By Walker Woodworth, President of Frank Roth Co.
We regularly encounter a measurement misalignment between a customer’s inspection system and our own. Too often, suppliers of complex machined parts treat prints and specifications as all-inclusive. However, it’s critical to also consider the customer’s inspection methodology and understand critical quality characteristics, especially the 100% must fit dimensions.
Without that information, latent program risk increases, driving avoidable Cost of Quality (CoQ). False non-conformances, invalid capability metrics, and misdirected corrective actions become inevitable. Fortunately, suppliers can avoid these issues, stabilize quality performance, and improve customer satisfaction by using the low-cost risk-reduction action of aligning measurement methodology.
The Core Issue
In precision manufacturing, observed variation is not purely process driven. It is the combined effect of:
- Actual process variation
- Measurement system variation
When supplier and customer measurement systems differ (datum interpretation, CMM measurement techniques, fixturing, other measurement systems variance), a portion of reported nonconformance is measurement noise, not true process behavior.
This leads to:
- False rejects and acceptance disputes
- Increased scrap, rework, and program risk
More frequently than you may imagine, customers’ inspection methodologies have significant measurement system variation.
Why It Matters
When measurement systems are not aligned:
- Capability metrics lose credibility.
- Corrective actions target symptoms instead of root causes.
- Quality costs increase without improving product performance.
- Manufacturing operations teams lose confidence in the data.
In short, decisions are made on statistically compromised information, and they can have a huge impact on your manufacturing organization and customer satisfaction.
How to Manage Risks and Costs
Process capability and measurement approaches are tools that help prevent the pitfalls that stand in the way of optimal performance, quality, and cost-efficiency. Here are some techniques for getting the vital information you need from your customers.
1. Talk to your customer and frame your request around acceptance risk.
Do not ask for their method “to understand it.” Ask to prevent false nonconformances.
Some effective ways to frame your request include:
- “We want to ensure first-pass acceptance and avoid inspection interpretation risk.”
- “Multiple GD&T-compliant measurement approaches can yield different results; alignment avoids false rejects.”
Phrasing your ask in these ways makes the request about protecting their program and improving your process, which are both in their best interest.
2. Tie measurement technique to the drawing, not preference.
Customers resist “make work” requests. Be specific, standards-based, and explain why your request is critical to quality.
Ask for:
- Datum structure application and precedence
- Functional gaging vs. variable measurement
- Measurement equipment type (CMM, optical, different gages, etc.)
3. Ask for a gage measurement study.
You should know your own process variance—and you need to understand your customer’s inspection variance. Insist on and lead a measurement system study that involves you and your customer measuring the same parts. This can be quite revealing for both parties.
Recognize that all of this does not change drawing requirements or transfer acceptance authority. It ensures both parties are observing the process through the same lens.
The Bottom Line
Measurement alignment shifts spend from failure and appraisal to prevention, where ROI is highest. Organizations that align measurement methods typically experience:
- Fewer false nonconformances
- Reduced containment and investigation costs
- Improved customer confidence and audit outcomes
Prioritizing measurement alignment between inspection systems lays a successful foundation for controlling costs, ensuring quality, and retaining customers. If these are important to your company, contact us to learn more about how our careful alignment assessment process can help you achieve exceptional manufacturing results.
