Lean Manufacturing vs. Six Sigma: Which is Right for Your Plant?

When it comes to improving manufacturing processes, there are two well-known management techniques: Lean Manufacturing and Six Sigma. But, what’s the difference between Lean Manufacturing and Six Sigma, and which methodology is right for your plant? This blog will compare the core principles of each practice so plant management can decide between the two or adapt an approach that incorporates the best components from each to help maximize efficiency and minimize waste.

Lean vs. Six Sigma: The Basic Principles

To help determine which technique will provide the most powerful benefits for your plant, let’s first identify the basic goals of each.

In Lean Manufacturing, the main objective is optimizing production and improving efficiency by reducing waste, which is defined as any activity that does not add value to the finished product.

In practice, there are seven types of waste in lean manufacturing, often referred to as the “Seven Deadly Wastes,” including:

1. Overproduction: When more products are produced than are in demand, it results in wasted raw materials, labor, inventory and capital spending.
2. Inventory: When extra products or inventory are stockpiled, capital is tied up and storage space is wasted.
3. Defects: Production of faulty products wastes raw materials, finished components and products, labor and money spent on disposal.
4. Motion: When there are unnecessary steps in the production process, it wastes employees’ time, as well as money spent on labor that does not add value to the final product.
5. Over-processing: Over-designing or refining the finished product often adds more features or value than the consumer desires, wastes time in the design and production process and adds little value to the product or customer.
6. Waiting: Bottlenecks during production and lags between process steps waste production time and labor hours.
7. Transportation: Transporting materials and products long distances between facilities or warehouses wastes fuel, time and money and adds little value.

In addition to the seven types of waste in Lean Manufacturing, there are five key principles, including:

The benefits of Lean Manufacturing include increased efficiency and productivity, reduced costs, improved customer satisfaction, minimal lead times and sustainability.

Alternatively, the core objective of Six Sigma is to devise a data-driven strategy that focuses on process efficiency and waste elimination in order to build sustainable business growth and increase customer satisfaction.

Six Sigma relies on one of two approaches, known as either DMAIC or DMADV. These are acronyms for Define, Measure, Analyze, Improve and Control (DMAIC) and Define, Measure, Analyze, Design and Verify (DMADV).

Both Six Sigma approaches begin by defining a problem or process improvement goal, measuring the current process to collect data and then analyzing gathered data to determine the root cause of the issue or defect. DMAIC then focuses on improving the process and adding control methods to sustain process efficiencies. DMADV follows the same first three steps and then, instead of improving existing processes, it focuses on designing a better one and verifying that the new approach satisfies expectations.

The benefits of Six Sigma include reduced costs and enhanced revenues, improved productivity and efficiency, minimized waste, better product quality and greater levels of customer satisfaction. 

What’s the Difference Between Lean Manufacturing and Six Sigma?

While it may seem as if both management strategies improve efficiency and reduce costs associated with waste, there are some differences in how they achieve process optimizations.

Key differences between Lean Manufacturing and Six Sigma include:

• The Approach: Lean Manufacturing relies on methodologies like creating a smooth production flow and using pull systems to reduce waste and optimize operations. Six Sigma is a data-driven approach that studies and solves business problems.
• Focus Areas: Lean Manufacturing focuses on eliminating waste and improving process flow, while Six Sigma focuses on reducing defects and eliminating process variations.
• Tools: Lean manufacturing uses Kaizen and tools like process mapping, where Six Sigma uses data, charts and analysis to improve the process and reduce waste.
• Results: Users of Lean Manufacturing can expect to reduce bottlenecks, lead times, scrap and waste, which will result in increased productivity, efficiency and financial benefits. Users of Six Sigma can expect to see fewer defective products and higher quality products, which will result in increased productivity, lower costs and increased product quality and customer satisfaction.
• Speed of Implementation: Lean Manufacturing is typically easier and faster to implement and yields results sooner, while the data collection and analysis of Six Sigma require a longer time to implement and achieve results.
• Areas of Implementation: Lean Manufacturing is generally applied to the plant floor and operational processes, while Six Sigma can be used on the shop floor, as well as in the sales, marketing and customer service components of a business.

Despite the differences between Lean Manufacturing and Six Sigma, the two strategies can be combined to provide more powerful improvements. Often called Lean Six Sigma, this approach adapts and combines the best practices of each methodology to optimize operations, reduce waste and defects and provide more value to customers.

By understanding the difference between Lean Manufacturing and Six Sigma, plant management can determine which strategy will improve efficiency and productivity, while eliminating waste and reducing costs based on the needs and objectives of the business. For more information on how to apply Lean Manufacturing, Six Sigma or a combination of the two, please contact the manufacturing experts at JHFOSTER.