Hello friends

In need some help to understand if I need AQL for incoming inspection or not for ISO 9001.
I am trying to implement ISO 9001 in the factory where I work, and I don't know what to do.
If I don't need AQL, how I will establish the appropriate sample for inspection.
If I need AQL, which is more proper.

Thank all of you very much. :thanx:

Hello friends

In need some help to understand if I need AQL for incoming inspection or not for ISO 9001.
I am trying to implement ISO 9001 in the factory where I work, and I don't know what to do.
If I don't need AQL, how I will establish the appropriate sample for inspection.
If I need AQL, which is more proper.

Thank all of you very much. :thanx:

"AQL" (acceptable quality level) isn't necessarily related to sampling inspection; it can be applied as a result of sorting, for example. What do you do now to verify purchased material before use? Some companies do a lot of receiving inspection using standardized sampling plans (what you refer to as "AQL," I presume) and others little or none, opting instead to develop suppliers and rely on them to provide conforming material. There is no ISO requirement for receiving inspection, per se.

"AQL" (acceptable quality level) isn't necessarily related to sampling inspection; it can be applied as a result of sorting, for example. What do you do now to verify purchased material before use? Some companies do a lot of receiving inspection using standardized sampling plans (what you refer to as "AQL," I presume) and others little or none, opting instead to develop suppliers and rely on them to provide conforming material. There is no ISO requirement for receiving inspection, per se.


Thank you Jim
I had some audits frome our costumers, and they ask me to show the criterions for incoming inspections. I don't have options to not verify the purchased material., and this inspections need to be veriy documented. I think, I can't verify 2000 part like 50000.
What do you suggest ?

Many, many thanks .

Thank you Jim
I had some audits frome our costumers, and they ask me to show the criterions for incoming inspections. I don't have options to not verify the purchased material., and this inspections need to be veriy documented. I think, I can't verify 2000 part like 50000.
What do you suggest ?

Many, many thanks .

You didn't answer the question--what do you do now? What, if any, specific objections did your customers raise? What sort of problems do you have with acceptance of nonconforming material?

As a starting point, you should use the Cove's search function, starting with the threads listed towards the bottom of this page. There's lots of information here regarding sampling inspection and sampling plans.

You didn't answer the question--what do you do now? What, if any, specific objections did your customers raise? What sort of problems do you have with acceptance of nonconforming material?

As a starting point, you should use the Cove's search function, starting with the threads listed towards the bottom of this page. There's lots of information here regarding sampling inspection and sampling plans.

Sorry because I din not answer to your question ?
Yesterday I had a free day, and I was not to work.

What I am doing now ? - to answer the question;

When I recive the suplly material I have a chekclist.
In my chekclist I am looking to:
1. If the material exist in my approved material list
2. if the supplier are approved
3. Documents (quality certificate)
4 I evaluate the conformity of quality certificate with tehnical characteristics
5 compare the material with master specimen
6 pack condition

(this is for plastic material . I work in a plastic mold injection factory)
For ather materials (pipes)
1.I masure diferent kind of dimensions
2 ...

But I don't know the proper sample size for quantity recived.

I had read the discution from forum.
Thank you for your time :thanks:

Hello,

I don't think AQL is a must. But it is a method which might be given up.
As an automotive supplier,the quality acceptance levl is zero. If one part is found with defect, the whole lot should be rejected no matter how large is the lot size.

I always use a fixed sample sie for receiving inspection. But th eacceptance cretiria is always zero !!! And there is no problem at all for customer auidtand the third aprty audit.

Best Regards,
Johnson Shao
:agree1:

Hello,

I don't think AQL is a must. But it is a method which might be given up.
As an automotive supplier,the quality acceptance levl is zero. If one part is found with defect, the whole lot should be rejected no matter how large is the lot size.

I always use a fixed sample sie for receiving inspection. But th eacceptance cretiria is always zero !!! And there is no problem at all for customer auidtand the third aprty audit.

