Is defect the same as nonconformity?

Defects adversely affect the functionality of the product; indeed the defective product may be dangerous. A product’s nonconformity is a failure of a characteristic to meet a requirement. Defective products are therefore more serious than other types of product nonconformity. The gap between the two (defect and nonconformity) is wasteful but a margin of safety is necessary because designers and customers seek assurance of safety, reliability and durability but both have limited information about the actual performance of materials, structures and subsystems in a wide variety of operating conditions.

Surely, because of these unknowns, we have to treat product nonconformity as if it were a defect? Therefore, defect and nonconformity may differ but we treat them the same way in that they must be corrected and that we should learn from them to improve our management systems.

In the continuum from an outcome being defective to perfect, we could usefully think along the following lines:

1. Defective – outcomes may injure or kill someone
2. Nonconforming – outcomes fail to meet a requirement
3. Quality – outcomes fulfill customer requirements
4. Excellent – outcomes exceed the needs of customers
5. Perfect – an ideal many choose to pursue

Meanwhile it is reasonable to expect designers to continue to improve their processes and product specifications based on their understanding of the actual performance of materials, structures and subsystems. This knowledge can be used to close the gap between defect and nonconformity.

Yes, designers must also address service quality or the customer’s feelings. Customer feelings are among the needs translated by designers into product requirements. Consequently, they appear in the product specification not as customer feelings but as product characteristics. We may prefer our tea served with love. The designer knows this but the service specification remains silent on this point so as not to sully the love characteristic of the service by specifying “serve with love”. This is why training is the key to excellent customer service. Designing the service part of the product remains an intriguing area of research. Of course, we continually learn more about product design and delivery by listening to the customer’s perceptions about how well their needs were fulfilled.

Differentiating clearly between an acceptance criterion (a requirement) and a blemish or deviation from perfection remains a difficult quest but we are on the other side of that continuum when we are talking about the difference between a defect and a nonconformity. From an engineering or design point of view, specifying the requirements that enable everyone to uniformly differentiate between 1, 2 and 3 are seen as the most important. Between 3 and 4 we have a point where customer needs become their new requirements. Some companies, such as Apple, anticipate or stimulate this transition point from hidden needs to requirements that drive customers to buy their products better than most. This may be due to the designers being very close to, if not the same as, the more futuristic customers.

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One Response to “Is defect the same as nonconformity?”

  1. Darrell Says:

    It’s an amazing article for all the online people; they will take advantage from it I am sure.

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