Six Sigma was invented to improve manufacturing processes and it aims to improve the process output through various techniques. It involves the removal of errors and the reduction of the variable quotient in business and manufacturing processes.
6 Sigma levels represent the reliability of the process, higher means the process is reliable and working in good condition. Let us assume if Six Sigma level one means 61% of the parts produced or service rendered by the process are defective, which further means only .00034 percent of the parts are defective. It is calculated by the number of defects per million opportunities (DPMO).
The sigma level provides the metrics to understand the capability of the process or an organization to meet the customer requirements.
When DPMO is calculated?
- DPMO is calculated in the measure phase of the DMAIC Process, DMAIC Define, Measure, Analyze, Improve, and Control. It refers to a data-driven quality strategy for improving processes.
- DPMO may be used throughout the DMAIC process as per the questions raised.
- It is calculated to improve the Sigma phase.
How to calculate DPMO in six sigma?
DPMO can be calculated by gathering the information. First, we have to collect the data for the number of units produced. The number of defect opportunities per unit, and the number of defects.
The below mentioned formula to calculate the number of defects in the process per million opportunities;
DPMO is number of Defects x 1,000,000((Number of Defect Opportunities/Unit) x Number of Units)
Let’s brief it through the example of a Laptop manufacturer who wants to calculate the 6 Sigma of its manufacturing process. For two months, the manufacturer makes 83,934 laptops and during the test phase, 3,432 laptops were rejected.
From the above mentioned formula, we get defects = 3432 Opportunities = 83934 Defect Opportunities per unit = 9 DPMO = 5111.158768
You can use the table below to find out the level for respective DPMO value:
Six Sigma Level DPMO 1 690,000 2 308,000 3 66,800 4 6,210 5 320 6 3.4 For the example given above, DPMO of 5,111 is less than 6,210 and greater than 320. Hence, it results in a 6 Sigma level four designation.
Six Sigma calculations are all about statistical analysis and report generation through which anyone can understand the process flaws and requirements. Through the above-mentioned examples, you can calculate Six Sigma to a wider level.