Best Regards,
Johnson Shao
:agree1:

Thank you very much for your advice
My question is: How can I know the size of my sample to be relevant ?
Which are the rules to establish the size of my sample ?
Is percentage from the quantity recived ?

Best regards
God bless you



Thank you for your ansver

Hi Luciano,

If you want to use AQL then this is what you need:

ISO 2859-1: Sampling procedures for inspection by attributes - Part 1: Sampling schemes indexed by acceptable quality limit (AQL) for lot-by-lot inspection.

Determine what quality level you can accept, and simply use the tables given in the standard to determine sample size and rejection criteria.

However, in order to help you further you need to elaborate a bit on what kind of raw materials you want to inspect. Is it compounds, foils, moulded items or?????

Hi Luciano,

If you want to use AQL then this is what you need:

ISO 2859-1: Sampling procedures for inspection by attributes - Part 1: Sampling schemes indexed by acceptable quality limit (AQL) for lot-by-lot inspection.

Determine what quality level you can accept, and simply use the tables given in the standard to determine sample size and rejection criteria.

However, in order to help you further you need to elaborate a bit on what kind of raw materials you want to inspect. Is it compounds, foils, moulded items or?????


Thank you very much .
There is another way to evaluate by sampling without AQL my incomings part ?
Usualy a recive a plastic raw material (PP, PE-LD, PE-HD, ABS....); colour pigments, metal pipes.
How can I establish the corect size of the sample ?
For me it's Ok tu use AQL, but if it's not necessary I don't want to complicate the sistem (we are not a big factory approximately 100 peoples, ) but allso I want to assure the quality of incomings
Many, many thanks.
God bless you

Thank you very much .
There is another way to evaluate by sampling without AQL my incomings part ?
Usualy a recive a plastic raw material (PP, PE-LD, PE-HD, ABS....); colour pigments, metal pipes.
How can I establish the corect size of the sample ?
For me it's Ok tu use AQL, but if it's not necessary I don't want to complicate the sistem (we are not a big factory approximately 100 peoples, ) but allso I want to assure the quality of incomings
Many, many thanks.
God bless you

Another way of doing your incoming inspection would be to have some clear parameters with regards to your compounds. The more precisely you specify the compounds the better the certificates you get. So be precise and get your supplier to document via certificates that the compound is within specifications. If you want an extra certainty you can use a polymer testing system like the Davenport MFI-9. This measures the melt flow of the compound and can be used as an indication of the abilities of the compound.

Good luck :)

Luciano,

I always prefer to apply ANSI Z1.4 for incoming sampling as it is based on statistical approach. It also helps me to avoid lot of customer queries. When I tell them that I apply ANSI Z1.4, they are comfortable (and definitely I am :D )

In my procedure, I have pasted the ANSI tables and an example to show how to select the total num ber of cartons and no. of units to be sampled.

Thank you very much for your advice
My question is: How can I know the size of my sample to be relevant ?
Which are the rules to establish the size of my sample ?
Is percentage from the quantity recived ?

Best regards
God bless you



Thank you for your ansver

Hello,

To determine the sample size is really a challege job ! That is mostly related what products you make, quality level of the receiving material, importance of the characteristics to be inspected, difficulties and cost of the inspection etc. Here are some hints from my experience:
- If it is a bulk raw material, you only need to take one sample( fixed weight or volume needed for the inspection) from the incoming bach or lot.
- If the quality level is low, you should take more samples which should be enough for conducting statistical analysis, which can the calulation of process capability such as Ppk. If the continuos receiving inspection result shows good/bad capability( less than 1.33 or greater than 1.67 for example), you should reduce/increase the sample size.
-You can use skip lot philosph depending on quality level.
- To make the sampling method simple and reasonable. You should understand if and why the sample size is to high or too low.
- Both 100% inpection and no-inspection ( but verify supplier inspection report ) is applicable.

Hope this help you to set up your own procedure and control leve.

