Six Sigma

Six Sigma process improvement is a rigorous procedure through a series of steps summarized by the acronym DMAIC. The focus of Six Sigma is the Customer. The Customer is the receiver or user of the output of the process. Customers can be internal or external to the organization. Six Sigma defines and quantifies customer requirements, then suggests and implements changes to the process to improve the quality of the product or service.

Each step has its own framework and many tools that can be utilized by the improvement team. The specific tools used in each step depends on the data gathered so far and the judgment of the improvement team. As more is learned at each step about the process and the product, several iterations may be necessary at each DMAIC step before the team is ready to move forward. It may take many weeks of hard work to accomplish each step. It is beyond this blog page to fully describe the components of each step. A basic definition of the steps are:

Define - Define the problem and the scope of the process under study for improvement.

Measure - Measure the output of the process and establish benchmarks to understand if the process meets customer requirements and to provide a baseline to evaluate improvements. Customer requirements are also called Critical to Quality Characteristics (CTQs). Also, measure key parameters of inputs and key steps within the process to enable the team to understand the problem and identify areas for improvement.

Analyze - Figure out what the data is telling you about the process and where improvements should be made. Often the data tells the team problems with the process are not the ones suspected during the Measure step. This can often mean additional data is necessary before the analysis step can be completed.

Improve - Implement the changed sub processes decided upon by the improvement team. Then measure the the improved process to see if quality of the product has improved to the level desired and is in control. If it has not, make additional or alternate changes to the process and impliment and measure again.

Control - Make sure the process remains centered, in control and within tolerances. Hand the improved process over to the process owner. Establish procedures for maintaining the improved process and a system for measuring the output of the process to catch out of tolerance conditions.

Sometimes while on the DMAIC path somewhere between Define and Analyze the team comes to the conclusion that the process simply cannot be improved sufficiently to produce the desired output with the required level of defects or at a reasonable cost. At this point the team will examine replacing the process with a new one. The team will then use a slightly different process. Often this is called Design for Six Sigma (DFSS). As Six Sigma is an evolving process with different practioners coining their own terms, there are several acronyms to describe it. The first is DMADV Define, Measure, Analyze, Verify. Another is IDOV Identify, Define, Optimize, Verify..