QualityInspection.orgYou are here:Home/Quality Control Tips/ What is the AQL, and when it is applicable?NOVEMBER 28, 2011BYRENAUD ANJORANWhat is the AQL, and when it is applicable?The AQL tables are statistical tools at the disposal of buyers (for product inspections). They help determine two key elements: How many samples should be picked and inspected, among a batch of product or parts? Where is the limit between acceptability and refusal, when it comes to defective products?The need for an objective measurement of qualityIn certain product categories, there will be defective products in virtually every production batch. It is often true even after the manufacturer has checked each individual product and has repaired the defective ones, since visual inspection is not 100% reliable.Therefore, in many supplier/buyer relationships (particularly when the application does not result in life or death outcomes), the supplier isnotexpected to deliverdefect-freegoods. The buyer needs to control the quality of purchased goods, since he does not wanttoo manydefects. But what does too many mean?How to set the limit between acceptability and refusal in a way that can be agreed upon and measured?Definition and application of AQLThe limit, as described above, is called the AQL. It stands for Acceptance Quality Limit, and is defined as the quality level that is the worst tolerable (source:ISO 2859-1 standard).For example: I want no more than 1.5% defective items in the whole order quantity, on average over several production runs with that supplier means the AQL is 1.5%.In practice, three types of defects are distinguished. For most consumer goods, the limits are: 0% for critical defects (totally unacceptable: a user might get harmed, or regulations are not respected). 2.5% for major defects (these products would usually not be considered acceptable by the end user). 4.0% for minor defects (there is some departure from specifications, but most users would not mind it).These proportionsvaryin function of the product and its market. Components used in building an airplane are subject to much lower AQL limits.Parametri de testareTestarea rulmenilor se execut n conformitate cu standardul ISO 2859 i este mprit pe trei nivele: AQL 0.01 ("key items"); cuprinde testarea duritii, a crpturilor i a caracteristicilor. n cazul rulmenilor EMQ (electric motor quality) se vor testa suplimentar suflul i vibraiile, AQL 1.0 ("main items"); al doilea nivel de testare cuprinde testarea dimensiunilor rulmentului, ventilarea interioar radial, ... > AQL 4.0 ("sub- items"); este ultima faz a testrii i cuprinde testarea magnetismului, a aspectului exterior al rulmentului, ambalarea

Fiecare rulment este testat n ordine dup secvena AQL 0.01 - AQL 1.0 - AQL 4.0. Pentru ca rulmentul s ncheie testarea cu succes trebuie s corespund tuturor celor trei nivele de testare. n cazul n care la un anumit nivel nu s-a dovedit c este asigurat o calitate corespunztoare testarea se incheie.Tabelele model dup standardul ISO 2859n funcie de cantitatea unui anumit tip de rulment comandat de o anumit instituie se va alege un numr aleatoriu de rulmeni care este stabilit de tabel.S presupunem c aceast cantitate reprezint 10.000. Din acestea la laborator se aleg aleatoriu 80 de bucai de rulmeni care vor fi testate n conformitate cu nivelele enumerate anterior. Din acest tabel se vede c la nivelul de testare (AQL 0.01) fiecare dintre mostrele testate trebuie s satisfac toate condiiile.La nivelul urmtor (AQL 1.0) se va modifica cantitatea cu 2 care este numrul rulmenilor testai care nu au trecut faza testrii la primul nivel. La cel de al treilea nivel cantitatea limit admis a rulmenilor care nu au trecut testul este de 7.

