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Acceptance Inspection Sampling Plan Calculators 2022-08-01

Bev D

Heretical Statistician
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Bev D submitted a new resource:

Acceptance Inspection Sampling Plan Calculators - Sampling Plans

AQL, RQL. Reliability/Confidence, c=0 sampling plan calculators.

Thanks to Tim Fokkerts for the seed of this spreadsheet.

Also Known as Sam Poisson, John Heldt, Hitchcock Publishing Company (1985)
Acceptance Sampling in Quality Control, Edward G. Schilling, Dean V. Neubauer, Chapman and Hall/CRC (2009)
Reliability Statistics, Robert A. Dovich, American Society for Quality Control, 1990

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Can you walk me through on how this sampling plan works exactly? i was trying to make sense of it and I got lost.
 
Well no. Unfortunately that’s like asking for someone to walk you through surgery on yourself.

This Quality Engineering stuff is as complicated as any engineering degree program.

It is good you are here as you can learn from some very experienced and expert QEs.

It is helpful for you to ask very focused rather narrow questions at first. Also try searching for inspection sampling plan posts here.
 
Is there a specific need for a sample plan that you have?
 
It is helpful for you to ask very focused rather narrow questions at first
This.

Acceptance Inspection Sampling Plan Calculators
 
Is there a specific need for a sample plan that you have?
Yeah let me start with some context. We just had an AS9001 audit and the auditor asked if we had a sampling plan for our parts. Our shop runs CNC machines and we can manufacture anything essentially from bars no bigger than 1.5 inch diameter. The nice part about CNC machines is that they can produce high quantity of parts, and the process is the exact same for all the parts made for that specific program, but downside is that having to inspect these would take forever. So our sampling plan is based on the number of parts we make. We do have operators and leads that do in process checks, but we don't have a documented sampling plan, which appears we need. Do we just need to make the current sampling plan we have part of our QMS and that should fix it or is there something else we'd need? (I don't know if this is specific enough - my apologies, I'm still learning).
 
Who is your Customer(s)?

You may be contractually obligated to perfrom 100% inspection. Critical aerospace parts are usually 100%.
It’s been awhile since I have read that particular standard but as I remember it a statistically valid sample plan is required with justification for the sampling plan. So basically what you are doing now is probably not good enough. I’m surprised this didn’t generate a major finding.
 
Who is your Customer(s)?

You may be contractually obligated to perfrom 100% inspection. Critical aerospace parts are usually 100%.
It’s been awhile since I have read that particular standard but as I remember it a statistically valid sample plan is required with justification for the sampling plan. So basically what you are doing now is probably not good enough. I’m surprised this didn’t generate a major finding.
It's because we perform in-process inspection and validation of effectiveness comes from NCRs and CR. So it was a minor. We don't have any AS customers at the time, so that's why it's been confusing. We're primarily working with one big customer that has been dealing with the company for the past 15-20 years, and we make hundreds of thousands of parts for them weekly. For aerospace we will take much greater care, but we want to be able to have that mentality already implemented for any potential clients. Hope that answers the question.
 
What is a CR? And how does NCRs and CR ‘validate effectiveness’ of what?
Have you perfromed any gauge R&Rs?
 
What is a CR? And how does NCRs and CR ‘validate effectiveness’ of what?
Have you perfromed any gauge R&Rs?
Sorry, a CR is a Customer Return. They validate if the product is good and within tolerance essentially based on how the customer's inspection process passes. I am not aware of our company having performed any R&Rs. (This is super helpful to me btw, thank you all for responding so quickly and willing to help me understand this better)
 
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