Glossary
What is SPC?
Statistical Process Control
Definition
SPC — statistical process control — monitors a process’s quality characteristics with statistical tools, chiefly control charts, so drift is detected before defective product is made.
The core idea
Every process varies naturally. SPC separates natural (common-cause) variation from special-cause variation: when a point falls outside the control limits or shows an unusual pattern, something specific — such as tool wear — is probably at work.
Common tools
- X̄-R charts for the mean and range of samples
- p-charts for the proportion defective
- Cp and Cpk capability indices, which show how well the process fits within specification limits
Example
On a bottle line, one bottle’s weight is sampled every hour. When seven consecutive points sit above the mean, the operator checks the machine before it drifts out of specification.
SPC in Fidar
Control charts, Cp/Cpk and automatic certificates of analysis are designed into Fidar’s MES & Quality module.
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