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7.1.5.1.1 MSA for built-in measurement systems

Discussion in 'IATF 16949:2016 - Automotive Quality Systems' started by Volker, Aug 28, 2018.

  1. Volker

    Volker New Member

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    Hello everyone,

    I'm currently confused with this clause regarding equipments that have built-in measurement systems to control their operation.
    A simple example would be an oven that has a built-in temperature as well as a time control. Let these process parameters be critical for product quality and assume there is an entry in the FMEA that if the temperature and time would be wrong, the product is malfunctioning. Consequently, there would have to be an entry in the control plan. As temperature and time are measured by the oven, a MSA would be required according to 7.1.5.1.1.
    To be honest, this seems to be exaggerated to me, as the equipment was designed and is specified to be able to fulfil the process requirements.

    How do you handle such equipments and potentially required MSAs?

    Thanks in advance,
    Volker
     
  2. ncwalker

    ncwalker Well-Known Member

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    We say that every gage can have a gage R&R performed on it. This is a true statement, as gage R&R is just a statistical model of the gage system.

    I've seen custom inline gages that were (like your oven) designed by a company to make a particular measurement turn around and fail a gage R&R study. Much to the detriment of the person who bought the device. But ... it was a custom device AND it was measuring an actual part.

    It's not like there aren't ovens everywhere, and, we understand how to measure both time and temperature.

    The problem (as always) is our customers and auditors and how THEY interpret the thing. So any advice I give, may or may not work.

    If it were me, and the oven temp was process critical, I'd want it confirmed. In fact, I would have put this in the contract when I bought it (or rebuilt it). But that said, you could simply do this with a second calibrated thermometer of some sort. The controller isn't measuring a "part", it's measuring an environment. So ... if you heated it up, and checked a few times on a secondary device that 200 C was 200 C and 400 C was 400 C, etc (I'd do 5 points). That would ensure it's calibrated. Which is what you're really after.
     
  3. Serious Man

    Serious Man Active Member

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    Shortly. Performing MSA for every control system mentioned in control plan is required.
    Using methods described by AIAG MSA book for every control system mentioned in control plan is not required.

    Reason are various variation sources of control systems.
    Sometimes it is human, hardware and software, sometimes it is hardware and software, sometimes hardware only.

    Equipment calibration is one of methods used to analyse control system variation and sometimes it could be the only one applicable.
    Start from determining variation source(s) and then select statistical method appropriate to evaluate variation size.

    Oven temperature control system has two sub-systems - measurement and regulation.
    For measurement, we have to confirm that thermocouple gives reliable results, so it is mainly hardware.
    For regulation, we have to confirm that based on defined inputs we get expected outputs, so it is mainly software. I am not talking about heaters itself.
    Separate calibration of these two sub-systems would be enough.
    It is briefly explanation, how I see it.
     
  4. judegu

    judegu Active Member

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    @ Serious Man
    Sir! When I read your post, I got a little confused.
    As the subclause 7.1.5.1.1 Measurement system analysis states, "The analytical methods and acceptance criteria used shall conform to those in reference manuals on measurement system analysis. Other analytical methods and acceptance criteria may be used if approved by the customer."
    So if we perform the MSA on the build-in temperature sensors and times, not using the methods in the manual, we NEED a "YSE" from the customers. Is it practical to ask the permission from customers? Or is it necessary to do that? Never heard of doing MSA on temperature sensor and timer. :confused:

    And in my factory, Oven also plays a very important role. If something is wrong with the time and temperature, the silicone curing will be a mess which will definitely post a great impact onto the downstreaming processes (make the semi-product hard to process) and on the conformity of the final products.(at least won`t meet the appearance criteria).

    However we didn`t put the build-in temperature sensor and timer of oven into the control plan. Instead we put the setting temperature and the corresponding time (another words, the process specification) into CP. So we don`t need to do the MSA of the build-in temperature sensor and timer.

    Regarding MSA, there are five aspects. Stability, Linearity, Bias, Repeatability, Reproducibility. How to evaluate temperature and time of each oven in terms of these five aspects? It is quite hard to do the MSA on these intangible objects.
     
