What is AQL, Inspection Level, and Type of Inspection

T

tahashamim

#11
Is the following statement true?

"Operating Chracteristics Curves use to be included in the full text of the old Mil 105 standard. These should help you answer your question.
Be very careful however, that you don't use too sharp a pencil when dealing with these issues.

The Dodge Romig sampling schemes (from which the standard was derived) are very dependent on several statistical assumptions. Some of these are:

1)Purely random sample selection.
2)Statistical stability of the stream of product being presented for sampling.
3)A continuous, homogeneous, stream of product from one source.
etc., etc. etc.

If any of these conditions cannot be verified, you need to investigate a different approach.

Shewhart told us that only in cases of statistical stability, could the results of sample nspections be extrapolated to those products that weren't inspected or tested. Sampling plans are no different. "


Does anyone out there has the full list of the assumpions behind MIL STD?

Since we are Contract Manufacturing for electronic assemblies, we have lots of manual assembly and many different products. We have different PCB designs with different people placing different components; so much variation!

Will MIL STD plan even work in our set up?

Thanks,
Taha.
 
Elsmar Forum Sponsor
B

Benjamin28

#14
http://www.itl.nist.gov/div898/handbook/ppc/section3/ppc33.htm

Taha I'm going to direct you to this website as it offers very practical information and I enjoy the structure of the site, you can easily follow the steps and click on links for further elaboration. I'm not really aware of specific books myself, what I've learned has been out of multiple books, examples, standards and other media specific to engineering and sampling.

Like I said, sampling plans can get confusing to a new user and moreso when putting them into initial use on a product.

I'd like to understand what your goal is? You want to reduce final inspection on all boards you produce from 100% to sampling, but the products are coming from different processes and are subject to different inspection items?

I wouldn't try to implement the same inspection plan to different products, I would have an inspection plan for each product, each process. This way if one process goes out of control I won't be rejecting lots from the other processes and increasing my inspection back to normal for no need.

Your list of conditions is true yes, sampling plans are based on statistically controlled processes, uniformity of sample size, lot size, product homogeneity. I would suggest getting your hands on a copy of ANSI Z1.4 as this replaced the MIL STD you reference. But your statement is true yes, you can not hope to extrapolate correct data from a sampling plan unless you meet those conditions, primarily because there would be too much variation in the process to begin with. It would be like trying to count how many stars are in the sky by counting a horizontal number and vertical number grid and multiplying, only the stars aren't in a uniform position so the number would not be correct.
 
