Filling in the columns
- Product characteristic: a feature of the part from the drawing, such as a diameter.
- Process characteristic: a process parameter that drives it, such as feed rate or furnace temperature.
- Measurement technique: the gauge, approved by an MSA.
- Sample size and frequency: for example 5 parts every hour, or 100 %.
- Control method: X-bar R chart, check sheet, error-proofing, first-off approval.
- Reaction plan: what the operator does immediately when a result is out of specification or out of control.
Frequently asked questions
›What is a control plan?
A control plan lists, for every process step, which product and process characteristics are controlled, how they are measured, how often, by which method and what happens when something is out of specification. It is a required APQP and PPAP document in the automotive industry.
›How does the control plan relate to the FMEA?
The process FMEA identifies the risks, the control plan describes the controls that keep them in check. Every high-priority failure mode in the FMEA should have a corresponding control in the control plan. Use “Create control plan draft” in the FMEA tool to start from it.
›What are special characteristics?
Characteristics that affect safety or legal compliance (critical, CC) or fit and function (significant, SC). They need tighter control, usually SPC with a capability requirement or error-proofing.
›What phases does a control plan have?
Prototype, pre-launch and production. The pre-launch control plan usually has more inspection than the production one, which is reduced once capability is proven.