What are the SPC Requirements to satisfy clause 4.20?



We are a T&E supplier, mainly for one off pieces of equipment. Any idea cocerning what SPC requirments we should be considering to satisfy the requirements of 4.19 as we do not have large runs of anyone item.



SPC vs 4.20

Element 4.20 (I think that is what you mean) is Statistical Techniques. Statistical Process Control (SPC) is just one technique. There are many other techniques that can be used to verify product or process.

We must be very careful here. Many registrars do not believe that 4.20 can be called ‘not applicable’ (I share this concept). I know some service and TE companies that end up tracking useless things just to satisfy the auditor. It would be far better for you to identify areas that should be tracked statistically. My suggestion is look for two things.

First, anything that causes you [or your customers] pain. The second thing is any time you ask things like; “Have we got any data on this?” or “How many times has this happened?”, you might be asking whether statistical tracking might be in order.

Specifically, the TE supplement also says to include R&M stuff. [And we all know your customers are free with sharing data you need to come up with OEE, MTBF and MTTR, etc. :( )

Randy Stewart

end up tracking useless things just to satisfy the auditor.

So simple, so well said and oh how TRUE. I'm not being sarcastic db it just happens way too often.

I would suggest, that if possible, visit one of your customers and study their operation. See how your product interacts with their process and see if you can identify something that is important to them in the operation. Then I would look at how my product impacts the operation and how could I improve it. Develop some ghant charts, pareto charts, etc. to see if design changes help or hinder. You will get a better feel for the MTBF and MTTR.

Here's an example. We did a study on one of our dies and noticed that somewhere around 7 hits a cable was cut (we don't have responsibility for the electrical design). The cable and electrical designers had added quick disconnects to speed up MTTR but did nothing for the MTBF. We added a cable run to our design to keep the cable from the main wear area and reduced the MTBF by 65%. We may have never heard of the issue if we had not gone out for a visit and stopped to watch the operation.
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