Measurement, MSA, and SPC
Measurement system analysis and statistical process control turn measurement into evidence. Without them, every dimensional result is just an opinion. With them, the PPAP submission, the control plan, and the day to day decisions on the line all rest on numbers you can defend. The guides in this topic cover Gauge R and R acceptance criteria, the difference between Cpk and Ppk and when each one applies, and how a control plan ties measurement frequency to process capability. Useful for the engineer setting up a new study and for the team trying to interpret last week is data without restarting the argument from scratch.
5 articles in this topic
Featured article
Cpk vs Ppk: Which Process Capability Index to Use for PPAP
Cpk and Ppk measure process capability differently and are not interchangeable on a PPAP submission. Here is what each one measures, which sigma each uses, and what PPAP Element 11 actually requires.
Read the full guideGauge R and R
Setup, acceptance criteria, and how MSA results feed PPAP.
How to Run a Gauge R&R Study (and Why a Passing %GRR Can Still Fail the Part)
A Gauge R&R study can clear the 10% line and still be worthless, because the number is being read against the wrong denominator. A worked study, run through QualityEngineer.ai's own Analyze module, showing what %GRR against tolerance hides, why NDC catches it, and how Element 8 coverage finds the gauge nobody studied at all.
Gauge R&R Acceptance Criteria: %GRR, NDC, and What AIAG MSA Requires
A Gauge R&R study passes when %GRR is under 10% and NDC is at least 5. Between 10% and 30% is conditional. This guide covers the AIAG MSA thresholds, what %GRR and NDC mean, which values trigger rejection, and what to do when a measurement system does not pass.
Control Plan
Translating capability and MSA into a control plan that survives audits.
Western Electric Rules: What a Control Chart Catches Before a Point Breaches the Limit
Western Electric rules flag drift and trend patterns on a control chart before any point crosses 3-sigma. Here is what each of the 8 rules checks, which ones run by default, and what actually happens when one fires.
Control Plan in Manufacturing: What Goes in It and How to Build One
A column-by-column breakdown of the manufacturing control plan: what each field requires, how it connects to your PFMEA, and what auditors actually check under IATF 16949 Clause 8.5.1.
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