The "hidden pitfalls" in the TS audit of an automotive interior factory: How exactly should the MSA of electronic scales be understood?
I got to know a friend who works in the automotive interior parts business some time ago. His company is currently in a war of attrition in the TS16949 system audit — they didn't pass the two rounds of preliminary audits completely, and there are always some unexplainable issues lingering. When we were chatting yesterday, he rubbed his temples and said, I have to go for the re - audit tomorrow. This is already the third time. If we still don't pass, the production line will have to stop
I asked, "Why hasn't the review been finalized after so many rounds? What's not been done properly?"
He slapped the table and said, "It's not that we didn't do well! It's that the auditor dug an 'invisible pit'!" Then he restored the details of the previous round of review:
The auditor first asked, "Have you conducted the MSA for the key measuring equipment?" Immediately, they brought out a whole set of materials - from the repeatability and reproducibility (R&R) report of the coordinate measuring machine to the bias analysis of the vernier caliper. Each page was marked with "Measuring tools corresponding to key characteristics". After flipping through the materials, the auditor said, "It's quite standardized." But then, suddenly changing the topic, the auditor asked, "Why haven't you conducted the MSA for the electronic scale that is used every day in the workshop?"
"We were all stunned at that time. The electronic scale is used to weigh injection-molded parts. What problems could it possibly have? A colleague casually replied 'Oh', and as a result, he was marked with a 'serious non-conformance' on the spot." The angrier he got as he talked, "I've been in the quality field for eight years and have never heard that MSA needs to be done on electronic scales! Isn't MSA targeted at product characteristics? What 'characteristics' of the electronic scale itself need to be analyzed? Could it be that when my colleague and I weigh the same part, the numerical values can differ by 0.5 grams?"
His confusion actually hits the "MSA cognitive blind spot" of many quality professionals
Many people's understanding of MSA stays at "analysis of complex equipment". For example, only high-precision instruments such as coordinate measuring machines and spectrometers need to conduct R&R, linearity, and stability verification. However, the "measurement system" in the TS16949 system is defined as "the collection of all elements involved in measurement". No matter how simple the tool is, as long as it is used to determine the "key characteristics" of products/processes, the "reliability of measurement results" needs to be verified.
For example, consider the electronic scale in a friend's workshop. Suppose it is used to measure the "injection molding weight of interior parts" (this characteristic directly affects the assembly tolerance). Then the "weighing accuracy" of the electronic scale (for example, when weighing a 100-gram standard weight, whether the display shows 100 grams), "repeatability" (how much the values fluctuate when the same person measures the same part 5 times), and "reproducibility" (how much the results differ when different people measure the same part) directly determine whether the conclusion of "qualified weight" is credible. If the electronic scale itself is inaccurate, even if the workers operate in a very standardized way, the "qualified parts" measured may have already exceeded the tolerance - this is the core problem that MSA aims to solve: to prevent "measurement errors" from masking "product problems".
More importantly, the problem with the friend is not only that "the MSA of the electronic scale was not carried out", but also that they didn't understand "the flexibility of MSA" -
TS16949 does not require that "complex R&R should be done for all measuring tools", but requires that "based on risk assessment": if the accuracy of the measuring tool is much higher than the characteristic tolerance (for example, the accuracy of the electronic scale is 0.1 gram, while the weight tolerance is ±1 gram), and the daily calibration can ensure stability (for example, calibrating with standard weights every month, with an error ≤0.05 gram), then the MSA of the electronic scale can be simplified to "calibration record + tolerance matching analysis" instead of having to do a full R&R. However, there is an essential difference between "doing it in a simplified way" and "not doing it" - the problem with the friend's team is that they default to "the electronic scale does not need to do MSA" rather than "doing MSA in a more reasonable way".
The auditor's "sudden question" is actually to verify "whether you really understand the logic of MSA". If the friend could have asked a rhetorical question at that time, "Our electronic scale has an accuracy of 0.1 grams, the weight tolerance is ±1 gram, and the daily calibration error is ≤0.05 grams. Is it necessary to conduct a complete R&R?", perhaps the "non - compliance" would not have been established. Because the essence of MSA is "to control measurement risks" rather than "mechanically execute the process".
Finally, the friend sighed and said, "Now I understand. It's not that the auditors are 'cunning'. It's that we ourselves have turned MSA into a 'formality'. We only know that 'it should be done' but don't understand 'why it should be done'."
In this conversation, the so - called "feeling wronged" is essentially the passivity caused by "the misunderstanding of the essence of tools".
When many enterprises conduct MSA, they only focus on the "mandatory items" in the "audit checklist" (such as complex equipment), but ignore the "risks outside the checklist" (such as basic tools). They think that "MSA doesn't need to be done for electronic scales" because they haven't figured out that MSA is not about "torturing tools" but about "protecting product quality" - as long as a tool is involved in the "measurement of key characteristics", it is necessary to confirm that it "won't mislead judgments".
Back to the question itself: Should an electronic scale undergo MSA?
The answer is "Consider its use" - if it is used to measure "critical characteristics" (such as weight and dimensions that affect product functionality), it needs to be done; if it is only used to measure "non - critical characteristics" (such as rough weighing of raw materials), it can be simplified or exempted. However, the prerequisite for "whether to do it or not" is that you can clearly explain "why" - rather than saying "I've never heard of it".
A friend's experience serves as a wake - up call for all quality professionals: The "traps" in system audits are never set by auditors, but rather result from our own superficial understanding of standards. When you truly understand that "MSA is to ensure reliable measurement" rather than "to pass the audit", you won't panic when facing issues like "electronic scales". This is because you can explain clearly "why to do it" or "why not to do it" from the perspective of "risk".
Finally, my friend said, "I have to quickly complete the MSA analysis of the electronic scale tonight. Even if it's a simplified version, I still need to let the auditor see that 'we understand'."
Perhaps this is the meaning of review: not to "find faults" but to help you discover "unrecognized risks".