  5. Golfman25

    Golfman25 Well-Known Member

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    Not only that, but many customers may specifically reference the AIAG books in their customer specific requirements. So you need to be careful with any absolutes.

    As for doing the MSAs good luck. It's a never ending battle.
     
  6. Serious Man

    Serious Man Active Member

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    My response was focused on initial post and questioning reliability of oven built-in temperature control system.
    I've referred to first sentence of clause where key words are "variation in results".
    Measurement variation has various sources and MSA manual (e.g AIAG), if I am right, is focused on cases where measuring person partially affects it.
    Oven built-in temperature control system is not this kind of measurement system, but as there is still variation in it, it shall be studied.
    In my opinion calibration give us all what we need to know in this case.

    Crucial question is "Does a machine built-in process characteristic control system is "inspection, measurement and test equipment system" as specified by this clause?"
    Maybe not, so we overinterpret requirement?

    What I am 100% sure is, that built-in systems shall be in control plan.
    Setup and its verification is one thing, but later there is only built-in control, which assures that process specifications are met.
     
  7. judegu

    judegu Active Member

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    Regarding the Heating Device, in this case which is the oven, the temperature and time are key management points. Based on the terminology introduced by the APQP manual, they are the process characteristics. They definitely needs to be included in the CP, serving as kind of process specification. And who makes sure the temperature and time is right? Yes, it is the built-in temperture and time control system and which are built in the oven. So I think it is safe to say the oven itself makes sure the right tempearture and time. So we don`t need to emphasize built-in control system in the CP. As a result, we don`t need to have the headache about how to do the MSAs on this built-in system. What we need to do is just the regular calibration or verification and do the right parameter setting.

    And there is another example I want to add here. In my factory, we use die bonders to attach the LED dies onto the substrate with adhesive (LED packaging industry). In order to firmly attach the dies onto the substrate, we need to press the die a little bit when the machine is attaching the die onto the substrate. However we need to control the force of this "press". Too much the die will be damaged, too little the die will fall off the substrate. And what we do is setting the right parameter of the "Press" force in the die bonder to ensure the right force being used. And this force is also controled by a built-in force meter in the machine which is quite simiar to the built-in temperature control system we are talking about.

    So my point is, maybe, in term of the scope of MSA, we needn`t put much attention in the built-in measuring system of the manufacturing machine, they are just part of some value-added machine (Manufacturing equipment). The regulare calibration/verification will do a good job to take care of them.

    What is your opinion about this? ;)
     
  8. Volker

    Volker New Member

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    Hi guys,

    thanks for all of your valuable contributions.

    My thinking on this was (and which was at least partly confirmed by your posts) :
    - Built-in controls are by design capable
    - It needs to be verified that the equipments specifications match to the process requirements
    - Upon installation, the equipment's functionality according to the specifications has to be verified
    - After that the correct function is guaranteed by (preventive) maintenance
    - Within the maintenance, the built-in controls (as far as possible) are calibrated / verified
    - The measurement system used for maintenace should (shall) have a MSA

    Consequently, in the control plan, the equipment would be the oven, process characteristics would be temperature and time but the measurement system would be that one used in the maintenance. I thought about an additional comment in the CP such as "This equipment has built-in controls (w/o operator influence) and is capable to fulfil the process requirements according to its specifications. The correct operation and meeting of equipment specifications is verified by preventive maintenance. No MSA is done for the built-in controls.".

    This should save me from headaches to report it in the PSW.
     
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  9. judegu

    judegu Active Member

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    @ Volker
    A nice post!
    And I don`t think "The measurement system used for maintenace should (shall) have a MSA" is necessary. I still can`t figure it out a proper way to do the MSAs on Temperature and Time. Maybe as long as the maintenance device is treaceable, it will be ok.
    And regarding the additional comment in the CP you mentioned, based on the principle “No ask, No explanation”, maybe we should not make this additional comment. If during the second-party & third-party audit(s), the auditor doesn`t bring this up, we are good. Right?
    Personnally, due to the position of our products in the supplier chain, we don`t have auditors from the OEMs, only a few from Tier 1 suppliers [lamp Assembly].
    The auditors didn't bring up this built-in measurement system issue. Let alone the 3rd-party auditors.
     

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