A Guide to Implementing Lean Six Sigma
by Carl Wright


If you're in the business world, you have either heard of lean manufacturing or six sigma. Almost every company in either the service or manufacturing sector has adopted one of these two disciplines as an improvement methodology.

Some businesses have adopted both methods using the term lean six sigma. It is the name most often given to the combination of lean manufacturing and six sigma principles.

The reason most companies have adopted one or the other is simply because their employees have been trained on one or the other disciplines. The lucky ones have employees trained in both lean manufacturing and six sigma, and understand it only makes sense to combine both for maximum improvement.

Lean manufacturing follows a model of Plan-Do-Check-Act (PDCA), and six sigma follows a model of Define-Measure-Analyze-Improve-Control (DMAIC).

It takes a lot of training to be an expert in both fields, and therefore very few companies have enough expertise to implement lean six sigma. However, it is worth the effort, as it doubles the amount of business improvement tools and enables problems to be solved using the "correct" tool rather than trying to fit a certain methodology to the problem.

The roadmap to lean six sigma includes following the DMAIC phase.

First define the problem. This is often the most time consuming, as there are many competing projects. The project selection process should be based on the company objectives and value of the project. Many tools are used in the define phase, some of which are listed below.

  • Project Charter
  • Flow Charts
  • Process Mapping
  • Work Breakdown Structure (WBS)
  • PERT Charts
  • Affinity Diagram
  • Nominal Group Technique (NGT)
  • Prioritization Matrix
  • Gannt Charts
  • Voice of the Customer (VOC)
  • CT Trees (Critical to Quality, Critical to Schedule, etc)
  • Pareto Charts
  • Rolled Throughput Yield (RTY)
  • Kano Model

Measure the current state. The tools used depend on whether it's a pure lean manufacturing, six sigma, or combined lean six sigma project. However, the the tools most commonly used for this phase are:

  • Probability and Statistics
  • Data Collection
  • Measurement Systems
  • Process Level Flowcharts
  • Process Level Mapping
  • Histogram
  • Stem and Leaf Plots
  • Pareto Charts
  • Cause and Effects Diagram and Matrix
  • FMEA (Failure Mode and Effects Analysis)
  • Control Charts
  • Process Capability
  • Gage R & R Studies
  • Frequency Plots
  • Confidence Intervals
  • Process Sigma

Once the current state is measured, it needs to be analyzed. Most six sigma projects take quite a while in this phase. For example, detailed analysis of markets, machines, people, shifts, and outputs take considerable time. A pure lean project may only take a few hours or days to analyze. For example, if the project is to reduce setup times, the measure phase may take a few hours to measure the current setup times under various conditions.

  • Brainstorming
  • 5 Why's
  • Value Stream Mapping
  • Control Charts (XBar & R, np, C, U, p)
  • Scatter Plots
  • Regression Analysis
  • Design of Experiments (DOE)
  • Hypothesis Testing

The next step is improvement. This could range from a quick kaizen type project of moving machinery, making operational changes for OEE (overall equipment effectiveness) improvement, or it could be a several week DOE (design of experiment) and regression analysis process.

  • Design of Experiments (DOE)
  • Hypothesis Testing
  • Brainstorming
  • Cause and Effect Diagram
  • Box Whisker Charts
  • Process Mapping
  • Lean Manufacturing Tools:
    • SMED (Single Minute Exchange of Die)
    • Standard Operations
    • Kaizen
    • Value Stream Analysis
    • Work Simplification
    • Methods Improvement
    • Error Proofing
    • 5S

The next step is controlling the improvement. The last thing any team wants it to obtain improvement and not sustain it. This could include training, demonstration by employees, standard operations, SOP's. or multiple process control charts.

  • Control Charts
  • X Bar & R
  • I-MR
  • p
  • np
  • c
  • U
  • EWMA
  • Standard Work
  • Visual Management
  • Performance Management
  • Process Mapping

Many implementers get hung up on the project time. Some training programs suggest a black belt project takes a few months on average. Most lean training talks about speed with processes such as kaizen blitz. The projects should take as long as necessary and solved using the tools necessary to obtain maximum improvement. If that means one day, then it is a one day project. If it means 3 months, then so be it.

The DMAIC process does not have to take weeks. There are problems that can be defined, measured, analyzed, improved, and controlled in a matter of days. Just because a problem can be solved quickly does not mean it is only a lean or other type of project.

However, not every project needs a process. For example, if a problem arises and the answer is known, it should be solved once and for all forever. If something needs done to sustain it, then those tools should be used. That does not mean it needs a full blown project.

The bottom line is use an improvement methodology when you need it, and use the tools necessary to solve the problem. When tools are forced on an organization rather than pulled into problems, the system is sure to fail.

Implemented properly, focusing on the primary strategic objectives of the company, lean six sigma will provide enormous benefits in terms of profitability, revenue, quality, cost, productivity, and morale.


The Author

  Carl Wright is an industrial engineer, ASQ Six Sigma Black Belt, and Master Black Belt. Carl has over 20 years of continuous improvement and change management experience. Visit lean six sigma for more information.
Many more articles in Performance Improvement in The CEO Refresher Archives

Copyright 2008 by
Carl Wright. All rights reserved.

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