Six Sigma is a methodology designed to control variations that result in defects. In Six Sigma a defect is any thing that is outside customer specification. The Six Sigma method was pioneered by Bill Smith of Motorola. To qualify for Six Sigma a system must demonstrate a defect level of 3.4 defects per million opportunities (DPMO). While originally pioneered by Motorola, it has been adopted by many industries, hospitals and even by the US Navy.
The basic objective of the Six Sigma process is to achieve improvement in process techniques and reduce variation by applying Six Sigma improvement projects. The Six Sigma method uses two techniques in this regard. They are the DMAIC and the DMADV techniques.
DMAIC is the acronym for define, measure, analyze, improve and control. This method is used to improve an existing process.
In the define stage the goals for process improvement are defined. These goals should be consistent with the demands of the customer and the overall strategy of the enterprise. The next stage, the measure stage involves defining baseline measurement on which future improvements can be compared.
The subject process is mapped and measured and the necessary process data is collected. In the “analyze” stage the relationship between the different factors involved in the process is studied and identified. In the “improve” stage the process is optimized using analytical techniques. In the control stage, the process capability is established using pilot runs. The production is started and continuous measurement of quality using instituted control mechanisms that seek to correct the variances before they become defects.
DMADV is the acronym for define, measure, analyze, design, verify. This method is used to design new process which result in a mature and defect free performance.
In the “define” stage the goals of the design activity are defined in consistency with the expectations of the customer and the larger objectives of the enterprise. In the “measure” stage production process capability, risk assessment, product capabilities are defined. In the “analyze” stage the design alternatives are created. The design capability is evaluated to select the best design. In the “design” stage, simulations are carried out to develop, optimize and create a plan for design verification. In the “verify” stage, the design is verified, pilot runs are setup, the production process is implemented and handed over to the process owners.
The Six Sigma methodology has identified five key roles in the process of implementation. They are
1. Executive leadership: This usually includes the CEO and members of the management team. The responsibility of creating a vision for the Six Sigma process falls on them. In addition, they are expected to provide the power and resources for people in other roles and encourage them to study new ideas.
2. Champions: They are concerned with the implementation of the Six Sigma process across the organization in a systematic manner. They are usually drawn from the upper management.
3. Master Black Belts: These are identified by the champions. Their primary responsibility is the Six Sigma process and they devote their entire time to it. They ensure the development of Six Sigma throughout the various departments and functions.
4. Black belts: They function under the master black belts and enforce the methodology of Six Sigma to particular projects. They primarily involve themselves in the execution of Six Sigma process.
5. Green belts: These are employees who are involved in Six Sigma implementation along with their routine duties.