Overview of Six Sigma
Annamalai C
Lean Six Sigma Trainer for Global Participants |Lean Six Sigma Consultant | Lean Consultant | 40+ Years Experience Driving Operational & Manufacturing Excellence | Transformational Change
Six Sigma and Variation:
??????? Variation is simply a deviation from expectation.
??????? Variability is inevitable in any process
??????? This variation in the output is caused by the variations in the inputs and the process conditions
??????? The variation in the process is too large sometimes that we produce defective – products not at the acceptable level
??????? Six Sigma focuses on reducing variations in the inputs and process conditions to improve the processes and get consistent quality of products and services
Variation is simply a deviation from the expectations/targets or standards. We are aware that Variability in a process is inevitable. Be it a manufacturing process, a service-related process, a software-related process, or a natural process, we can always see variations. In our processes, we find that some days they are running in their best conditions and we get the best results in terms of productivity/quality/defect rate. On some other days we find that without any visible reasons, the results are bad. Variations in the outputs are a major concern for all of us. We should realize that the variations in production are caused by the variations in the inputs and the process conditions. Sometimes the variation is too large that the processes start producing defective products or services that are not acceptable to customers. Though the process's variation can never be fully eliminated, it can be reduced. Six Sigma methodology focuses on reducing the variation in the outputs by reducing the variations in the inputs and the process conditions so that we always get consistent quality of products and services.
We can see the variation in the process before and after doing a Six Sigma project. The project was done to reduce the % rejections in a process. Before doing the Six Sigma project, the average rejection was around 21% and the variation in the rejection was very high – from 15% to 25%. After doing the Six Sigma project, we see a drastic reduction in the average rejection – from 21% to around 8%. Also, the variation is reduced significantly to vary from 6% to 10%. That is the beauty of Six Sigma methodology. It helps in improving the metrics taken up for improvement by identifying the critical inputs and process conditions contributing to variability in outputs and reducing it to a very narrow range.