http://www.codex.si/ro/asigurarea-calitii/parametri-de-testare.aspx

Getting familiar with the AQL tablesBefore using the AQL tables, you should know three parameters: The lot size. If you ordered different products, the quantity of each product is a lot size, and it is advised to perform separate inspections for each lot. If you ordered only one product, the lot size is the total batch quantity. Theinspection level. Different inspection levels will command different numbers of samples to inspect. In this article, we will stick to the so-called level II under normal severity and to single sampling plans. The AQL level appropriate for your market. If your customers acceptvery few defects, you might want to set a lower AQL for both major and minor defects.There are basically two tables. The first one tells you which code letter to use. Then, the code letter will give you the sample size and the maximum numbers of defects that can be accepted.First table: sample size code letters

How to read this table?If you follow my example, I assume your lot size is comprised between 3,201 pcs and 10,000 pcs, and that your inspection level is II. Consequently, the code letter is L.Second table: single sampling plans for level II inspection (normal severity)

How to read this table?Your code letter is L, so you will have to draw 200 pcs randomly from the total lot size.Besides, I assume you have set your AQL at 2.5% for major defects and 4.0% for minor defects. Therefore, here are the limits: the products are accepted if NO MORE than 10 products with major defects AND NO MORE than 14 products with minor defects are found.For example, if you find 15 products with major defects and 12products withminor defects, the products are refused. If you find 3 with major defects and 7 with minor defects, they are accepted.Note:inquality inspections, the number of defective products is only one of the criteria. It is sometimes called quality, or quality findings. The other criteria are usually on the inspectors checklist, which typically includes: Packaging conformity (barcodes, inner packing, cartons, shipping marks). Product conformity (aspect, workmanship). If all the products are in red color instead of orange, there is no need to count each sample as a defect. It makes more sense to refuse for product conformity. Specific tests defined in the inspection checklist (they might not be performed on all inspected samples if they are time-consuming or destructive).Frequently Asked Questions about AQLQ: So, basically I have to authorize the factory to produce some defects?A: In theory no.Thats why the AQL was renamed, from acceptable quality level to acceptance quality limit. It is a limit (and a loose one at that).Here is what the ISO2859 standard says:Although individual lots with quality as bad as the acceptance quality limit may be accepted with fairly high probability, the designation of an acceptance quality limit does not suggest that this is a desirable quality level. Sampling schemes [...] are designed to encourage suppliers to have process averages consistently better than the AQL.Note that, in practice, using these statistics means you assume the factory cannot reasonably be expected to turn out 100% good quality.Alternatively, you can choose an acceptance on zero plan. As soon as one defect is found, the inspection is failed. But you can impose this to suppliers only in situations where quality requirements are very high (in the auto industry, in aerospace).Q: Based on my AQL, I calculated the proportion of defects authorized. Why dont they correspond to the maximum number of defects authorized?A: It is true. In our example above, 2.5% of 200 samples is 5 samples, but we accept the goods even if 10 samples are found with a major defect.Why this difference? There are heavy statistics behind this issue. To keep it simple, the producers risk is his risk of rejection (based on the random element when drawing the sample) even though his products (if they were all checked) would be accepted. That risk is about 5% in this standard. And, along the same logic, there is a consumers risk and is is around 10%. As you can see, this standard is favorable to the producers side.Q: Why not just say, well check 10% of the quantity, or whatever percentage deemed appropriate?A: Here again, the statisticians tell us it is not that simple. As we go up in the total quantity, the proportion of products checked can decrease,for the same confidence in the inspection results.As you can see in the chart below, the number of samples to check (vertical axis) increases at a slower pace than the total quantity (horizontal axis).