Best Regards
Johnson Shao:bigwave: :bigwave:

Luciano,

I always prefer to apply ANSI Z1.4 for incoming sampling as it is based on statistical approach. It also helps me to avoid lot of customer queries. When I tell them that I apply ANSI Z1.4, they are comfortable (and definitely I am :D )

In my procedure, I have pasted the ANSI tables and an example to show how to select the total num ber of cartons and no. of units to be sampled.

Hello friends

In need some help to understand if I need AQL for incoming inspection or not for ISO 9001.
I am trying to implement ISO 9001 in the factory where I work, and I don't know what to do.
If I don't need AQL, how I will establish the appropriate sample for inspection.
If I need AQL, which is more proper.

Thank all of you very much.

ANSI Z1.4 is what most people use, even though it replaced MIL-STD-105 (almost to a tee).

There is no requirement in ISO9001:2000 requiring a Sample Plan. This is usually specified in the contractual document, under most conditions. In my opinion.

I use the Binomial or Poisson directly for sample size seelction.
One issue with using AQL plans is that they determine sample sizes based on the probability of accepting the stated defect (AQL) level. (and yes, I know I could use the LTPD...but I like things as simple and straigthforward as possible.

I always use "accept on 0, reject on 1".

given the defect level, p, that you want a high confidence level in detecting and the confidence level, P(detection), (the probability that you will detect a process that is 'p' defective or worse...)

the Binomial yields: n = natural log(1-P(Detection)) / natural log((1-p)

the Poisson yields: n = -natural log(1-P(detection)) / p

so if you want to catch a lot that is 0.5% defective 95% of the time
p=.005
P(Detection) = .95

n = 598 with the Binomial
n = 600 with the Poisson

Hello,

To determine the sample size is really a challege job ! That is mostly related what products you make, quality level of the receiving material, importance of the characteristics to be inspected, difficulties and cost of the inspection etc. Here are some hints from my experience:
- If it is a bulk raw material, you only need to take one sample( fixed weight or volume needed for the inspection) from the incoming bach or lot.
- If the quality level is low, you should take more samples which should be enough for conducting statistical analysis, which can the calulation of process capability such as Ppk. If the continuos receiving inspection result shows good/bad capability( less than 1.33 or greater than 1.67 for example), you should reduce/increase the sample size.
-You can use skip lot philosph depending on quality level.
- To make the sampling method simple and reasonable. You should understand if and why the sample size is to high or too low.
- Both 100% inpection and no-inspection ( but verify supplier inspection report ) is applicable.

Hope this help you to set up your own procedure and control leve.

Best Regards
Johnson Shao:bigwave: :bigwave:

Hi Johnson,

Thanks for your post. I have a better understanding about sampling inspection now.

Could you please kindly explain more on 'process capability such as Ppk'?

I'm newbie in this QA work and is currently cracking my head :frust: to determine sampling size of final inspection for product release. Our product is test kits for drug detection. Each batch of product is only about 20 test kits. The test kit is not-reusable after testing.

Thanks,
Sharon

Hi Sharon,

You can find many documents and templates in the "Post Attacments List" of this forum which explain process capability, PPk, Cpk

Here it is how CPK and PPK is calculated :

Cpk = min { (USL - Xbar) /3 sigma, (Xbar - LSL)/3 sigma}

Pp = (USL - LSL) / (6 Sigma)

Ppk = min {(USL - X bar)/3 Sigma, (X bar - LSL)/3 Sigma}

Where:
USL is the upper specification limmit
LSL is the lower specification limmit
X bar is the average value of the group of inspection data.
Sigma is the standard deviation of the group of the data.

