Changing Inspection Frequency on the Control Plan

[Stuart Andrews]

During a recent surveillance audit, our auditor gave us a minor nonconformance because I stated on our control plan that we performed an "hourly" SPC check for certain dimensions. Unfortunately, because of work load and only having 1 SPC measuring station and five machines, the SPC checks were being done slightly over 1 hour. This meant that eventually one hourly check may be missed eg 6 hourly checks performed in 7 hours.

Now I don't want to change the wording on the control plan because I'll have to notify my customers of a change in inspection frequency. So where do I stand on this issue.

Any thoughts peeps!?!

[M Greenaway]

You could define in your quality manual that an 'hour' is a period of duration of 120 minutes ! tee hee

Seriously you can either get the necessary resource to fulfill your intent for hourly SPC checks, or try to redefine your time period. COuld you get away with saying it means an hour of production time and not an hour of real time ?

[Stuart Andrews]

At the moment we don't have the funding to cover the resource issue. But sometimes we'll meet the hour frequency and sometimes we won't eg if the operator is busy changing over a machine.

At what point does an hourly check not become an hourly check. If we did a check at 1 hour 5 mins I would imagine that would be acceptable. What about 1h 10m? Or 1 h 20m?

Any further thoughts?

[M Greenaway]

Could the machines stop after one hours production to await the SPC checks ?

Just thinking your hourly check could mean 'an hours worth of production' and you wont produce any more until the SPC is done.

[Stuart Andrews]

I wouldn't really want to stop the machines, it isn't critical that the checks are performed on the dot. What do other people do when their SPC checks aren't carried out in the allotted time? I can't imagine people would stop their production unless it was critical for them to do so.

FYI It isn't critical, as such, because we manufacture such high volumes and the process is so stable. The checks would be performed every hour if we didn't have a resource issue.

[M Greenaway]

Stuart

If it isnt critical, and the process is very stable why not wind out the frequency of checks, or do away with them altogether ?

Our SPC is done on production count, and is therefore not time dependant - could you change yours to being based on production count ?

[D.Scott]

I am with Martin. If the check isn't critical and the process is so stable, cut back on the number of checks. It seems to me you are getting "busted" on the 1 hour issue rather than on not controling the process. We have a similar issue although we have not had a nonconformance because of it yet.

If you want to keep the hourly check, you will need to do as we have to - add the word "approximately". If you define the inspection frequency in your procedure as "although not critical nor mandatory, inspections should be done approximately every hour" - you have not changed the inspection interval so you won't need to notify the customer of a change in the CP. If the auditor questions the interval, you can show him the procedure defining the acceptable interval deviation.

Dave

[Marc]

As an extreme (and to confuse the heck out of the auditor) - put a tolerance on your time. +/- 15 minutes or something. I'm assuming this is a QS-9000 or TS 16949 audit.

I suspect very few people (reality here) checks a clock and does the check to the minute and second.

Anal auditor?