Q: How to choose an AQL limit for my products?A:See this article. It depends on your distribution channel and your products end use.Note that your supplier might refuse AQL limits they estimate as too tight (i.e. too low).Q: What are the reduced and tightened severities?A: They are designed to be used in very specific situations, when a producer is particularly reliable, or on the contrary fails too often.In practice, these severities are seldom used. Most inspections are done in normal severity. Thats unfortunate, because the rules to switch from normal to reduced or tightened are considered a very important part of the standard (actually the evolutions of these rules constituted the main changes from MIL-STD 105A and MIL-STD 105E).Q: What are the limits of a quality control approach based on random sampling and AQL limits?A: There are several limits:1. An AQL limit is a target rather than a maximum. The buyer might have a nasty surprise when receiving a batch of products that passed the inspection.Read more in this article.2. A statistical QC approach does nothing to reduce the defects in the first place.Read more in this article.Q: Where can I learn more about the AQL?If you really want to understand the concept of the AQL, you should spend about 20 minutes watching these 3 videos on Youtube. How to Read the AQL Tables When Applying the AQL tables Does or Doesnt Make Sense Why the AQL tables are not in favor of the buyerSharehareFiled Under:Quality Control Tips

Comments1. Ghulam sabirsaysDecember 15, 2011 at 5:54 pmmy question is this what is 1.5,2.5,4 etc. is this a percentage of faults. if yes than at aql 2.5 there should be 5 defectives allowed. while table says 7 allaowed. what is it ? ChrisGreensaysJune 6, 2014 at 10:54 pmThe reason is that the ISO 2859-1 definition of AQL is simply incorrect. The actual definition of AQL is the percentage of defective parts that is routinely accepted by your sampling plan. Thus, a particular sampling plan for an AQL of 1%, might actually only reject a lot if there are 2% or more defectives. What the 1% means is that if the true failure rate of your process is 1%, you will still, due to the random nature of your sample, get defective rates over 1% sometimes, however, 95% of the time, they will be under 2%. You can think of the actual number of defectives that a particular plan allows as the lower confidence limit of the AQL value. ChrisGreensaysJune 6, 2014 at 10:56 pmCorrection, you can think of the actual number of defectives that a particular plan allows as the UPPER confidence limit of the AQL value. Renaud AnjoransaysJune 7, 2014 at 3:54 amYes I agree, the ISO 2859-1 definition of the AQL is confusing. Thats what I explain in the 3 videos I shot on this topic (see the links at the end of the article). Shahid AlisaysJune 27, 2014 at 10:18 ami would like to ask you from where you got AQL table and what is the document reference number of AQL chart? Renaud AnjoransaysJune 27, 2014 at 10:56 amISO 2859-1 standard. There are other equivalent commercial standards in different countries.2. Renaud AnjoransaysDecember 15, 2011 at 6:06 pmGhulam,It is the percentage of defective products that the buyer is willing to accept in the total population of products.Read the paragraph that starts with Based on my AQL, I calculated above, and it will answer your question.3. karthicksaysDecember 15, 2011 at 8:21 pmI want an Clear definition for AQL ?4. Renaud AnjoransaysDecember 15, 2011 at 8:30 pmKarthick,The AQL is the worst quality level that the buyer is willing to tolerate.5. Mithun kumarsaysDecember 22, 2011 at 5:36 pmhow i decide the lavel of aql according to lot size6. Renaud AnjoransaysDecember 22, 2011 at 9:23 pmMithun,See the explanation below the 1st table, in the article above.7. ALIsaysDecember 29, 2011 at 3:33 pmThanks a lot .It was so useful for me.8. PraveensaysJanuary 1, 2012 at 5:21 pmplease suggest the better system than AQL & why?9. Renaud AnjoransaysJanuary 1, 2012 at 5:30 pmPraveen,First, explain what you dont like with the AQL system, and maybe I can make suggestions10. O.P.Singh ChauhansaysJanuary 9, 2012 at 4:52 pmfor plastic flexiable packaging, there are n number of major and minor defect. how we can make the list.11. Renaud AnjoransaysJanuary 10, 2012 at 11:36 pmO.P.Singh Chauhan,I am not sure I understand What is the order quantity, and what AQL limits would you choose?12. Brian FsaysJanuary 12, 2012 at 6:36 amIve received a request to set an AQL level (which I had set at 2.0%) to:An AQL of 0.065 OR 0/1 reject/accept levelIm not particularly certain what this means. I assume the 0.065 is just a much much tighter % than the 2% I had set (which is rather tight), but the OR 0/1 reject/accept level confuses me. Any idea on what was intended? Does it literally mean 0 rejects for every 1 accept which would be an AQL of 0.0?13. Brian FsaysJanuary 12, 2012 at 6:38 amAnd by the way, good article. Many thanks.14. Renaud AnjoransaysJanuary 12, 2012 at 