There is also other calculation method depending on how is the data collected

Ppk in QS9000 means Preliminary Process Capability Index. It
should be calculated before Mass Production and based on limited product
quantity. Normally, it should be more than 1.67 because it's a short term
process capability which doesn't consider the long term variation. But, in
QS9000 3rd edition, there's no Compulsory Requirement that the Ppk must be more than 1.67. In QS9000 3rd edition, it states like Ppk/Cpk >=1.33.
Another one is in 6-Sigma. Ppk in 6-Sigma means Process Performance Index. It's a long term process capability covered the long term process variation and based on more product quantity. Generally, in 6-Sigma, the Ppk value is less than Cpk value.
Ppk：Overall performance capability of a process, see Cpk.
Cp：A widely used capability index for process capability studies. It may range in value from zero to infinity with a larger value indicating a more capable process. Six Sigma represents Cp of 2.0.

Hope it will not lead you more confused. But you can read some literatures to understand it.

Luciano,

From statistical theory, the sample size should be chosen according to the table which have been established in the national standard of many countries.

But as you may awared that it is not good for practical use. The concept of AQL does not reflect the philosphy of "zero defect".

You can keep the sampling size " simple and stupid". But the important thing is you should not accept any defect in receiving inspection. That means if you find one single defect during the inspection, you must sort or inspect the whole lot.

I would not suggest use percentage. You may use either "standard " method like regulated in ANSI Z1.4 , or fixed samle size.

Thank you very much for your reply. I just got a copy of the ANSI standard Z1.4 and Z1.9. The Z1.9 is actually an old version (1980), but I supposed it will be sufficient for me to understand some basic.

Anyway, I still not very sure about which standard to follow: Attributes or Variables? I supposed for our product which QC test are measure in mean, standard deviation & CV, the inspection by variables is the appropriate one. Am I right?

1.apperance, Use ANSI/ASQC Z1.4 Single Sampling Plan for General Inspection Level I AQL: 0.25(critical), 1.0(major), 2.5(minor).
2.packing, IQC inspector draws 13 reels (bag, roll, box, etc packing unit) for checking inner conformance , if receipt packing is less than 13 reels(bag, roll, box, etc packing unit), IQC should check all the receipt. Accept=0, Rej=1
3.function,Use ANSI/ASQC Z1.4 Single Sampling Plan for Special Inspection, LEVELS-3, AQL at 1.0.

Thank you very much .
There is another way to evaluate by sampling without AQL my incomings part ?
Usualy a recive a plastic raw material (PP, PE-LD, PE-HD, ABS....); colour pigments, metal pipes.
How can I establish the corect size of the sample ?
For me it's Ok tu use AQL, but if it's not necessary I don't want to complicate the sistem (we are not a big factory approximately 100 peoples, ) but allso I want to assure the quality of incomings
Many, many thanks.
God bless you

Is it mandatory to have inspection at incoming stage? if we verify only suppliers' inspection report,it will be accepted by ISO auditor?

Is it mandatory to have inspection at incoming stage? if we verify only suppliers' inspection report,it will be accepted by ISO auditor?

If that is your acceptance criteria, you define your acceptance criteria and if it is AQL's it is up to you.:notme:

Is it mandatory to have inspection at incoming stage? if we verify only suppliers' inspection report,it will be accepted by ISO auditor?[/QUOTE]

yes, it's a mandatory requirement which any purchased material must be checked in IQC station,only passed mateial can be allowed to warehouse,theese checking method is yourself definition in your organization, such as, verify supplier checking report, do what you wrote in your QMS.

it is not mandatory in ISO9000 to have incoming inspection. You need to specify how you ensure the quality of yoru incoming material. YOU specify this.

UNLESS there is a specific Customer requirement to do incoming inspection.

Luciano,

Are you talking about plastic resin? If the sources are from branded companies, then you can look at the materials specification. Some properties maybe very critical to your processes such as melt flow index.

If you are worry about strength, you may want to mold some of them into ASTM standard to test the properties.

Resin usually come in batches like 25kg and in pellet forms.

Hi,

Its not ISO or TS company rule to followed AQL, LTPD,AOQ or related terms.

Why we are following AQL.......

The answer is while doing sampling inspection, 1) we have to do certain risk & its logical while doing that. 2) We have to accept that theat while inspection ( Risks- Producer as well as customer )