Lean and Six Sigma

Lean is a continuous improvement initiative. Its key focus area is the streamlining and improving of processes. Essentially it’s about constantly reducing the amount of time taken to receive payment for a product or service, from the time that an initial order is placed. This reduction is done by removing time and waste from the entire value stream. All this will lead you to better efficiency, quality, and customer satisfaction.

Lean and Six Sigma Differences

Six Sigma and Lean are extremely complementary methodologies and in fact overlap a great deal. However, it’s important to recognize that there are important differences between the methodologies.

Focus – The focus of Six Sigma is on eliminating sources of variation or the number of mistakes you’re making. The focus of Lean is in reducing time and waste in processes. It’s important to understand that with Six Sigma the focus is very narrow, for example the performance of a single step in a process and how the quality can be improved at that single point in the value stream. Lean looks at the entire process and what can be done to improve the entire ability of the process to deliver things faster, with better quality, and more efficiency at the same time.

Methodology – The methodology associated with Six Sigma is a very rigorous five-step process – Define, Measure, Analyze, Improve, and Control (DMAIC) – where you’re gathering data and going through a number of different steps. With Lean there is less focus on the data or at least the precision of it. Lean employs a four-step process:

• identifying opportunities
• designing a solution
• implementing a solution
• ensuring continuous improvement

In Six Sigma, you tend to be very focused on a point in the value stream. The performance, for example, of a single step and your ability to produce quality at that step. Whereas Lean looks at the entire process and what you can do to improve the entire ability of the process to deliver things faster, with better quality, and more efficiency at the same time.

Key Tools – The key tools associated with Six Sigma are very statistical in nature. There are tools for data analysis and management planning. You can also use Six Sigma metrics and the statistical process control tools to bring things under control and keep them controlled. With Lean you use tools like theory of constraints or identifying bottlenecks and breaking them. You may also encounter the concept of Muda, or a Japanese word for “waste.” Some of the other key Lean tools include value stream mapping, kanban, 5S, standard work, and poka-yoke. In total between both of Six Sigma and Lean, there are more than 100 different defined tools that can potentially be used.

Primary Effects – The primary effects of Six Sigma are to reduce variation and defects and getting uniform process output as opposed to Lean, which is about eliminating waste and taking time out of the process wherever you can.

Lean and Six Sigma Integration

By properly integrating Lean and Six Sigma, tremendous value can be created for any kind of organization. For example, a technique that you can employ when performing value stream mapping is to take the output of the value stream mapping with the data. Then you can look at which steps in the value stream account for a lot of variation, most of the effort being expended, or a large amount of money being spent. At the same time, you should examine the steps to identify – which steps make up most of the defects and mistakes that you’re finding across this value stream that affect your customer or drive up your costs. This will help you to identify the key steps which present the most opportunities for improvement. Once this is done, you can decide which tool you should use. You can use Six Sigma to reduce the variation and the number of defects. And you can use the Lean techniques to speed things up and create stability in the process.

Lean and Six Sigma overlap and are very powerful working together in eliminating waste and driving value for any organization. On the Lean side it’s all about speed, flow, eliminating waste of time and effort, knocking down constraints that are blocking the smooth flow of product and value, increasing flexibility, and reducing the complexity. But while you’re working on this you will find many opportunities to strategically and tactically apply Six Sigma concepts. This will help you to focus on what the customers’ needs are and by the same token help in driving down defects and improving performance.

If the primary problems are too much waste, too much inventory, or low velocity processes, then Lean tools should be implemented to fix the issues. However if the issue is too many variations and defects or too little trust in the output, then Six Sigma would be better to use here.

Capacity for change is important. If you want to ease it into the organization, build quick wins, and drive long term behavior, Lean is a good technique to use. With Six Sigma it can take longer because you need data and a longer period of time to show the results.

Also the pervasiveness of the problem is a challenge to think about as well. If it’s isolated, easy to identify, and simple to fix, then Lean tools will work well. If, however, there are lots of mistakes, and defects tend to be the problem, a more intensive and data-based approach is required, and this is offered by Six Sigma.