4:11 pmBrian,0.065% is much stricter than 2.5%. By the way, 2.0% is not in the tables, so you should not use this value.0/1 reject/accept level means that the lot is passed if there is 0 defect, and rejected if there at least 1 defect. In practice it is similar to an AQL of 0.065%, except if your order quantity is above 150,000 pcs (I am assuming level II).15. Daniel FoksaysJanuary 14, 2012 at 4:47 amVery good practise in explaining the AQL and quality level concept.In theory, if the sample size is 125 pcs in an order of 3000 pcs for level II.Is it possible to inspect just 50 pcs or 80 pcs for some non critical portions of the product; like cosmetic of the product?16. Renaud AnjoransaysJanuary 14, 2012 at 11:02 amDaniel,Thanks. To respond to your question: yes it is possible. See the special levels, onhttp://www.qualityinspection.org/inspection-level/.17. AznalsaysJanuary 19, 2012 at 2:53 pmWhat is the different between Special Inspection Level (S-1, S-2, S-3, S-4) and GenEral Inspection Level ( I, II, III )?. Do we need to choose either on or both must be choose?..18. Renaud AnjoransaysJanuary 19, 2012 at 9:47 pmAznal,Seehttp://www.qualityinspection.org/inspection-level/. Special levels are usually chosen for tests that destroy the product, or that take a lot of time (i.e. when you need a really small sample size).In over 90% of cases, importers use general level II.19. AdamHsaysFebruary 10, 2012 at 7:18 amHi,what is the probability that i will accept a lot more than 1,5% defective if i use AQL 1,5 to inspect?20. Renaud AnjoransaysFebruary 15, 2012 at 12:18 amAdamH,The standard does not indicate this probability It is supposed to be adapted to a normal buyer/supplier relationship.21. Ravi.ShirolsaysMarch 1, 2012 at 8:26 pmIF LOT QUANTITY IS 20 WHAT IS THE AQL22. Renaud AnjoransaysMarch 1, 2012 at 8:37 pmRavi,You can see onhttp://www.sofeast.com/aql-tables. Il level II, you should check 5 pcs.23. ObserversaysMarch 3, 2012 at 10:00 pmI love how the majority of the comments are from Asians and South Asian named people. You would Google and searched for the meaning and definition of AQL is fantastic. Most people I work with who are Caucasoid couldnt care less and dont want to know frankly. The devil is in the detail as always you impress me.24. Renaud AnjoransaysMarch 3, 2012 at 10:20 pmObserver,Yes, its funny. Lots of suppliers who wonder what their buyer is talking about, too.25. S.QaisersaysMarch 15, 2012 at 2:21 pmPlease also describe the method how did you calculate the 200 pcs of shipment samples for inspection if the shipment volume up to 3000-10,000 pcs ?I appreciate your quality inspection tips.26. Renaud AnjoransaysMarch 15, 2012 at 3:32 pmS.Qaiser,It is not a calculation. For the letter L, the inspector should pick 200pcs.Look at the 1st and the 2nd tables in the above article.27. abdelazizsaysMarch 28, 2012 at 5:14 amthanks very much but i need more explain plz28. Renaud AnjoransaysMarch 28, 2012 at 10:51 amAbdelaziz,Not sure how I can help Please be more specific.29. sanjaysaysMarch 29, 2012 at 3:00 pmIs there any AQL level 2.54 ?30. Renaud AnjoransaysMarch 29, 2012 at 3:24 pmSanjay,No. Nothing between 2.5 and 4.0.31. sanjaysaysMarch 31, 2012 at 1:28 pmThanks for the information. Please advise which AQL we should apply to inspect handicraft articles (Metal Handicraft Items).32. Praveen SrivastavasaysMarch 31, 2012 at 7:42 pmsuggest critical,major and minor defects in floor covring goods (carpet,Bath mats,pitloom/fraloom rugs,Breided rug etc.33. rajeev kumar srivastavsaysApril 2, 2012 at 5:56 pmdear sir:-i want to know according to A. Q. L.2.5 & 4.0 ORDER QUANTITY IS 1000 PCSHOW MUCH CHECKED PCS IN 1000PCS34. Renaud AnjoransaysApril 2, 2012 at 6:17 pm80 pieces out of 1,000 pieces, in level II (as explained in the above article).35. sanjaysaysApril 3, 2012 at 4:26 pmDear Renaud, please advise which AQL we can apply to inspect Metal Handicrafts items, as due to handicrafts no 1 piece is simillar to another, so how can we inspect as per AQL.36. Renaud AnjoransaysApril 3, 2012 at 4:28 pmSanjay,You can certainly do like in the example of this article. Level II, 0/2.5/4.0.37. JohnsaysApril 5, 2012 at 11:55 pmThanks for the illuminating article.Is there any systematization behind the random drawing of the samples?For exemple, I have a lot of 5,004 units divided into 139 master packages with 36 units each. Each of the masters contains 6 inner packages with 6 units in each inner. How will the inspector choose his samples? Since according to the table (based on level 2) he will need to inspect 200 units, does it necessarily means that there will be at least one sample from each of the master packages? Will the samples always be from the top inners or from the bottoms as well?Thanks for you help.38. Renaud AnjoransaysApril 6, 2012 at 12:08 amJohn,Interesting question. There are no indications about this in the standard.Usually, here is the way it is done:- The sq.root of 139 is between 11 and 12, so the inspector will pick at least 12 master cartons.