Six Sigma and Lean are different but closely related improvement methodologies. Using elements from both can help gain synergy for your project. Six Sigma is a rigorous project-driven approach to reducing variance and eliminating defects in processes. Lean, meanwhile, is fundamentally about helping people do more with less — delivering more customer value with less waste.
You’ll find that the methods and toolsets of Lean and Six Sigma are often combined. As a Six Sigma practitioner, you can bolster your approach by taking advantage of Lean methods and tools.
Add customer value
Creating value for the customer is a foundational principle of Lean. Part of Six Sigma addresses how you ascertain whether a process or activity is adding value. This same definition is a core tenet of Lean practice. An activity or process is considered to be value add only if it meets all three of the following conditions; otherwise, it’s non-value add, or waste:
It must transform the product or service.
The customer must be willing to pay for it.
It must be done correctly the first time.
Map the value stream
VSM helps you get the big-picture view of your processes. Use this approach to effectively see a process end-to-end — from suppliers through to customers and end-consumers. This strategy helps you prevent optimizing one subprocess at the expense of another one in the value stream. Learn how to create and leverage value stream maps and be ready to infuse this method appropriately into your DMAIC projects.
Strive for flow
One of the basic Lean principles for effective production is flow. A stream of single items progressing through a process turns out to be more optimal and ideal than any alternatives — especially batch. Within your Six Sigma projects, identify and enact process changes that promote this ideal: the concept of single piece flow.
3-Gen: Go to gemba
Six Sigma is often highly analytical, which sometimes leads to a tendency to perform Six Sigma analysis and project work in a location removed from where the process or defects are actually occurring. Lean has an approach called 3-Gen.
Derived from Japanese words — genchi, genbutsu, and genjitsu — 3-Gen is the practice of going to gemba, or physically going to where the action is, where value is being created, or where waste is occurring so you can observe firsthand what is happening and get real data and facts to solve problems and improve processes. Working from second-hand knowledge never results in the kind of understanding required to make breakthrough improvements.
Muda-Mura-Muri: Expand your definition of waste
In Six Sigma, your focus is primarily on variance and defects. Lean has a broader definition of muda (Japanese for waste) that officially includes seven forms of waste: transportation, waiting, overproduction, inventory, movement, extra processing, and of course defects. In addition, mura is waste due to unevenness or variation, and muri is waste caused by overstressing people, equipment, or systems.
5S the workplace
The Lean practice of 5S is important as a fundamental behavior to reduce waste through workplace organization. Sort, straighten, scrub, standardize, and sustain — these simple and practical steps lead to an improved work environment.
Keep simple things simple
Not all improvement efforts need the analytical rigor and depth of what a Black Belt does within a DMAIC project road map. Some efforts are better suited to the Lean kaizen approach of everyday improvement. Instead of tackling a three-month Six Sigma project, Lean teams make incremental improvements in a matter of routine. The Deming cycle of Plan-Do-Check-Act fills in this way, alongside the Six Sigma improvement process of DMAIC.
Teach kaizen — the acts of everyday improvement — and help people think this way. Kaizen is a strongly principled underpinning that naturally addresses a broad swath of your needs and enables your Six Sigma projects to run better.
Everyone plays a part
In Six Sigma, the specialists — the Black Belts, Master Black Belts, Champions, and even Green Belts — perform the bulk of the DMAIC improvement process. They lead, manage, and perform most of the Six Sigma project work. Lean is different. In Lean, improvement projects involve everyone — not just the specialists. Everyone who is involved in the process in any way is included.
Because not everyone is trained in the advanced methods and tools of Six Sigma, Lean team project members don’t address the issues with the same level of statistical depth and rigor. Many process challenges require changes in behaviors, attitudes, and activities. For that, it’s more about involvement and inclusion than about deep statistical analysis. If the process challenge you’re facing is more about people, Lean provides a complimentary approach.
View improvement as a mindset
Most Six Sigma training is geared toward Black Belts and Green Belts. But remember the Yellow Belts — that is, everyone else. In your Six Sigma deployment, you should provide training to everyone in your organization because you want everyone thinking in a data-driven, cause-and-effect process manner.
Lean really emphasizes this improvement mindset. In Lean, everyone feels compelled and is organizationally empowered and encouraged to make improvements every day and all the time. This thinking is the essence of kaizen. By incorporating this fundamental Lean principle in your Six Sigma practice, you expand your initiative’s reach, effectiveness, and sustainability.
Make sure managers improve, too
Process improvement isn’t just for the so-called worker bees; managers and executives must be actively engaged. Sometimes in Six Sigma, the managers believe their jobs are done after they’ve endorsed and encouraged process improvement practices. But as important as this support may be, that’s not the whole story.
In Lean companies, all the top managers are involved to the extent that they conduct their own daily improvement work. No one in these types of successful organizations is exempt from joining the effort.
This leadership philosophy from Lean is invaluable to companies doing Six Sigma: Managers develop the mindset, learn the tools, involve themselves directly in their application, and directly lead their staffs by example. In many Six Sigma initiatives, companies require all managers to complete Green Belt training.