Classification of Major & Minor Defects

R

rilakuma1121

#1
Hello , I am an undergraduate student studying quality engineering.
I m recently studying a phenomenon about the classification of major and minor defects. Normally in practice, people will set a smaller AQL for major defects and a larger defects for minor defects .
But in some situation , there will be an over-critical in minor defects which is saying the minor defects into major defects . Is it really happen in reality? How can you minimize this happen ?
I really need the experiences from all of you. Thank you very much
 
Elsmar Forum Sponsor

TWA - not the airline

Trusted Information Resource
#2
Not exactly sure if I really understood the question the way you meant it, but here's my take on this:
Generally you classify by the risk associated with the defect (or failure modes based on the defect). Risk is the combination of hazard and probability of occurence. Typically harm to persons leads to high risk classifications even with low probabilities, while not so critical hazards (could also be damage to your bussiness...) only become high risk when they happen quite often...
If you know your risk then in a second step you define you control measures, like e.g. AQL inspection. But inspection may only be a small part of the control effort. If you for example have a rare defect that is highly critical because the hazard is death of a person then maybe you'd validate the process rather than do inspection (which probably would mean doing 100% inspection rather than defining an AQL...) Or you may have a defect that is not critical but causes trouble with your customer because of the high incidence then maybe for some time this defect gets more attention because of the business risk or as part of the effort to determine the root cause and find a preventive action. So there are reasons why you would not simply choose AQL based on a major/minor classification.
 

John Broomfield

Staff member
Super Moderator
#3
Also, compare the definition of defect with the definition of nonconformity and you will see that a defect already is a major nonconformity.
 

Jim Wynne

Staff member
Admin
#4
Also, compare the definition of defect with the definition of nonconformity and you will see that a defect already is a major nonconformity.
For the purposes of this discussion, "defect" and "nonconformity" are essentially synonymous. The question is about how to classify defects (nonconformities). There are degrees of severity and significance, and understanding how risk is evaluated and mitigated is an important topic that doesn't lend it self to simple answers.
 
R

rilakuma1121

#5
Actually, what I m trying to ask is , is it a common problem of over-critical minor defects(non conformity) to major defects(non conformity).

For example, after the sampling inspection, a crack is found on the product.
the producer saying the crack should be a minor nonconformity so it should be accepted while the costumer will say "oh no, this is a major conformity, i cannot re-sale the product with such problems , this product is rejected."

How will this situation affect the acceptance of probability of the lot? the producer risk must increase because the AQL of major non-conformity is smaller which means smaller number non-conformity items can be tolerated. So if there is a proportion of minor defects being over-critical as major defects, the Pa should be affected.

Furthermore, how is the manufacture usually deal with this situation with the customer? Should this be stated in the contract with a detail information saying that under which situation it is a major nonconformity or minor nonconformity.
 

John Broomfield

Staff member
Super Moderator
#6
rilakuma1121,

You need first to agree with the customer the product acceptance criteria and these criteria become the basis for your contract.

That way the price of removing blemishes can be provide the customer with a reality check unless, of course, your competitor offers a higher standard for the same price.

Have you agreed a price before agreeing the acceptance criteria?

John
 
R

rilakuma1121

#7
rilakuma1121,

You need first to agree with the customer the product acceptance criteria and these criteria become the basis for your contract.

That way the price of removing blemishes can be provide the customer with a reality check unless, of course, your competitor offers a higher standard for the same price.

Have you agreed a price before agreeing the acceptance criteria?

John
How to set the acceptance criteria can minimize the chance of having this kind of argument? Since every situation may have difference variance, such as the length of a crack, how large the crack should be can regarded as major conformity? Should these things be clearly stated and discussed in the contact?

Furthermore what do you mean the price of removing blemishes?
 

Jim Wynne

Staff member
Admin
#8
Hello , I am an undergraduate student studying quality engineering.
I m recently studying a phenomenon about the classification of major and minor defects. Normally in practice, people will set a smaller AQL for major defects and a larger defects for minor defects .
But in some situation , there will be an over-critical in minor defects which is saying the minor defects into major defects . Is it really happen in reality? How can you minimize this happen ?
I really need the experiences from all of you. Thank you very much
If a single lot is being inspected in accordance with a given sampling plan, the sample quantity size will generally be based on the most significant risks. In other words, the sampling plan for a given product should be based on the likelihood of detecting defects classifed as "major," if there are such classifications.