- He will take 16 to 17 pcs per master carton, and will make sure the total is 200 pcs.- He will probably try to pick pcs in 2 or 3 of the inner cartons, inside each master carton. There is no rule for that, except that he should take some inner cartons from different parts (top, center, bottom, front, back) of the master carton, and same thing for the pieces inside the inner cartons..39. JohnsaysApril 6, 2012 at 12:44 amHi Renaud,Thank you for your prompt reply.Is this somthing I should specify in advance to the company who preform the inspection? i.e. you need to inspect at least X master cartons and at Y inner carotons from different parts in order to avoid a situation where all the samples will be picked up from the same places?Is it common to determine this with the service provider when ordering the inspection?Once again, thank you for your assistance.40. Renaud AnjoransaysApril 6, 2012 at 1:31 amJohn,If you are working with professionals, no need to specify it.41. sapnasaysMay 2, 2012 at 3:18 ami want to print out this page42. MigodsaysMay 8, 2012 at 10:39 pmif there is more than one defect on a garment, how is this counted Renaud AnjoransaysMay 8, 2012 at 10:42 pmAs the most severe defect found on that garment.But make sure the description of the defect shows that there were several defects.43. HesincsaysMay 10, 2012 at 12:10 amANSI Z4, In the table, there are AQL of 100, 150, 250, etc. but the table reads that this number represents Percent non-conforming and Nonconformaties per 100 items. How can they be greater than 100 with that definition? Is it allowing for multiple non-conformances per unit?44. Joseluis VillarrealsaysMay 15, 2012 at 8:36 pmI have a doubt about Mil-Std-105d Table for Single sampling plan for Normal inspection (Master table). If I have a lot of 100 units my sampling size code letter is D for S-4 Level, so sample size is 8 pcs, and if I apply 0.65 AQL there is an arrow down that goes for the acceptance criteria; 0 accept, 1 reject the lot, my doubt is; do I have to go down as the arrow shows and interpolate with sample size so then my sample size has to be 20 pcs, is that correct? can somebody help me! Renaud AnjoransaysMay 15, 2012 at 11:52 pmThe best is to inspect 20 samples and apply the [0,1] AQL.But it is not an obligation, just a suggestion for the most purist among us.It is fine to inspect 8 samples and also reject the lot if you find at least 1 defect.45. Joseluis VillarrealsaysMay 15, 2012 at 11:32 pmMr. Renaud Anjoran, please help!46. Joseluis VillarrealsaysMay 16, 2012 at 7:55 amThank you very much for you opinion and help.Another case; If I have a lot of 1500 units my sampling size code letter is G for S-4 Level, so sample size is32 pcs, and if I apply 0.65 AQL there is an arrow up that goes for the acceptance criteria; 0 accept, 1 reject the lot, my doubt is; do I have to goup as the arrow shows and interpolate with sample size so then my sample size has to be 20 pcs, is that correct? Renaud AnjoransaysMay 16, 2012 at 9:48 amSame logic here. No need to check 32 samples just check 20 samples and reject if you find at least 1 defect. Hengsun590saysJune 7, 2012 at 2:27 pmthanks behalf, If i have lot size 35,001 to 150,000 my samling size code is N for S-4 , so sample is 500 or 1250? Hengsun590saysJune 7, 2012 at 3:33 pmthanks behalf, If i have lot size 35,001 to 150,000 my samling size code is N for S-4, if I apply 0.04 what is the sample 315 or 500 or 1250? some one help please Renaud AnjoransaysJune 7, 2012 at 3:44 pmNo, your letter is J for S-4 level, and you should check a sample of 80 pcs.47. SakhaoutsaysJune 17, 2012 at 8:07 pmAdjust new AQL chart .For help us any student .Thanks. Renaud AnjoransaysJune 18, 2012 at 4:33 pmThere is no way to adjust it without corrupting it48. Ranajawad83saysJune 27, 2012 at 6:23 pmthanx i realy got my point understand49. MajoegongsaysAugust 1, 2012 at 2:35 amMa Joe GongThank you very much for your opinionI want to know qty special inspection level s-1; s-2: s-3 and s-4, its same with 1Pcs, 2Pcs, 3Pcs and 4pcs? Renaud AnjoransaysAugust 1, 2012 at 8:20 amNo, it is not the same. The sample size depends on the lot size.50. PetersaysAugust 3, 2012 at 2:01 amDoes a Major defect also count towards the Minor defect count?Using your above example (3,201-10,000, level II, 2,5&4), what if the result of the inspection was 9 Major and 13 Minor. Do the Majors also count towards the Minor total, for a total of 22 defects that are at least Minor? Or, are they always kept separate? Renaud AnjoransaysAugust 6, 2012 at 9:18 pmNo. Better always keep them separate. Tycho