AQL - How do I find Acceptable Quality Level?

I support Bev's suggestion, based on batch sizes and the inevitable question: "What prompts you to write down the inspection results of part 2, 10 and 12 versus, for example 3, 7 and 13? A suspicious mind would ask is there was "cherry picking" going on, even if it's unintended.

My point is, sampling is supposed to be random. That means you draw the sample, inspect it and process the results of that sample.

O.K. Folks,
I'm back...I have attached the Procedure I wrote this morning after all my searching, down loading, hair pulling, and .

I have forwarded it to a 3rd party Auditor friend who teaches auditing at Tulsa Tech, for critique. I'm sure it needs help and I was unsure about some of things, like "random" which is more like structred and "no sampling plan", which isn't true now that i think about it. But it is still in the making...thanks to all of you who helped, sent me links, and email addresses(one worked out really well Gordan).
Soooo...if anyone reads this and has some suggestions, I'm open and objective and not easily offended by criticism. I play well and like to share...Thanks,
QMSLADY

read the procedure and I don't understand why you will only record some of the measured values. Now a standard accepted practice is to record the min and the max - not random.

How will you control the random selection of 10% of the values? I also think that an auditor will find this strange, particularly with your low batch sizes.

Also the zero acceptance refence makes no sense when you are 100% inspecting. Zero acceptance refers to the need to perform 100% remediation of a lot that has 1 or more defects in it's inspection sample. Since you are already inspecting 100% of the parts, a simple statement that any rejected part falls under your procedures for handling nonconformance would be sufficient.

100% inspection is not sampling. The sampling plan's purpose is to understand risks and set out a plan to randomly pull some number out of the lot, inspect those pieces, and record results for each inspected piece.

As an auditor I would not accept the idea of inspecting 100% and writing down 10%. That is not sampling, and it would be very hard to convince me that the parts written down were randomly selected.

alspread said:

An AQL is so much calculated as it is determined. You ould pick any AQL level you wanted depending on what level of quality you want to live up to.

The AQL will determine you sample quantity to inspect from a lot. If you are performing 100% inspection, then you are not sampling and therefore don't need to have any AQL level. Just write your procedure that you do not use any sampling inspection (if that's the case).

If not (more likely) then you need to select the AQL that gives you the most assurance with the inspection resources you have available. Or (as is often the case in aerospace) your customer forces a certain minimum AQL level through their contract or specs.

You can (and will) use different AQL's for different characteristics depending on their individual signifigance, tolerance, customer designation, process capability, etc.

Good luck, and read your customer's requirements carefully on this subject and how to apply them in different manufacturing and lot situations.

Click to expand...

I attached a copy of the Procedure i wrote this morning at the end of this forum...if you want to see how I did.

Thanx...QMSLADY

Gordon Clarke said:

M'lady,
All of the replies/suggestions you have been getting are serious and express the same doubt as myself, although I do tend to be less serious than most. If I were you, I'd pick one of the "contributors" (cheapest within the USA) and give the person a phonecall. That's probably the quickest way to solve your apparent dilemma. You can then write and let the rest of us know how things progressed.

Click to expand...

I attached a copy of the Procedure i wrote this morning at the end of this forum...if you want to see how I did.

Thanx...QMSLADY

I thought I posted in this tread earlier today, but I don't see it...Well...I attached the procedure I wrote this morning...anybody have any critiques? I emailed a copy to a friend who teaches "Aditing" at Tulsa Tech. U...waiting to hear what she says ...I know it's not perfect, maybe a little rough around the edges, but I think we might be able to use this.
Thanks everyone for all your help and advice and emails...they really helped...
QMSLADY

There are several items that caught my attention:

Your procedure says that all parts will be 100% inspected, but it fails to mention how the person doing the inspection knows what characteristics will be measured. Will they also inspect 100% of all print dimensions and notes?

Your procedure says "measurements taken by the operator shall be recorded randomly up to 10% of the lot or customer requirements (which ever is less)." This means that if your customer specifies that more than 10% of the measurements will be recorded, you'll ignore their requirement and just do 10% anyway. I don't think that's what you really want it to say.

Since you're not doing sampling, why do you have the C=0 sampling table and reference MIL-STD-1916?

Also, your procedure References AS9100-2008. It should be either 2004 or 2009. There is no 2008 version.

I hope this helps...

Bev D said:

read the procedure and I don't understand why you will only record some of the measured values. Now a standard accepted practice is to record the min and the max - not random.

How will you control the random selection of 10% of the values? I also think that an auditor will find this strange, particularly with your low batch sizes.

Also the zero acceptance refence makes no sense when you are 100% inspecting. Zero acceptance refers to the need to perform 100% remediation of a lot that has 1 or more defects in it's inspection sample. Since you are already inspecting 100% of the parts, a simple statement that any rejected part falls under your procedures for handling nonconformance would be sufficient.

Click to expand...

Bev,

I see what you mean...as I said, this is a rough draft...but all week end the wording has been bugging me...I think you narrowed it down for me... thanx qmslady

qmslady said:

Bev,

I see what you mean...as I said, this is a rough draft...but all week end the wording has been bugging me...I think you narrowed it down for me... thanx qmslady

Click to expand...

OK to the "rough draft" as there are quite a few spelling and grammatical mistakes. I'm also left wondering who it is actually written for? One of the things that impressed me most on visits to the USA was how simply instructions and procedures were often written - especially due to the population mix you have. I don't feel this is the case here - unless everyone employed by your company has no problem with the English language. KISS comes to mind

I was also under the impression that your batches were in relatively small number so why the inclusion of "vast qualtities" in the sampling plan? As you apparently don't accept defects then why have a sampling plan anyway? It can't take long to find out what dimensions and characteristics to be on the look-out for. SPS when possible on the machines would pay off quickly. The SPC can also be used to monitor the machinists. A person that never makes a mistake doesn't do anything - but there are always one or two that think they have to make mistakes frequently to show the world how much they do do