Defects, Defectives & DPMO

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Hi readers! Today we will discuss about the Defects, defectives, and DPMO. These words are mainly used in Six Sigma and other TQM initiatives. 

Defects – An output of the process that does not meet a defined specification.

Defectives – A product that contains at least one defect.

DPMO – It stands for Defect Per Million Opportunity. It is metric system used in Six sigma and other TQM initiatives to map rejection or waste etc. If we can not measure it, we can not improve it. Metrics help us to understand where we actually stand. It is used in manufacturing industries, Service Industries etc.

Let us understand it with a simple example.  Suppose, ABC is a company that manufactures domestic bucket.

  There is a process called molding, by which plastic bucket is molded.

               After molding process, Quality inspector checks (say) 6 nos. of Critical specifications of bucket and if all the specifications are met then it is considered to be an OK product otherwise it will be treated as Not good (NG) Product.

The 6 critical specifications are mentioned below :-

  1. Aesthetic view
  2. Sharp Edge at handle
  3. Shrinkage
  4. Feather
  5. Stress mark
  6. Dis color

If an inspector while inspecting a bucket finds a sharp corner present at handle which can hurt the finger when it will be used, then this is called DEFECT. Specification requirement was that sharp edge should not be present at the handle but it was found. Inspector also found some shrinkage on further investigation, so now as two defects are found, it will be considered as defective.

Opportunity – Number of place/area where defect can occur. In the previous example there was 6 critical specifications where defect can occur. So, in that case number of opportunities is Six.

Let us calculate the DPMO of previous example.

Suppose 10 Nos of buckets were inspected by the inspector.   Say number of defects found is 3 in all the 10 nos. of buckets.

Here opportunity = 10*6 = 60

DPMO = (total no of defects/ Total opportunity)* 10^6

             = 3/60 *10^6 =50000 DPMO

Lets do one more example. Suppose MXP is a biscuit manufacturing company.

Here, there is 3 critical parameters that need to be checked.

  1. Overall shape of the biscuit
  2. Weight of the biscuit
  3. Crunchiness

Number of biscuits = say 100

Number of defects found = 5

So DMPO =?

Opportunity = 100* 3 = 300

DPMO = (total no of defects/ Total opportunity)* 10^6

             = (3/300)*10^6

             = 10000 DPMO

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