How Fixture Instability Created False CMM Repeatability Problems

Situation

A production inspection process was producing shifting CMM results. The first assumption was that the program or machine was the problem.

Constraint

The team needed a practical path forward without turning the issue into a larger production disruption. The exact customer, part, and program details are anonymized to protect confidentiality.

What was found

The review focused on setup repeatability, clamp force, datum contact, part loading, probe qualification, and alignment response to real part variation. The issue was treated as a measurement-system problem first, not as a part-quality conclusion.

What changed

• The problem was separated into process, program, fixture, report, and ownership risks.
• The team identified which items needed correction before more production pressure was added.
• The next step was tied to inspection readiness instead of a vague request for CMM help.

Result

The customer had a clearer inspection path, fewer unresolved questions, and a more practical way to decide whether the issue required programming, troubleshooting, training, or workflow support.