Six Sigma Explained

Quality Process

Six Sigma is a systematic and organized method for improving processes, new products, and developing services. It is based on the radical reduction in the defect rate in order to meet the Customer’s requirements using statistical and scientific arguments.

The Six-Sigma methodology, as a measurement standard, has its roots in Carl Frederick Gaus’ (1777–1855) concept of the normal curve. However, as a standard for measuring product quality variation, it has emerged since the 1920s, when Walter Shewhart demonstrated that a process with quality variation greater than or equal to 3σ (three sigma, or three standard deviations) of its average would require correction of the process.

In the mid-1980s, Motorola began to consider samples of millions of units in its industrial process, which until then was traditionally measured in thousands. So she developed a new concept and created the Six-Sigma methodology (and a registered trademark).

The evaluation of results of the Six-Sigma methodology is not based on Quality Costs, it is based on project management and economic evaluation techniques, such as, for example, calculating the Present Value and calculating the Return on Investments.

The methodology consists of a group of stages applied depending on whether it is improving an existing process (DMAIC) or creating a new product or process design (DMADV).

Stage D — Formally define process objectives that are consistent with customer demand and company strategy.

Stage M — Define baseline measurements in the current process for future comparison. Map and measure the process in question and collect the necessary data. Identify CTQ requirements, production process capability, risk assessment, etc.

Stage A — Analyze to verify the relationship and causality of factors. What is the relationship? Are there other factors that have not been considered? Analyze by developing high-level design alternatives and evaluating their capabilities, aiming to select the best.

Stage I — Improve and optimize the process based on analysis, using techniques such as experimental design.

Stage C — Control the process with pilot tests, transition to Production, and then continuously measure the process to ensure that variations are corrected before they become defects.

Stage D — Design the process, developing it in detail, optimizing it and planning its verification. This step may require simulations.

Stage V — Verify the design, carry out pilot tests and implement production processes. This phase may also require simulations.

Six Sigma identifies five main functions for its successful implementation:

• Executive Leadership includes the CEO and other team members in senior management. They are responsible for establishing a vision for implementing Six-Sigma. They also delegate authority to other roles, with the freedom and resources to explore new ideas for important improvements.
• Champions are responsible for implementing Six-Sigma across the Organization in an integrated manner. Executive Leadership chooses them from senior management. Champions are also mentors to Black Belts.
• Master Black Belts act as internal experts for Six-Sigma within the Organization. They dedicate one hundred percent of their time to the process. They help Champions and guide Black Belts and Green Belts. Outside of the traditional rigor of statistics, your time is spent ensuring an integrated implementation of Six-Sigma across the company’s various functions and departments.
• Black Belts operate below Master Black Belts to apply the methodology to specific projects. They dedicate one hundred percent of their time to the process, but their primary focus is project execution, while Champions and Master Black Belts focus on identifying projects for Six-Sigma.
• Green Belts are employees who participate in the implementation of Six-Sigma alongside their other responsibilities in their work routines. They operate under the supervision of Black Belts and support them in achieving good overall results.

Six-Sigma brings financial benefits to the business. Its importance for quality assurance is considerable because in addition to allowing process improvements, its incorporation enables detailed understanding of processes, thus offering the ability to implement simple adjustments to complex changes.