The "major" and "minor" classifications are usually tied to what happens after the defects are discovered. For example, it might be decided that an occurrence of a single major defect results in rejection and possibly sorting of an entire lot, while discovery of a minor defect might be considered acceptable under defined criteria for lot acceptance.

A given lot with a relatively large number of minor defects might be treated the same way as a lot with a single major defect, depending on circumstances.
 

Jim Wynne

Staff member
Admin
#9
How to set the acceptance criteria can minimize the chance of having this kind of argument? Since every situation may have difference variance, such as the length of a crack, how large the crack should be can regarded as major conformity? Should these things be clearly stated and discussed in the contact?
There are few situations where all of the possible contingencies are anticipated. The idea is for the supplier (producer) to review the requirements and determine whether or not performing the work is feasible in terms of manufacturing capability (among other things). If there are ambiguities, they should be reconciled to the extent possible prior to accepting the contract and commencing the work. In your hypothetical, if an engineering drawing said "no cracks," and the definition of "crack" isn't clear, the requirement should be defined such that objective evaluation is possible before the contract is accepted.

In theory, a customer can't unilaterally change acceptance criteria once the contract is finalized. I say "in theory" because in actual practice it does happen, and the extent to which it's tolerated by a supplier depends on the risk presented by making an unreasonable customer unhappy. Sometimes a supplier has to stand his ground, and in other instances a decision might be made to acquiesce in order to keep the peace.
 

John Broomfield

Staff member
Super Moderator
#10
How to set the acceptance criteria can minimize the chance of having this kind of argument? Since every situation may have difference variance, such as the length of a crack, how large the crack should be can regarded as major conformity? Should these things be clearly stated and discussed in the contact?

Furthermore what do you mean the price of removing blemishes?
rilakuma1121,

A blemish is a deviation from perfection that is acceptable to the customer. The boundary between blemish and defect is where you will agree product acceptance criteria. Any deviation from the acceptance criteria would be a product nonconformity.

Normally, the design process translates customer needs and product performance requirements into product acceptance criteria. These criteria must be agreed before quoting a price.

Yes, they are agreed by using samples and photographic standards.

Agreeing a price only for the customer to squeeze you on their personal understanding of quality makes no sense. It stops you from designing your processes to result in acceptable products.

It reduces quality control to sorting what the customer likes from what the customer does not like on any particular day.

As you can see it is a road to ruin.

