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SPC...
Statistical Process Control
The technique where samples are pulled from a process at periodic intervals and measured by calibrated instruments and data points are plotted on an Xbar R chart over a period of weeks. Analyzing the data and calculating upper and lower control limits, one can easily tell that the process is in-control or out-of-control.
If the process is out-of-control, other tools are used to analyze the process, Pareto Analysis, Cause and Effect Diagrams, and others to pinpoint the variation and then change the process so that the variation is eliminated.
Variation can come from the following sources:
- Machines
- Methods
- Materials
- Environment
- People
No two machines operate the same way based upon how they were manufactured and the raw materials that were used in the manufacturing process. Operators no matter how well trained, operated machines differently from one another as well.
Methods include how we operate and provide maintenance on the machine and the tools that we use. Tools that need to be calibrated need to have that happen routinely to make sure they are still holding their calibrations.
Raw materials vary from one supplier to another supplier for the same reasons that I have already listed. They need to be check consistently and statistically to make sure they have not varied beyond the required specs.
For instance, a magic marker. If the inner dimensions of inside the marker cap are too much wide than the outer dimensions of the barrel they are to attach too. The cap will be too loose to fit properly, and the ink will dry out quicker than promised.
Environment pertains to the temperature as well as the morale of the people working there. Too hot, too cold, too dry, too humid all those conditions can influence the variation produced by the machine on the raw materials.
Lastly, the people or one's employees. The main problem here is lack of training followed by morale and attitude and bringing problems from home into the workplace.
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