GrouwstrasaysJanuary 30, 2013 at 12:20 pmBetter? Actually keeping them separate has funny consequences. If the minor defective allowance is exceeded a bit while the major/critical defect allowances still left some spare room, the AQL system would effectively recommend suppliers to smash a few products so that all allowances would be met again. Renaud AnjoransaysJanuary 30, 2013 at 12:25 pmThats right. Dont ask me to defend that methods logic I am just explaining how it is supposed to be applied. JohnGuosaysMarch 12, 2013 at 2:49 amAlthough it seems like it, this is actually not right thinking. That`s because there might be totally different manufacturing mistakes that can lead to major and minor mistakes. So if you have found only 1 major defect and then more minor defects you cannot group them together since you might end up with a whole bunch of products having the same minor mistake. Then, although there would be only a few pcs of major ones the whole lot would become unacceptable by the end client. AQL has its flaws anyway, like any system i guess, and can be very unfair for the supplier or the buyer, (usually the buyer though). Asep Surya PurnamasaysNovember 27, 2013 at 8:17 amIn the last time company, we keeping 2 point minor defects = 1 point major defect. xuansaysOctober 25, 2013 at 1:38 pmdear Mr Renaud,Separate and not separate? is there any document write about this? pls share to me. If I choose not separate, Total is larger 14, I will reject it. is it right? Renaud AnjoransaysOctober 28, 2013 at 1:27 pmSorry but your questions are not clear xuansaysNovember 8, 2013 at 2:48 pmFollow your example, the second table , If I choose the lot size 200, AQL 2.5 and 4.0. I found 8 defects( AQL=2.5) and 8 defects (AQL=4.0). It mean total defect is 16.Can I approve for this lot? Renaud AnjoransaysNovember 8, 2013 at 2:52 pmYes.51. PetersaysAugust 3, 2012 at 2:04 amIs there any benefit to performing the same inspection on the same lot?Lets say that my factory does a 2.5 AQL Level III inspection. Is there any benefit to having a 3rd party inspect the same lot at 2.5 AQL Level III after the factory completes its inspection? Renaud AnjoransaysAugust 6, 2012 at 9:18 pmUsually yes. The third party inspectors might be better trained, and will probably tell you the truth (they have no interest in lying to you, while the seller may have such an interest).52. Devnath PillaisaysAugust 24, 2012 at 1:14 pmis the lot size refereed here is actual packing by supplier or is been refereed to P.O quantity. for ex : if p.O quantity is 1200 pcs & actual packing by supplier is 1210 pcs so how many samples i need to choose 125 or 80 samples Renaud AnjoransaysAugust 24, 2012 at 5:25 pmThe lot quantity is the actual quantity to ship.Special case: if the supplier is late in packing and some pieces to be shipped are still unpacked, they are part of the lot.53. Sital k kshetrisaysAugust 25, 2012 at 2:04 pmIf i am buying 100000 pairs of loge and coated on the pack aql1.5 so what does it men?It means 1500 pairs defected?Plz help me to solve the problem. Renaud AnjoransaysJanuary 24, 2013 at 9:54 pmNo, its a bit more complicated than that Youd have to read the article above.54. Sital k kshetrisaysAugust 25, 2012 at 2:06 pmIf i am buying 100000pairs of gloves and on the pack coated aql1.5 so what does it mean?Does it mean 1500 pairs defected?Plz solve my problem any one/ Renaud AnjoransaysAugust 28, 2012 at 5:00 pmI dont understand the question, sorry55. Gail BirkssaysAugust 26, 2012 at 1:41 amexcellent explanation of what can be a complex concept. thanks Renaud AnjoransaysSeptember 26, 2012 at 11:30 amThanks Gail!56. EriksaysAugust 28, 2012 at 5:04 pmHi Renaud,thanks, your explanation is very simply.I have a question: are there values AQL internationally recognized for several items?. I would like to determine a AQL for the control assembly of the components of fittings nylon and aluminum. Thank you. Renaud AnjoransaysAugust 28, 2012 at 5:17 pmYes, this standard can be applied on any products (finished or unfinished), instances of a process, etc.But you should adapt the values of the AQL to your product and your market. Clck on the last link, at the bottom of the article, if you are wondering how to do that.57. Manjunath e BhutesaysSeptember 21, 2012 at 6:25 pmThe quality plan submitted to our customer has been commented for Quantum of inspection as per ISO 2859 & they have not mentioned Lot size, Inspection level, & AQL level, Pl clrify What does it mean? Renaud AnjoransaysSeptember 21, 2012 at 9:01 pmYou can click on QC basic concepts in the menu of this site, and you will have some responses.Lot size is the batch size.58. TimbosaysSeptember 25, 2012 at 12:05 amWhat about a product that contains items, eg: I sell boxes of nails in packs of 100. For a lot size of 2000 boxes