From a thickness specification to a measurement plan

Write a complete measurement brief

Describe the stack from the surface inward: topcoat, primer, plating and substrate, as applicable. Name the target layer and state whether the requirement concerns total thickness, one layer, or remaining wall. Give both the expected interval and the tolerance in explicit units.

• Access: one side or both sides; narrow grooves or small measurement areas.
• Interaction: contact, couplant, local dissolution or cutting permitted or prohibited.
• Environment: surface temperature, movement, surface texture and accessibility.
• Output: single checks, a mapped inspection, or records that need transfer and traceability.

Compare methods against the same question

A magnetic coating measurement, an ultrasonic wall reading and a micrometer reading may all be called “thickness,” yet refer to different boundaries. Avoid comparing their numbers until the target is the same. Use the method guide to eliminate candidates that contradict the substrate, access or damage requirement.

For metal plating, XRF may also provide composition information. Its suitability still depends on the material stack and application; do not assign one universal thickness interval to every plated system.

Separate a working range from a purchasing claim

Ask whether a stated range belongs to the complete instrument family or the selected probe and material. Keep unresolved constraints visible in the comparison. “Range to be confirmed” is more useful than treating an unknown limit as unlimited.

The model finder returns candidates from known conditions. An omitted material property or an ambiguous sentence can change that shortlist. Inspect the recognized conditions and correct them before interpreting the result.

Agree on verification and acceptance

Identify reference standards, the expected check interval and what happens when a check fails. Verification against a known reference is different from changing an instrument’s adjustment. Keep the reference identity and check values with the inspection records.

Make the result reproducible

A useful report lets the next inspector repeat the setup. Include the part identifier, measurement locations, target layer, units, instrument and probe identification, operating mode, reference check and relevant surface conditions. For ultrasonic work, record the applied velocity setting as well.

• Keep individual readings; label averages and excluded readings explicitly.
• Record “no valid reading” when the required result cannot be obtained.
• Tie the final pass/fail decision to the agreed specification and decision rule.