What is SPC and SQC?

SPC or Statistical Process Control is a technique for improving quality within a process by statistically analysing the variables within the process and using this data to identify problem areas. The benefits to be gained from SPC include

• Improved product consistency.
• Improved customer satisfaction.
• Reduction in scrap.
• Reduction in rework.

When selecting variables to be monitored when using SPC, it is usual to begin with those variables that are a measure of the quality of the product (those variables of most concern to the customer). These may be things such as the weight, size, density, resistance, colour, etc. of the finished product. Monitoring these variables will give an indication of overall process performance and will highlight the need for the further application of SPC to the variables involved in the manufacture of the product.

It is crucial to minimise the accumulation of variability within a process, so when applying SPC you should start as early in the process as possible beginning with the raw materials if possible. A highly variable raw material (e.g. the grade or purity of the material) may be introducing factors into the process that can not be corrected further down the production line (at least economically).

The measurement of some values, particularly those relating to the quality of the finished product, may be beyond the scope of the Prodigy system. Indeed, some measurements may come from laboratory tests. Prodigy SPC allows both data collected by Prodigy and data obtained from external sources to be analysed.

What is SQC?
SQC is an acronym for Statistical Process Control. Whereas SPC ususally refers to on line near real time analysis of a process, SQC is used for off line analysis of historic data to determine factors that effect quality.