Lean Bookends for Six Sigma

Lean Bookends for Six Sigma
Douglas Wood

Many managers struggle with the choice of what to do first, second, and how involved to get with the improvement methodologies of Lean and Six Sigma. Lean is intuitive; Six Sigma seems scary with all the math and statistics. They have heard that Six Sigma is expensive, and sometimes it does not work. Lack of resources, training deficits, and other problems appear as major roadblocks.

Many organizations call themselves "Lean," but are practicing an altered form. The lean that Toyota created is all about knowing what you need and doing only what you need. It’s about planning, executing, checking, and then making new plans. It’s very organized, and requires a strong discipline.

Anecdotally, the most common form of Lean is where there are never enough resources to do the job, so you stretch and make do with what you have. Scrambling is a daily task, and what is most important gets done. The rest has to wait. We believe this is not really Lean.

This is not as hard as is seems; Lean and Six sigma fit together, with part of Lean as a starting point, Six Sigma in the middle, and the finish of Lean at the end.

You start with the most intuitive part of Lean. Five -s is a logical staring point:

Mapping workflows and applying value stream maps are another logical early step. Value Stream Maps allow a picture of your production flow, with the key metrics of value included. This gives a common understanding of your operation and provides a basis for Lean implementation.

To make a Value Stream Map, you start with the current state of a process and work from there on improvement. Both the material flow and information flow are included, to show communication needs and linkages between information and product.

Building a common picture of the process such as a value stream map allows teams to identify problem areas, bottlenecks, and waste as well as potential safety problems.

In the map, supplies are received and product is pushed through the operations to reach shipping. Operational metrics included in the map are Cycle Time (C/T), Changeover (C/O), Available Time and Uptime.

The time a product spends from start to finish, including waiting time, is Total Cycle Time. Compare this with the total time that is actually spent adding value to the product.

Other Lean tools are best applied to organizations just starting on this journey or to firms where earlier attempts have been unsuccessful. We offer a full suite of Lean courses to help cover the whole Lean body of knowledge (as defined by the Society of Manufacturing Engineers, The American Society for Manufacturing Excellence, The Shingo Group, and the American Society Quality.)

The use of Six Sigma is best applied to processes that are largely consistent. The early Lean tools allow a more consistent operation, and remove many of the hurdles that Six Sigma tools do not easily handle.

After the operation is relatively consistent, attempts to move to more advanced Lean tools such as demand pull and inventory reduction can prove difficult. This is because the process often shows large variation in output, timing, tools, and techniques. Six Sigma is the best way to achieve low variation and consistent production processes.

Of course, the situation of the actual operational needs to guide where transitions take place. No two firms have the same needs, resources or environment, so those close to the operation must make the choice of tools on the spot. The need for team and individual training is paramount, and while top leaders need to be involved and supportive, the people in the operational levels need to have good knowledge of the tools to apply them correctly and quickly.

Diligent application of Six Sigma will reduce the process variation, and set the stage for the advanced Lean tools: Total Productive Maintenance, drastic changeover or set up time reductions, Kanban inventory controls, single piece flow, demand pull and agile production require a consistent production process.

In summary, early Lean tools allow the establishment of consistent but variable processes, Six Sigma helps reduce variation to low levels, and advanced Lean tools can then be applied to create a world-class operation.