What is Six Sigma?

In this Article

In this article you will learn…

• What is Six Sigma? A brief summary.
• The origins and development of Six Sigma.
• The five stages of a Six Sigma Project (D.M.A.I.C.)
• Other continuous improvement strategies.
• What is Lean Six Sigma?

Six Sigma — A Shared Business Improvement Strategy

Six Sigma is a continuous improvement strategy, it uses a set of tools to aid leadership and foster teamworking to make processes work better or faster or cheaper. I don’t usually like mission statements but that’s about as concise and simple as I can make it.

You would probably agree that you need a strategy for continuous improvement, if only to have a common approach and a common language in your business. When it comes to managing change, whether that be from the bottom up, lead by teams on the shop floor or in the office, or from the top down, implementing initiatives from management, it is imperative that everyone knows how to approach problem solving and how to work and pull together successfully.

Origins in, But Not Limited to Manufacturing

Six Sigma grew out of Motorola’s need to improve their semiconductor fabrication processes in the 1980s. These were typically low yield and beset by problems of minor variations in the many optical and chemical processes involved. Six Sigma was focused on reducing variation by intensive measurement and analysis of process capability.

The ultimate goal was to achieve a process twice as good as the specification. Then when shift happens, and it inevitably does, the customer will still never see a defect. A defect being defined at outside of measurement specification. Reducing variation was the continuous imperative, more and more process improvement until the “world class” target of twice as good as spec was achieved.

Projects were originated at the manufacturing cell level targeting the specifications and deliverables of the next “customer” of the process. Likely an internal customer on the route to the final end user. Projects were selected and prioritised on the returns from cost reduction. Cost of Poor Quality or COPQ was the clarion call with any savings in COPQ immediately visible in the bottom line – profit. Those COPQ savings may come from scrap, rework, labour or materials, un-necessary inspection as well as inventory and cash flow.

Listening to "The Voice of the Customer"

That early enthusiasm for financial returns from a Six Sigma project tended to overshadow other equally important goals. Seeing your product or service from the customer viewpoint became a key directive for project selection. Put simply if you can make your product or service better or deliver it faster or provide it cheaper than the competition you will gain market share.

The old joke that you can only have any two of better, faster, cheaper must not be followed. You must not devalue or degrade any one of those in favour of another. All Six Sigma projects start with an evaluation of the Voice of the Customer to gain understanding of the deliverable specifications. Then they proceed with evaluation of the current state of process capability in meeting those specifications.

D.M.A.I.C. — The Stages of a Six Sigma Project

A Six Sigma project follows a strategy using the DMAIC mnemonic as guide:

• Define the problem and set a goal for the next level to achieve. It should be measurable so that the target and it’s achievement is clear. Review this as a project charter with the process owner and only proceed with clear business approval.
• Measure — Evaluate the current state of the process, how bad is it really, how far from the target goal are we now.
• Analyse — Understand the root cause of the problem responsible for the poor quality or process variation.
• Improve — Use the skills and experience of the whole team to develop a solution. Prove your ability to control the problem and improve the process.
• Control — Roll out or implement the new process or improved methods and impose control measure to make sure that it stays fixed. Finally celebrate the success and recognize and reward the achievements of the team. After that start over with the next project! That strategy lends itself to projects in both manufacturing and in business process.

What About Other Strategies?

The five structured phases with clear purpose and gate or stage reviews helps to guide both the team and the process owner or sponsor of the project. Six Sigma isn’t the only available strategy for continuous improvement. There must be at least a dozen alternatives. Lean (also called Toyota Production System), Agile, Kaizen, PDCA, 8D, A3, TQM, TOC, BPM, PLM, RCM, TPM, QRM… I confess I had to look some of these up.

So which is the best one for your business? Some of these have very limited or specialist application but they all tend to be developments of what went before. You could probably trace most of them back to Demming, Juran, Ishikawa, the quality gurus of the 1950’s. Everyone steals the best features of an earlier strategy and develops it to meet the current need. There is a continuous development cycle in methodologies!

What About Lean Six Sigma?

In the last few years we have seen the emergence of Lean Six Sigma, which is a union of both the Six Sigma strategy from Motorola and Lean or the Toyota Production System. It recognizes that there isn’t one size that fits all but gives you permission to use the best tool for the job. For me you can have the best of both and that would span projects in high volume repetitive manufacturing, transactional or specialist business processes and cutting edge technical equipment. At least until something better comes along.