Thread starter Similar threads Forum Replies Date
N Visible particles inspection in powders for injections. Approaches to AQL level Pharmaceuticals (21 CFR Part 210, 21 CFR Part 211 and related Regulations) 1
Q AQL - How do I determine Acceptable Quality Level (AQL) for In-Process Inspection? AQL - Acceptable Quality Level 2
B Choosing Inspection Level and AQL AQL - Acceptable Quality Level 1
M AQL and the impact of increasing Batch Size, or changing Inspection Level AQL - Acceptable Quality Level 2
H Need help with AQL (Acceptable Quality Level) for a QC inspection AQL - Acceptable Quality Level 8
N AQL - Sampling plan (variable, inspection level ii, normal inspection S-method) AQL - Acceptable Quality Level 2
S AQL .65 Level III - Take a particular component off 100% Inspection AQL - Acceptable Quality Level 4
D Difficult Inspection Level/AQL - Verifying it is the correct part AQL - Acceptable Quality Level 5
W How to choose the correct General Inspection Level & AQL level...? AQL - Acceptable Quality Level 5
S Using AQL to get true random sampling using General Inspection Level II AQL - Acceptable Quality Level 4
V Receiving Inspection AQL - Am I allowed to just pick a AQL? Inspection, Prints (Drawings), Testing, Sampling and Related Topics 10
L How to calculate the Probability of Deficiency of the AQL of an Inspection AQL - Acceptable Quality Level 16
A Inspection Plans - How to choose AQL (MIL STD 105E) Excel .xls Spreadsheet Templates and Tools 1
L Who and when to determine AQL for our product inspection AQL - Acceptable Quality Level 1
E Translating AQL to a Production Line Inspection Plan AQL - Acceptable Quality Level 14
I Medical Device Receiving Inspection AQL AQL - Acceptable Quality Level 5
J Multiple AQL's within same Inspection Report AQL - Acceptable Quality Level 6
R AQL Inspection Interpretation - AQL Percentage Inspection Methods AQL - Acceptable Quality Level 11
S What if I find a defect after AQL (Inspection)? Pharmaceuticals AQL - Acceptable Quality Level 1
J Incoming Inspection AQL Sampling of Bulk Textiles AQL - Acceptable Quality Level 3
T AQL Sample Size for Battery Inspection AQL - Acceptable Quality Level 10
L Is AQL necessary for ISO 9001 receiving inspection? AQL - Acceptable Quality Level 24
Q Final Inspection lot failures - AQL based final acceptance AQL - Acceptable Quality Level 3
Douglas E. Purdy How AQL Inspection & Test corresponds to Control of Nonconforming Product AQL - Acceptable Quality Level 11
L Incoming (Receiving) Inspection - Is it really necessary that we follow the AQL? AQL - Acceptable Quality Level 7
B 4.10 Inspection and Testing - Do we have to do AQL (MIL-Std-105) sample inspection? AQL - Acceptable Quality Level 3
W LTPD, AQL, Ppk and Cpk validation sampling plan table Inspection, Prints (Drawings), Testing, Sampling and Related Topics 0
R AQL, Consumer Risk and MA Statistical Analysis Tools, Techniques and SPC 2
A AQL - How to count samples with defects for each defect class AQL - Acceptable Quality Level 17
T Defining sampling plan for different AQL AQL - Acceptable Quality Level 3
S ARMY AQL - Requirements which don't have an AQL associated with them Manufacturing and Related Processes 2
M AQL table - I need to sample 1250pcs AQL - Acceptable Quality Level 3
Nicole Desouza Sampling plan for a customer who wants AQL 1.0 (per ANSI Z1.4) AQL - Acceptable Quality Level 5
V How to interpret AQL sampling tables AQL - Acceptable Quality Level 5
A AQL sampling bags of parts Inspection, Prints (Drawings), Testing, Sampling and Related Topics 5
I Sampling processes - Who must define the AQL level? AQL - Acceptable Quality Level 9
J AQL for Effectiveness Check - What AQL tiers to use on this type of sampling? Nonconformance and Corrective Action 9
S AQL Inspector's Rule - bring into CQE Exam? Professional Certifications and Degrees 5
N The question asks about sampling plans and AQL Reliability Analysis - Predictions, Testing and Standards 5
K Defining Acceptance Quality Level, I need clarity on AQL 1.5, 2.5, 4.0 AQL - Acceptable Quality Level 5
L Established a c=0 "AQL" or "RQL" table AQL - Acceptable Quality Level 5
A AQL Sampling Plan SOP / WI - Medical Device Industry Inspection, Prints (Drawings), Testing, Sampling and Related Topics 14
C Example Work Instruction/Procedure for AQL (Acceptable Quality Level) AQL - Acceptable Quality Level 4
P Setting Acceptance Quality Limits (AQL) for New Medical Devices ISO 13485:2016 - Medical Device Quality Management Systems 4
K AQL for Sterile Product - Laminate Tubes 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 5
M How to Mathemetically Derive the AQL Tables given Lot Sizes AQL - Acceptable Quality Level 5
L AQL ANSI z1.4 & z1.9 - What are the differences between these 2 standards? AQL - Acceptable Quality Level 5
P RQL/AQL from Attribute Data Six Sigma 1
B Designing a Sampling Plan - AQL AQL - Acceptable Quality Level 19
S Determining Sample Size - AQL & LQ AQL - Acceptable Quality Level 10

Similar threads

Top Bottom