Part Inspection

Thanks in advance. Sorry if this is in the wrong area. I started in a new shop last week. There is no inspector. I set up a twin spindle twin turret my first day and ran an 800 piece order over the next two shifts. They were all sent back today.

I did a full inspection of my first ten parts and gave turn over. I directly looked at each person I gave turn over to, went thru the part, tool lists and set up sheets. I asked them if they had any questions and they said no. I admit I did not document anything. When I asked about inspection sheets I was told by the owner “ we don’t have those”.

So I will now make my own. I am happy with the sheets. My main question is how do you all set the quantities to be inspected? For example a certain feature is 1 every 10 or once an hour.

Thanks so much.

"They came back"

I'm assuming your company has at least some QC in place then? If so, what is your accepted quality level (AQL)? What do your customers demand?

Sorry for all the questions. Just trying to gain a better perspective of your quality requirements.

Chuck

Thanks. It seems that everyone is on their own to check parts. After set up I called another guy over and had him go hru my "first article". After this, I do plan on haveing another paper print with each dim clearly noted on a inspection sheet. I understand that anything can be pencil whipped. I have never had to issue inspection paperwork. So I have no idea where to start with inspection frequency. Any input is awesome.

Hello,
I don't do machining but for precision sheetmetal work it is common to check at least 10% of the work after the 1st article passes QC. If you use a percentage it should be easy to implement and figure the sample rate for any quantity. For larger quantities after several good inspections during a run the percentage can be increased so there is less time lost doing inspections. I hope some of this may be relevant.

Make friends with someone in a shop's Quality department. They've probably developed some values you can use for a good statistical sampling method. Some dimensions you might get away with measuring once per shift. Others, like a ±.0002" tolerance, you probably should check 100%. Let us know what you come up with.

Full inspection every 1 in 10 parts seems to be the norm. Tight tolerance work perhaps a little more frequently - or at least the dim. with tight tolerance.

Thanks all. I guess monday we start sorting. I like the full inspection 1 in 10. Thanks again,

Have someone else double check them as a comformation check for another set of eyes on the same part.

I believe the old milspec program had a sampling plan that had schedules adjusted for tolerances.

Befor the ISO programs that was what most big companies based their QC programs on.

Dick Z

If you can keep the parts sorted in some way so that you know the order in which they were made. If you do a spot check and find a problem, you can then check the previous parts until you find when the problem occurred. I work in a large tool & die shop where everyone has to verify the dimensions they sized on the print. They are then held accountable with scrap reports, withheld bonuses, pay raises... etc etc. Ultimately, scrap needs to be stopped at the machine, not in an inspection department on the day the job is supposed to ship, and certainly not in the customers hands.

Mil-std-105 has a sampling plan that has the same sample size per lot ISO 9001:2008, and possibly others ( i only know 9001 and as9100)

You can download mil-std-105 at assistdoc.com, open rev E, the largest of the file sizes

Page 18 and 19 have the sample code letters and the lot size acceptance/reject sizes, they work very well for sampling enough to catch mistakes

-Jacob

We create in process SPC inspection charts for the operators at our shop. We use an AQL Inspectors Ruler like this http://www.aqlinspectorsrule.com/details.html . Our form is a generic excel spread sheet and we number all dimensions on a print to correspond to the inspection characteristic to be checked. So number one on the sheet would read C3 .120 +/- .03 with a sampling rate to fit the tolerance of the dimension and batch size and the dimension on the print for the feature in zone C3 would be numbered 1 to match.