insp level 2 gives K, sample size 125 boxes defects allowed 10 and 14, now what happens if he opens the boxes and looks at the nails, are the defects still 10/14 or is our sample size to be changed to 2000200 = 200,000 pcs? He would now have to inspect P/ 800pcs, 21/21?Also the upper limit is 21, so 10 million pcs cannot have more defects than 500K pcs, does not seem fair? Renaud AnjoransaysSeptember 25, 2012 at 10:56 amTimbo,I strongly advise you to consider that the lot is 200,000 nails, rather than 2,000 boxes. Count it all in pieces.Seehttp://www.qualityinspection.org/iso-2859-sets/for more details.59. Roy MartinezsaysOctober 15, 2012 at 9:31 pmIs there an exception to critical defects having an inspection that passes ? Or is it always 0/1 Renaud AnjoransaysOctober 15, 2012 at 9:36 pmYou mean, does it happen that buyers accept a certain proportion of critical defects? I cant tell for sure, but it probably happens. Its all up to the buyer (what is a critical defect, and what the limit for this category of defects is).60. AdriansaysOctober 31, 2012 at 11:47 amA very nice explanation, i would like to ask some question about AQL:1. If I found 1 major and 1 minor defect on one unit, which type of defect is used, major (cause its greater than the minor) or count separately 1 major defect and 1 minor defect?2. example lot size 281-500 with sample size 50, Major 1,0 ( 1.5% does not mean that, for each lot, the result is failed as soon as there are more than 1.5% of defects. It allows for variation from lot to lot, and tries to avoid rejection of a lot as long as the average of the lots might be under the limit.98. AhaisaysJune 25, 2014 at 9:11 amHi Renaud,I have received a QA inspection report from our supplier based on AQL Level II and sampling Qty is 200. the inspection checklist contains 18 different measurments on each part and 5 test recorders for any of these 18 measurements. shouldnt it contain 200 test recorders of any of these 18? Thanks Renaud AnjoransaysJune 25, 2014 at 12:40 pmNot necessarily. 200 samples means the visual inspection is on 200 samples. But the tests that take a little longer are usually done on a smaller sampling size. AhaisaysJune 25, 2014 at 1:03 pmwe are talking about measurements deviations around 0,2 mm and visual inspection does not work. so supplier can actually pick 5 samples out of 4000 Batch Qty and still hoping to capture some faulty units? Renaud AnjoransaysJune 25, 2014 at 1:15 pmI cant make a judgement because I dont know what type of product it, made with what process, etc.But, in some cases, checking just 5 pieces is sufficient to establish conformity (or lack thereof) without going more in depth, with a reasonable degree of certainty.Note that, if you represent the customer, you are the party responsible for estimating whether this sampling plan makes sense. If you dont specify this before the inspection, it means you delegated this judgement to another party, and protesting afterwards does not really make sense.99. FranksaysAugust 12, 2014 at 8:51 pmHello, I am trying to implement an sampling plan where we have a batch size of 480, and a AQL of 0.25. For a batch size of 480 the general inspection level II code is H. This results in a sample size of 50 where everything must pass the inspection. When asked to explain what an AQL of 0.25 means, I said that an AQL of 0.25 means that if we pass our sampling inspection of 50 parts, then we can assume that the percentage of nonconforming parts in the lot is 0.25% (1 out of 400 parts will be nonconforming). Is that an accurate explanation?On a slightly different note, one of my associates noticed that the AQL values go above 100, and actually go all the way to 1000 on my table. Does that mean at 100 you have 100% nonconforming parts, and what would 1000% mean? This led to confusion, and some apprehension of what the AQL of 0.25 truly meant. Renaud AnjoransaysAugust 13, 2014 at 1:24 amNo, I would not use this definition. You should say you want no more than 0.25% defective items in the whole order quantity, on average over several production runs with the same supplier.Yes it goes over 100, for cases where several defects are counted on the same product.100. Kent LsaysAugust 14, 2014 at 7:16 pmHi RenaudNicely done article and replies.I have a question on zero acceptance sampling plans. They do not actually use AQL but rather the term Associated AQL. In the sampling plans above it is my understanding that an AQL of 1% would indicate there is a 95% chance of a lot containing 1% or fewer defects would be accepted (or a 5% chance of the same lot being rejected producer risk). Using the OC curve you can determine the likelihood of rejecting other lots with higher or lower defect levels.How do I make similar determinations on C=O plans?I have Nicholas Squeglias