Lean manufacturing and six sigma

What are Lean and Six Sigma?

Many people are familiar with the terms ‘Lean Manufacturing’ and ‘Six Sigma’, but are unsure as to which approach is right for their business. Six Sigma works on the principle that reducing variation gets to the root of any problem. And many people also see it as a technically superior way of working. On the other hand, Lean Manufacturing uses basic improvements to make business processes more effective.

What is Lean Manufacturing?

The essence of lean thinking is grounded in the Toyota Production System (TPS), which considers people and processes to be the two main pillars of any business.

Engineer Taiichi Ohno is credited with developing the principles of ‘Lean’ production after World War II. His philosophy, which focused on eliminating waste and empowering workers, reduced inventory and improved productivity.

The term ‘lean’ is used because Lean Manufacturing uses less:

•  Human effort in the factory
•  Manufacturing space
•  Capital investment
•  Materials
•  Time between the customer order and the product shipment.

The basic goal is to get more done with less, by:

•  Fewer resources for the same output
•  Minimising inventory at all stages of production
•  Shortening product cycle times from raw materials to finished goods to eliminate waste

Lean is a strategy for remaining competitive by identifying and eliminating wasteful steps in products and processes, using the following practices:

•  Eliminating waste and loss
•  Minimising inventories
•  Maximising flow
•  Pulling production from customer demand
•  Meeting customer needs
•  Doing it right the first time
•  Empowering workers
•  Designing for rapid changeover
•  Creating a culture of continuous improvement
•  Partnering with suppliers

What is Six Sigma?

Six Sigma was originally developed as a set of practices designed to improve manufacturing processes and eliminate defects. But its application was subsequently extended to other types of business processes as well.

The particulars of the methodology were first formulated by Bill Smith at Motorola in 1986. Six Sigma was heavily inspired by six decades of quality improvement methodologies, such as quality control, TQM, and Zero Defects, based on the work of pioneers such as Shewhart, Deming, Juran, Ishikawa, Taguchi and others.

In the Six Sigma approach, the view on waste is that "variation is waste". In practising Six Sigma, the DMAIC method is used to:

1.  Define - goals and the scope of the improvement project
2.  Measure - the performance of the current procedures or processes
3.  Analyse - current performance in terms of the future requirements
4.  Improve - current methods to the required level
5.  Control - institutionalise the improvements

Six Sigma is a ‘problem-focused’ methodology, and the primary toolset of Six Sigma is maths and statistics.

Is Lean or Six Sigma right for your business?

Lean thinkers believe that using resources for any goal other than value for the customer, is wasteful, and should be eliminated. ‘Value’ is defined as any action or process that a customer would be willing to pay for.

Six Sigma seeks to improve the quality of process outputs by identifying and removing the causes of defects and variation in manufacturing and business processes. It uses a set of quality management methods, including statistical methods, and creates a special infrastructure for people within the organisation ("Black Belts" etc.), who are experts in these methods. Six Sigma can be used to solve specific problems, where the root causes are complex and correlated.

In summary, there are several similarities between these two improvement practices:

Both approaches require the use of teams, be they Kaizen teams or Six Sigma project teams. Both approaches function best if they are managed by experienced (certified) people, such as black belts, green belts, or lean consultants. Both approaches require behaviour change and systems change, if you want to see true improvement. And both approaches can save you significant time and money if they are effectively implemented.

Six Sigma and Lean go together hand in hand, even though they are different. Despite any distinctions, the two go very well together. For example, it could be logical to focus on Lean to achieve process improvement, and at the same time develop a deeper understanding of the process. If more work is needed, Six Sigma could be used to reduce process variation.

A Chinese proverb says “I forget what I hear, I remember what I see, I know what I do!”. Since the best way to learn about Lean or Six Sigma is by doing it, we apply these models routinely to different situations, but please remember: like any skill, these take both practice and discipline!