (use Minitab to process data)
        accuracy and precision are vital before the process starts;  without that, there will
        be little hope of delivering today’s levels of quality.
    

2. … stable,                                                                  (use Infinity to process data)
        common causes must be controlled or eliminated, otherwise variability over  time
         will cause defects once more and charts will not be helpful.
    

3. … which checks critical features,                                                (use process map)
        are you sure that the parameters you measure are still critical?  
        Processes  have changed significantly over the last few years.
    

4. … with minimum quantities of samples,                           (use Minitab to estimate n)
        what science did you use to decide on sample sizes? You may be measuring
         too many samples and wasting money, or too few and making poor decisions.
    

5. … at suitable frequencies,                            (use history and risk from process map)
        is the frequency of checks decided by risk, or plant convenience?
    

6. … to ensure there is no significant change,                (use Infinity to process data)
        how many non-quality people realise that the qc check is not to check that
        the production is in specification; it is to check it has not changed since set-up.
    

7. … whilst continuously improving the process to eliminate variability.                                                                                             (use Minitab to process data)
        variability is a major cause of poor quality.