book, but I am still struggling with an explanation. My suppliers are pushing for me to use the ANSI/ASQ plan but I prefer the C=0.Thanks101. RenaudsaysAugust 15, 2014 at 2:57 pmHi Kent, Id recommend you watch this video where I explain these concepts:http://www.youtube.com/watch?v=8bUe8nQpI0s.102. MINHTRIETsaysSeptember 3, 2014 at 7:29 pmHi Renaud,I would like to share with you my case. I have an order of 1200 pieces.My AQL define 2 check lists1. Visual check / level S-4 ==> I have to control 32 pieces in visual2. Functional check/ level S-2 ==> I have to control 8 pieces in functionalQuestion1:I have to pick from the carton boxes 40 pieces right? (32+8 = 40)OrCan I select just 32 pieces and then inside 32 pieces, I will take 8 pieces to control the functional? What is the right way?Case2: Visual check / level S-4 ==> 32 pieces in visual with Maximum 3 minor defects and 1 major defectQuestion2If I control 1 piece (the first piece), I found down in this piece, there are 4 minor defects and 2 major defects in visual. (in ONLY 1 piece)==> It is out of our tolerance of defects==> Not ok. No need to control more. Order failed! Is it right?OR ==> I count it is 1 defective with 1 major defectI continue the 2nd piece and my level of acceptance is reduced to 3 minor defects and 0 major defectsSo we count the defects Or defective?Thank you for your advice RenaudsaysSeptember 4, 2014 at 3:23 amHere are my responses:Question 1: you can pick just 32 pcs.Question 2: you just count 1 major defect. Count the defectives. MINHTRIETsaysSeptember 4, 2014 at 6:22 amThank you so much. Nice day!!!103. SuksaysSeptember 13, 2014 at 4:02 amI wrote many things and it got me error 405well Ill do it again.First of all, thanks for the article it was a really good explanation but as my english is not so good there are things that I couldnt understand quite well.Well, in early 2015 I am going to open a chinese company branch in Brazil and I have to do inspections of the pcs based on the AQL, right?Well they told me that the AQL is 0.4 but in the table that you posted on the article there is no AQL 0.4 so or they wrote it wrong for me and they meant 4.0 or is there an AQL 0.4 ?Is there any document or article that defines what are the major and minor defects of a product or is it up to the company to decide it?? Ill be producing equipments for health quality and stuff like that, as they are health/medicinal equipments if there any document or article that defines the defects?Another one that I couldnt understat quite well, In the exemple that you gave in the article above, you show AQL 2.5 and 4.0 and you set 2.5 for major defects and 4.0 for minor defects, do I have to choose 2 AQLs or can I just set AQL 4.0 for both ? If I can set it with 1 AQL for both in 4.0 (for example in Level II / Code L) I would have to inspect 200 pcs and in there I could have 14 or less pcs with defect, right ? But as I set both (minor and major) defects on AQL 4.0 I could have 14 or less pcs with major defects AND 14 or less for minor defects? Or is it 14 or less of ALL?If you could send me an article or a document with a simplyfied explanation, I think it would help me.PS : Sorry for my bad english, as I am a korean and I lived in Brazil since 1998 my english is not so good.Best Regards,Suk Renaud AnjoransaysSeptember 14, 2014 at 4:03 am0.4 is not among the preferred AQLs, so it is probably a typo.It is up to the buyer to decide what constitutes the different classes of nonconformities (major or minor) and the AQL for each. The AQL for each can be the same, if deemed appropriate. SuksaysSeptember 15, 2014 at 12:18 amSooo what youre saying is that if the AQL is the same for both minor and major defects, I dont need just < or = 14 (in case of 200 pcs ) for both of them ?? it would be a total of 28 pcs?? RenaudsaysSeptember 15, 2014 at 1:26 amIf the AQL is the same for both minor and major defects, the inspection is failed is 15 or more defects are found either in the minor or in the major category (or in both). GuillesaysOctober 9, 2014 at 7:51 pmIf you can be more clear, if we inspect 200 pc and find 11 major and 6 minor is that a pass or fail?in other words are they allowed 10 major and 14 minor on same 200 pc?if more than 10 major alone is it a fail ?if more than 14 minor alone is it a fail?what about 7 major and 10 minor is that a fail?In that case (you find 11 major and 6 minor), it is a fail.Yes they are allowed 10 major and 14 minor on same 200 pc.7 major and 10 minor is passed.ABOUT MEHello, my name is Renaud Anjoran and I have worked in the Chinese manufacturing world since 2005.My company performs factory audits, quality inspections, project management, and factory process improvements.Contact me!GET UPDATES IN THE MAILTop of Form

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