Critical Tools of the Six Sigma Process

Last Updated October 24, 2019

Six Sigma principles have improved processes in the manufacturing, service, healthcare, government and nonprofit sectors for decades. The methodology can be successfully adapted to a wide variety of industries because Six Sigma uses tools that can be tailored to fit the needs of the organizations that use them.

No matter the industry, there are six tools that are essential for Six Sigma success. For those just starting out in Six Sigma, it is vital to becoming familiar with the following essential tools.

Project Charter – The first step of the first stage of the DMAIC cycle is for the team to create a project charter that defines what the project is and who will be responsible for specific tasks. The charter also identifies which process the team will be improving, along with the project’s objective. This typically builds team cohesion and a sense of purpose.

The charter also contains a business case that justifies the need for the project and estimates its potential financial benefits.

Process Map – This tool uses a detailed flow chart to display the current production process in color-coded symbols. The act of creating this map gives the project team a better understanding of how the process works. Once the process is thoroughly displayed on a map, team members have a common point of reference for suggesting changes and improvements in workflow.

The process map not only displays the current process but can be rearranged to display the improved process as well.

Pareto Chart – Separating the “significant few” from the “trivial many” helps project teams identify where to find the greatest potential for improvement. A Pareto Chart helps teams see where problems and opportunities for improvement lie at a glance.

The Pareto Chart plots the problem categories on the horizontal line of a graph in descending order from left to right. It lists the reported number of problem occurrences on the vertical line. The problem categories with the longest bars on the graphs represent the areas of greatest potential improvement.

Failure mode and Effects Analysis (FMEA) – FMEA is a tool used to evaluate a process to identify where and how it might fail, and to calculate the relative impact of different types of failures. To make this assessment, each potential failure is given a risk priority number based on three factors. Each factor is rated on a 10-point scale.

• Occurrence rating – Represented by O, this measures the probability of the failure occurring.
• Detection rating – Represented by D, measures how well the controls can detect the error before it impacts the customer.
• Severity rating – Represented by S, it measures how severe the failure is.

S x O x D yields a risk priority number that helps rank potential failures in the order of their seriousness.

Design of Experiments – Helps identify problems in the process that cause defects in the product or service. The project team manipulates factors in the production process to measure their impact on the desired result.

Control Chart – This tool helps the project team know when to modify the process and when to leave it alone. The control chart does so by separating common cause variation, which is random and uncontrollable, from special cause variation that can be corrected.

A project team’s choice of Six Sigma tools is not limited to those listed above. Six Sigma has a vast number of tools that, like these, can be adapted to improve processes in a number of fields and industries. However, a Six Sigma project that uses these tools correctly can greatly increase the potential for success.