Lean Manufacturing and Lean Six Sigma:
an Executive Summary

Lean manufacturing enthusiasts note that Six Sigma pays little attention to speed and flow, while Six Sigma supporters point out that lean fails to address customer needs and variation. At Catalyst Connection, we’ve found that the two techniques work best as allies rather than rivals. First, let’s examine them separately.

The textbook definition of lean is “a systematic approach to identifying and eliminating waste through continuous improvement by flowing the product at the customer’s demand.”

In a decades-long drive, Toyota pioneered lean philosophy and emerged as the world’s largest auto maker. The Toyota Production System (TPS) shifted the focus from individual machines to the flow of product all through the process. The steps were small, but their collective impact has been global, and today consultants apply TPS lessons to just about any kind of product.

With TPS, each work station down the line tells the previous station what it needs. Right-sized equipment fits the actual volume required. Self-monitoring machines ensure quality. Equipment lines up in process sequence. And quick-setup techniques enable one machine to make many different parts in small batches. Result: lower costs, greater variety, higher quality, and faster throughput.

A key TPS concept is “waste” — not just physical scrap, but what the Japanese call muda: any condition or activity that’s unproductive or doesn’t add value. Toyota targeted seven kinds of waste:

• Overproduction (making anything before it’s needed)
• Transportation (product movement not essential to the process)
• Waiting (operator or machine idleness between steps)
• Inventory (components, raw materials, work in progress, and finished products not being processed)
• Motion (nonessential movement of people or machines)
• Over processing (using or doing more than required)
• Defects (finding and fixing defects)

“The Machine that Changed the World” (1990) and “Lean Thinking” (1996) described lean for Western readers, distilling it to five steps:

1. Specify value from the end customer’s standpoint
2. Identify all the steps in the process, and eliminate any that don’t create value
3. Integrate the remaining steps so the product flows smoothly toward the customer
4. Let the customer’s order pull each batch through the system.
5. Pursue perfection endlessly, reducing steps, time, and information.

As lean spreads around the globe, it’s outgrown not only the auto industry but the whole manufacturing sector, taking root in soils as diverse as logistics and distribution, services, retail, healthcare, construction, maintenance, and even government.

At the same time that lean was gaining acceptance as a continuous-improvement tool, Six Sigma was emerging as the leading approach for quickly eliminating defects.

It was inevitable that the process improvement community would look for ways to integrate the greatest strengths of the two methodologies. After all, lean alone cannot bring a process under statistical control, while Six Sigma by itself cannot dramatically improve process speed or reduce invested capital. What was needed was a balanced, complexity-reducing process for improving the quality of service as defined by the customer within a set time limit.

The result was Lean Six Sigma, which fuses two powerful tools in a single, coordinated drive for rapid, high-impact business improvement. What sets it apart is the recognition that an organization cannot settle for just the speed of lean, or just the quality of Six Sigma. Probably its most significant feature is its concentration on bringing about focused improvements in less than one month. Lean Six Sigma maximizes shareholder value by achieving the fastest gains in customer satisfaction, cost, quality, process speed, and invested capital.