Six Sigma is a continues improvement process which strives to achieve zero defect production. It exists since the middle of 19th century and improving continuously. It was invented by Mikel Harry when he was working at Motorola to minimize the cost resulting from the poor quality of product and then used successfully by other organizations such as GE. Six Sigma is a customer oriented process and it works toward the customer satisfaction and process improvement.
The word ‘Sigma’ indicates the deviation from the ultimate aim of defect-free production. It determines the process performance. During the process, the defects are measured, the root causes which lead to defects are identified and eliminated. The Six Sigma is said to be achieved when the process achieves the accuracy of producing less than 3.4 defects per million opportunities. Here, the defect is defined as anything outside the customer specifications and opportunity is any chance of a defect in production.
Six Sigma allows us to compare or differentiate between different processes in company with the help of the same parameter called DPMO (defects per million opportunities). It helps to develop an atmosphere which encourages continues improvement 2.
Six Sigma consists of two main processes, DMAIC and DMADV, each consist of five phases.
1.1 DMAIC (Define, Measure, Analyze, Improve and Control)
DMAIC is mainly used for existing processes in a company. Many of the Six Sigma practitioners use this methodology when the process is not able to meet the customer expectations.
It is the first step of Six Sigma process. This phase includes the formation of a team. The leader creates a clear view of the end goals and customer specifications. They can be internal or external.
During this step, the team measures the current performance of the process. This is done by collecting the complete data related to the process. This helps in determining the behavior and possible root causes of the defects.
The effectiveness of this step is more dependent on the quality of the data collected. During this phase, the team combines the different sets of data and additional data available. Then the data is reviewed to find out the potential root cause of the defects. Also, the data analysis is carried out in efforts to detect wastage of resources.
This is part of solution phase. After determining the major factors behind the defects and wastage of resources, the brainstorming is done to find out ways to eliminate these factors. It includes collecting different ideas and forming a structured pathway to implement these ideas. The process is improved by eliminating the defects at the end of this phase.
The control process is more about maintaining the newly achieved improvements. The team creates a framework which should be practiced in presence and future to sustain these improvements and pass it to the employees.
1.2 DMADV (Define, Measure, Analyze, design and Verify)
DMADV is used for designing a new process or redesigning the existing process. This methodology varies according to the business, industry and culture. It is also called as DFSS (Design for six sigma).
This phase works the same way as in DMAIC methodology. As it designs the new process, it identifies the customer and their specifications. The project goals are decided according to the customer specifications and made clear to the team.
During this phase, the data regarding the customer specifications and benchmark processes in different competitor industries is collected.
This process involves complete analysis of the data related to customer and the benchmark processes. The brainstorming is done to find out different ways to meet the customer specifications. Different ideas or process options are developed.
A complete new process is developed to meet the customer specifications. During this phase, different process options are tested, and the process is designed.
It is the last phase of DMADV. This phase includes the implementation of newly designed process and verifying its performance. Its effectiveness is judged based on extending up to which it meets the customer specifications. New statistical tools are used to optimize the performance of the process.
Figure 2.1. Flowchart of six sigma implementation.
Six Sigma is a customer oriented process. The ultimate aim is to meet customer specifications. It eliminates the defects in a process which result in improvement in quality standards of production. This also reduces the wastage of resources. All this adds up to the financial profit of the company. Hence, the results of Six Sigma implementation can be seen financially.
Six Sigma is a preventive method which eliminates the root cause of defect rather than just solving the problem temporarily. It is applicable to all type of business processes irrespective of type of the business.
It requires skilled workers as high training is required to implement Six Sigma within the company. Many of the small business companies cannot afford such training. As it is applicable to all processes involved within the organization, it can result into bureaucracy and kill the creativity. The measures which are more suitable for a company, but those can cause slight defect are ignored and more extreme-level measures are applied within the company in order to achieve the high goals set by the Six Sigma. 3