# Help interpreting MIL-STD-105E Single Sampling Plans Tables

#### Mark Meer

Trusted Information Resource
Hi All,

I'm needing some help interpreting some of the tables in the MIL-STD-105 (E) standard. In particular the Single Sampling Plans tables (Table II).

My confusion is this: how/why is it that the AQLs are specified up to 1000?

Aren't AQLs expressed as percentages? In practice, is there any reason to even consider the columns of AQL >= 100?

Also...
I know that MIL-STD-105E has been superceded by ANSI/ASQC Z1.4, but as I understand, they are still quite similar. So for anyone (like me) just wanting to explore acceptance sampling without having to buy the ANSI/ASQC standard, the MIL-STD-105E can still be a good starting point.
Can anyone familiar with the differences between the two please confirm?

#### WCHorn

##### Rubber, Too Glamorous?
Trusted Information Resource
Re: Help interpreting MIL-STD-105E tables

There is the potential for defects per piece inspected, so the higher AQLs are for that purpose.

Z1.4 and 105E yield the same sample sizes and accept/reject numbers. There may be some subtle differences but I don't think those differences affect the accept/reject decision.

#### Mark Meer

Trusted Information Resource
Re: Help interpreting MIL-STD-105E tables

Thanks for the prompt reply WCHorn.
...but I'm afraid my statistically-challenged brain is still confused.

I've seen some industry guidances, and SOPs from other companies, specifying a default AQL of 1.0. This makes sense to me: we want confidence that the percent defects in any given accepted lot are never above 1%.
But an AQL of 65-100, let alone 101-1000? Doesn't make sense...

Also, the acceptance and rejection numbers for AQL >= 65 are larger than the total sample sizes. This too, I find very confusing...

In the definition note for AQL, the standard states:
"...the AQL is a designated value of the percent defective...for which lots will be accepted most of the time..."

So, doesn't this mean that selecting an AQL of 100 would allow lot acceptance even if 100% of the samples were found defective? (which clearly makes no sense... ).

Can you possibly give (or reference) a simple example in which these higher AQLs might be useful?

#### WCHorn

##### Rubber, Too Glamorous?
Trusted Information Resource
Re: Help interpreting MIL-STD-105E tables

This makes sense to me: we want confidence that the percent defects in any given accepted lot are never above 1%.
Starting here, you are actually assuring that the average percent lot defective of a series of lots is 1 percent or less (assuming you're using the normal/tightened/reduced switching procedures). If you want to limit the percent lot defective in a single lot, the standard gives limiting quality (LQ) plans for that purpose.

Can you possibly give (or reference) a simple example in which these higher AQLs might be useful?
If you're making something that has the possibility of several defects per unit (an automotive fender with paint defects, for example, where there is a limit of, say, 5 per unit), then you could use an AQL of 250 (250 defects per hundred units). That would mean the average defects per unit would be 2.5 or less, again using the switching procedures.

If a single defect on a unit makes the unit a defect, then you're perception is correct; it doesn't make sense. If there are some number of defects per unit allowed before the unit is declared defective, then the larger numbers make sense. I'm sure other's on the Cove may be able to give you better examples. I made this one up.

#### David-D

##### Involved In Discussions
It goes back to the earlier poster's comments about counting defects, rather than defective units. For example you'd count how many total scratches you had on your sample of 3 doors.

For the example of a sample size of 3 (code B) with an AQL of 1000%, you would inspect three items and if there were 44 or less defects (scratches, gouges, etc) on all 3 of the sample doors in total. If there are 45 or more defects, the lot would be rejected.

As it is a 1000% AQL, if the supplier was running at 10 defects per item, them they would consistently have the product accepted.

Hope that helps.

David

#### Mark Meer

Trusted Information Resource
Ah-ha! Thanks! The numbers make sense now.

Obviously I was (mistakenly) assuming that each unit was either declared defective or not (pass/fail type inspection).
...I had not considered the possibility of multiple defects per unit...

That being said, it's hard to imagine ever considering 30 defects in 2 samples (Sample code A, AQL=1000) to be acceptable. I guess if said defects were really minor...

In anycase, at least I understand the numbers now... thanks again!