John
 
Last edited:
Thread starter Similar threads Forum Replies Date
V Audit CAR Classification definitions - Major, Minor, or Observation General Auditing Discussions 2
K SCAR (Supplier Corrective Action Request) Major and Minor Classification Nonconformance and Corrective Action 4
A FDA Class Classification for a cabinet 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 1
dinaroxentool Question about FDA Classification of a Device 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 3
N What is our product classification? (Does Unclassified classification still exists) Other US Medical Device Regulations 14
nadhar2 Classification of Action Items Misc. Quality Assurance and Business Systems Related Topics 3
A Class medical device (MDD) - Classification help EU Medical Device Regulations 1
D IEC 62304 Risk Classification - With and without hardware control IEC 62304 - Medical Device Software Life Cycle Processes 2
M Classification of Clean Rooms Other Medical Device Related Standards 9
A ISO 10993-7:2008/ Amd.1:2019 - Classification of special populations Other Medical Device Related Standards 1
DuncanGibbons Classification of aerospace parts depending on their risk and criticality etc. Federal Aviation Administration (FAA) Standards and Requirements 3
M Barrier cream classification EU Medical Device Regulations 2
N Medical Device Classification under MDR - Rule 21 EU Medical Device Regulations 11
M Risk Classification For Supplier - Clinical Research Organisation (CRO) Supply Chain Security Management Systems 3
D Classification of Syringe (nozzle) of needle free injection system. EU Medical Device Regulations 8
S CE Mark - Classification Confusion EU Medical Device Regulations 12
S Medical Device Product Classification in South Korea Other Medical Device Regulations World-Wide 1
M Informational US FDA – Ear, Nose, and Throat Devices; Classification of the Self-Fitting Air-Conduction Hearing Aid Medical Device and FDA Regulations and Standards News 0
D MDR 2017/745 Classification Guide EU Medical Device Regulations 8
M Informational EU – Guidance on Qualification and Classification of Software in Regulation (EU) 2017/745 – MDR and Regulation (EU) 2017/746 – IVDR Medical Device and FDA Regulations and Standards News 2
dgrainger Informational MDCG 2019-11: Guidance on Qualification and Classification of Software in Regulation (EU) 2017/745 – MDR and Regulation (EU) 2017/746 – IVDR Medical Device and FDA Regulations and Standards News 0
M Informational EU MDR Classification Rule 11 – what??? Medical Device and FDA Regulations and Standards News 9
M Informational US FDA Final Guidance – Acceptance Review for De Novo Classification Requests Medical Device and FDA Regulations and Standards News 1
A Fire hazard classification - Clause in IEC 60601 about gauze and electricity ISO 14971 - Medical Device Risk Management 0
J MDR Annex VIII, Rule 6 Classification - Implication for lower risk CV products? CE Marking (Conformité Européene) / CB Scheme 3
A Device Classification - India CDCSO - How to classify the device? Other Medical Device Related Standards 1
B ASTM F2924-14 /ASTM F3001 - Room temperature classification criteria Other US Medical Device Regulations 0
M Informational EU – MANUAL ON BORDERLINE AND CLASSIFICATION IN THE COMMUNITY REGULATORY FRAMEWORK FOR MEDICAL DEVICES Version 1.22 (05-2019) Medical Device and FDA Regulations and Standards News 2
E Wristwatch Skin-proximal glucose sensor - Classification under MDR EU Medical Device Regulations 4
K MEDDEV 2.4/1 rev. 9 Classification EU Medical Device Regulations 1
M Informational USFDA – Medical Devices; Anesthesiology Devices; Classification of the Ventilatory Electrical Impedance Tomograph Medical Device and FDA Regulations and Standards News 0
N Medical Device Re-Classification EU Medical Device Regulations 2
B Class IIB Device - IEC 62304 Software Classification IEC 62304 - Medical Device Software Life Cycle Processes 13
C Suppliers re-classification from Critical to Significant or from Significant to Non-critical Supply Chain Security Management Systems 0
J Medical Device re-classification and marketing ISO 13485:2016 - Medical Device Quality Management Systems 13
M APQC PCF (Process Classification Framework) and ISO 9001 - Processes Based Approach ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 7
M Informational TGA – Several proposed changes to classification to better align with the EU MDR Medical Device and FDA Regulations and Standards News 0
N Medical Device Accessory Classification - Software as a Medical Device Other Medical Device Regulations World-Wide 5
G EU MDR 2017/745 Rule 11 interpretation - Re-classification of a Software as Medical Device Other Medical Device Related Standards 0
M Medical Device News Manual On Borderline And Classification In The Community Regulatory Framework For Medical Devices Medical Device and FDA Regulations and Standards News 0
M FDA News USFDA Final Rule – Medical Device Classification Procedures: Incorporating Food and Drug Administration Safety and Innovation Act Procedures Medical Device and FDA Regulations and Standards News 0
M FDA News The FDA Issues Final Rule on Medical Device Classification Procedures Medical Device and FDA Regulations and Standards News 0
K Biocompatibility classification for Lancet CE Marking (Conformité Européene) / CB Scheme 7
sagai Classification for compiler's runtime libraries IEC 62304 - Medical Device Software Life Cycle Processes 3
K Classification of IVF/ICSI devices (micromanipulator) in Mexico Other Medical Device Regulations World-Wide 0
M Medical Device News Medical Device Borderline and Classification Manual 1.20 - October 2018 EU Medical Device Regulations 0
H Classification of a device that uses an existing battery IEC 60601 - Medical Electrical Equipment Safety Standards Series 2
H Classification of a Class IIb Medical Device with 3 Components CE Marking (Conformité Européene) / CB Scheme 1
L Classification of Medical vs Wellness Devices Canada Medical Device Regulations 2
D Changing software classification via software - IEC 62304 IEC 62304 - Medical Device Software Life Cycle Processes 3
Similar threads


















































Top Bottom