iSixSigma

Defect

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  • #34222

    Ravi kumar
    Participant

    Hi,
    My name is Ravi Kumar and I work for a Polyester manufacturing company in India. I am completely new to this Six Sigma concept. We are an ISO 9001 company and follow the system of segregation and downgradation of product that is not matching with our quality norms.
    My question is How do I define a Defect? 
    (a) Defect is the product that does not perform at customer end (or)
    (b) Product that is made and got downgraded as it was not meeting to Quality Norms.
    Please educate me.
    Thanks,
    Ravi
     

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    #93982

    Divdar
    Participant

    A defect should be defined by your customer.  So, typically, an actually defect would be one that does not perform at the customer end.  However, there are several factors here.  First, you have both internal and external customers.  An external customer is one who actually buys the end product.  An internal customer could be the next process step in the production line.  Second, you have both the Y and the X to deal with.  Y = (f)X.  Your Y is what your customer (either external or internal) is concerned about.  Your X is what you measure to ensure the Y is in compliance.  So, a product that does not perform at customer end (does not meet Y) is a defect, but so is a product that doesn’t pass the quality check (X) and is downgraded, since if it would have passed, it would have been a defect at the customer. 
    This is probably confusing for such a simple question.  Sorry.  If you are working on a project, start by identifying the customer and determining what is a defect to them (voice of the customer).

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    #94014

    SSS
    Member

    Hi Ravi,
    A defect is anything that does not meet customers’ requirements. Your two questions are basically the same because quality norms are set by the customer’s requirements (or customer’s end, as you call it). 

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    #94021

    indresh
    Participant

    Dear Ravi,
    slight variation from the views expressed here
    Sometimes we get too customer oriented and forget what the goals of the comapany are….giving a typical example, lets assume the company is turning around its brand image from being a producer of a mass product to one targeting an exclusive customer segment or wants to provide better product to the customer in the future to achieve some of its defined goals.
    in your case have the upper specification limits whichever is higher between the customer and the company quality policy but keep the lower specification as that of the customer
    in this case there will be the exact measure of classification of defect and non defect
    hope it suffice
    rgds,
    indresh
     

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    #94025

    Sridhar
    Member

    Hi Ravi:
    A slighly different twist. Both your definitions are acceptable…it all depends at what level you are doing the project at.  At a system level, a defect would be a failed product at the customer. When you do a CTQ flowdown, you could find that for a subsystem level project line-defects would be the defects you want to fix.
    I hope this helps
    Cheers
    Sridhar

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    #94026

    Elizabeth
    Participant

    Six sigma begins with identifying who the customers are for the problem you are tackling.  These can be external or internal eg the purchasers of your product or the business team.  Do not get stuck in the mindset that only people you sell to are customers.  There must be a flow from VOC to CTQ’s to Y, otherwise how do you know you are tackling the “right” thing?  After defining Y you set the performance standard / standards that must be achieved to met customer expectations.  The performance standard work will tell you what your defects are.
    In short:  You don’t define defects, the customers for the product of the process you are improving do.

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    #94041

    Brendan
    Participant

    Both your definitions are correct. A defect occurs when a quality parameter falls outside its intended level such that a product does not perform as required by the customer.

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    #94046

    Ron
    Member

    This question has been round the quality world without resolution for many years.:
    Two schools of thought: 1) Meets specification requirements, 2)Fitness for use.
    I prefer the meets drawing requirement approach as most frontline personnel are not trained well enough to assure fitness for use.
    For example: if a customer is promised a delivery by Thursday and they receive it on Friday that is a failure to meet specification. However is the customer did not care if they received the goods until Monday you have still met the fitness for use characteristic.
    They key here is to be able to set up a data collection system that can assess the fact that something was defective. So compliance to specification is always the best measure as it will always be the most stringent and easily measured quality.

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    #94050

    Mikel
    Member

    A defect is any use of resource over the minimum required to do the job right.
    So simple.

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    #94052

    Anish Patani
    Participant

    The goal of Six Sigma is to

    meet the customers need
    to ensure maximum profitability.
    Offering a better quality product to a customer than what he needs could be a good thing, but this should not happen at increased cost.
    It might not be a bad idea to have tighter specification limits than what your customer has asked for, but the consequence of that should not be impacting the customer in anyway.

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    #94061

    Anonymous
    Participant

    I personally like Juran’s definition of a defect.
     

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    #94075

    Luis
    Participant

    Ravi, at this time you have many opinions and definitions around your question. Maybe this other one could be useful in your searching of a one definition of defect. Defect is a deviation between should and actual. Should = Standard, norm, procedure, specification – set and accepted by all parts involved. Actual = Performance observed during the analysis. If Should is different to Actual a deviation is present and you have a defect.
    Regards

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    #94093

    Vargas
    Member

    But you did not write what is your product, there might be some criteria as to when you reject your product. If the number of defects are > “x” or may be even if there is one single defect. If it is so then apply DMAIC to reduce the number of defectives first and then to reduce the number of defects, based on the Pareto analysis. Since you said your company is a ISO 9001 company surely you might be collecting the data regarding the categories of defects and analyzing them.
    Thanks
    Srini

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    #94098

    Y M Joshi
    Member

    Dear Ravi
    Defect in  simplest and precise terms is the Negative Gap between the measure of the quality parameter or quality characteristic actually measured/observed  and that specified on the drawing or plan. If the gap is positive it may result in Customer Delight i e customer gets more than his expectations.
    It may happen that the product perfectly passes the quality check since it meets the planned specifications but fails at customer end. In such case the product is not really defective but the quality planning process is defective since it means that the customer needs are not correctly transformed into product specs.
    Downgraded product is certainly defective because it doesn’t meet specs and accepted under deviation. Such product could satisfy customer need and in that larger and broader sense may not be defective.e g a bent footboard of a vehicle indicates defect but the customer may not notice it or gets affected.. Therefore defect is viewed by quality specialists as deficiencies in the context of specs and not in the context of customer needs because ideally customer needs are supposed to be converted to product specs at the planning stage itself.by the design specialist. The quality specialist ,most of the time may not be aware of the customer needs. His job is to
    Regards
     
    Y M JOSHI

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    #94108

    Ron
    Member

    A discussion of the difference between defects and defectives seems to be in order here.
    A defect can be just about any anomalous condition that may occur in a product. As an example in paint finish a certain amount of anomalies can exist and still be considered an acceptable paint job.
    So to your question you first must define these criteria.

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    #98851

    ALEK DE
    Participant

    Any non conformance to specification is a defect.
    A product having having one or more defect is called defective. Say you are purchasing a T.V. set & volume knob and brightness knoba are not working. So you have two defects & the set is a defective one.
    Non conformance is always w.r.t specification , what it is deemed to have or perform.
    Thanks
    Alek
     

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