...now, on with the rest of the standard....

Help interpreting 21 CFR Part 806 (corrections and removals) Other US Medical Device Regulations 1
M Biocompatibility in Respiratory Products - Help interpreting whitepaper IEC 60601 - Medical Electrical Equipment Safety Standards Series 22
B Help with interpreting stock market terminologies Coffee Break and Water Cooler Discussions 4
S Interpreting Level of Confidence - Round Robin for Tensile Testing - Help needed Statistical Analysis Tools, Techniques and SPC 4
N TL 9000 - Help Interpreting Normalization Unit for Measurements TL 9000 Telecommunications Standard and QuEST 2
L Software and Web Site Development - Need help with interpreting 7.5.2 ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 5
P Help Interpreting "Variable Tolerance Limit" - MMC Modifiers - Geometric Tolerance Statistical Analysis Tools, Techniques and SPC 18
ISO/ IEC 17021 Resource requirement (need help) Document Control Systems, Procedures, Forms and Templates 5
Supplier Quality level category help - high level ISO 13485:2016 - Medical Device Quality Management Systems 6
Amendment Class II - Please confirm if the submission is by email (Canada) - Help Canada Medical Device Regulations 0
ISO/IEC 17065 certification scheme Help Other ISO and International Standards and European Regulations 7
Help to Suggest name for a new certification and inspection company Coffee Break and Water Cooler Discussions 7
AS9100 new certificate, but need QMS software, help Quality Assurance and Compliance Software Tools and Solutions 2
Manufacturing Process Audit Help IATF 16949 - Automotive Quality Systems Standard 6
Case study help as per ISO 9001: 2015 ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 17
Case study solution help required as per ISO 9001 : 2015 ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 1
Beginners help with ISO3951-2 Combined control s-method n>5 what is Phi ?? Inspection, Prints (Drawings), Testing, Sampling and Related Topics 0
Medical Device Software - Is a Help Button required? IEC 62304 - Medical Device Software Life Cycle Processes 1
Need help with analysing a survey on minitab Using Minitab Software 1
Help me improve the definition for internal PPM Manufacturing and Related Processes 3
Help: QFD House of Quality Quality Tools, Improvement and Analysis 1
New to Site - Request Help with API Q2 Implementation Oil and Gas Industry Standards and Regulations 10
Please, help with document on ISO/ TS 17758 and (IDF 87: 1979). Thank you. Manufacturing and Related Processes 1
Class medical device (MDD) - Classification help EU Medical Device Regulations 1
A proposal for the model Quality Management - I need help for the project ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
Help with Drawing Review - ISO 9001:2015 ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 6
% Study variation low, % tolerance high - GR&R Interpretation help Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
Probability - Need a help to solve the below question Statistical Analysis Tools, Techniques and SPC 5
Thanks for the help Coffee Break and Water Cooler Discussions 0
Can any one help me with an urgent BIOCOMPATIBILITY Impact assessment? Internal Auditing 9
Help establishing regulatory requirements - Plastic dental cartridge syringe US Food and Drug Administration (FDA) 0
Medical Device Contract Manufacturing Requirements and Information - Help wanted ISO 13485:2016 - Medical Device Quality Management Systems 5
Need Help - Runout - Function Gage Inspection, Prints (Drawings), Testing, Sampling and Related Topics 7
Burn out - Tips to help combat QC burnout Career and Occupation Discussions 9
Measurement system analysis - Can you help me about implementation MSA for CMM device Manufacturing and Related Processes 2
New to FAIR, need help in filling it out AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 8
Informational From RAPS: Danish Regulators Seek to Help Smaller Companies With EU MDR Compliance Medical Device and FDA Regulations and Standards News 0
Reliability Testing - Weibull Analysis Help Reliability Analysis - Predictions, Testing and Standards 4
Help me to decide which test to use - If each proportion belongs to the same population Using Minitab Software 7
Informational US FDA issued the first warning letter for UDI violations to help ensure compliance Medical Device and FDA Regulations and Standards News 0
QMS Template Help - Small machine shop/job shop Manufacturing and Related Processes 1
Pls help --- Need expert advice on Video Measurement Measurement Uncertainty (MU) 0