We are no strangers to Lean or Six Sigma. Through the improvement of lean production mode, many manufacturing enterprises have obtained rich profit returns. On the other hand, the Six Sigma management methods that Motorola, General Electric and other world-class companies are keen on also attract us. At present, many domestic companies are also eager to introduce six horses, including well-known large companies at home and abroad, hoping to guide enterprises to Excellence through the innovation of six horses, and small and medium-sized companies with low visibility, hoping to break through the cocoon and by going up one flight of stairs. After lean, Six Sigma is more like a storm of management thoughts, sweeping all walks of life, and no one can refuse the temptation to realize the enterprise dream. Which is better, lean or six-fitness, is not only a puzzle in the industry, but also a research topic in theoretical academic circles. In some management frontier camps, lean and six sigma are organically combined, which is called LeanSigma by management scholars, and it is a nuclear weapon for enterprises to effectively manage (that is, a management weapon to cultivate their core competitiveness).
Question 1: What's the difference between lean production and six sigma?
This question can usually be understood as: "Should I adopt lean production or six sigma to improve my business activities?"
Before answering this question, let's briefly review the background of these two engineering improvement methods. Lean production is put forward on the basis of Toyota production mode in Japan. It was first put forward in 1990' s by experts from the Digital International Automobile Planning Organization (IMVP) of the Massachusetts Institute of Technology, USA. Lean is a praise for the Japanese "Toyota production mode", that is, lean, that is, less and refined, without putting in redundant production factors. Benefit, that is, all business activities should be beneficial, effective and economical.
At the beginning of the 20th century, Ford Motor Company established the first automobile production line. Since then, Ford production mode, that is, large-scale assembly line production, has become the main feature of modern industrial production. Mass production mode is to reduce production cost and improve production efficiency on the basis of standardization and mass production. This method adapted to the national conditions of the United States at that time. However, after World War II, the society has entered a new stage of market demand diversification, accordingly, industrial production is required to develop in the direction of multi-variety and small batch, and the weakness of single-variety and large-batch flow production mode is becoming increasingly obvious.
In 1950s, after the war, Japan's economy was depressed, lacking capital and foreign exchange, and its economic and technological foundation was far from that of the United States. The law of "scale economy" has met with severe challenges here. How to establish Japanese automobile industry? Toyota Hideki and his partner Taiichi Ono conducted a series of explorations and experiments after inspecting the automobile factory of Ford, an old American company, and put forward solutions to the problems according to Japan's national conditions. After more than 30 years' efforts, a complete Toyota production model has finally been formed, making Japan's automobile industry surpass that of the United States.
Lean production combines the advantages of mass production and single-piece production, and strives to achieve low-cost production of multi-variety and high-quality products in mass production. Lean production has become the best production organization system and mode in the current industry. Its guiding ideology is to optimize the whole production process, improve technology, straighten out logistics, put an end to overproduction, eliminate ineffective labor and waste, effectively use resources, reduce costs, improve quality, and achieve the maximum output goal with the least input.
The main features of LP are (1) pull type, (2) just-in-time production, (3) balanced production and (4) single flow.
The concept of Six Sigma was first put forward in 1987 by George Fisher of the Communication Business Department of Motorola, USA. At that time, Motorola had some quality policies, but there was no unified quality strategy. Like many other companies in America and Europe, its business is being eaten away by Japanese competitors. In order to improve the competitiveness of product quality, the innovative and improved six sigma concept has been vigorously promoted throughout Motorola. After adopting six sigma management mode, the company's productivity increased by 12.3% on average every year. In the middle and late 1990s, Jack Welch, president of General Electric Company, carried out the Six Sigma management method in the whole company, and achieved brilliant results, which made this management model truly famous.
Six Sigma is a nearly perfect quality management method based on data. Sigma is a Chinese transliteration of the Greek letter σ, which is used to represent the standard deviation in statistics, that is, the degree of data dispersion. For continuous measurable quality characteristics: use "σ" to measure the deviation of quality characteristics from the target value as a whole. Several Sigmas are statistical measures of quality. Any working procedure or technological process can be represented by several Sigmas. Six fit horses can be explained as 3.4 mistakes per million chances, that is, the pass rate is 99.99966%. The passing rate of three eligible horses is only 93.32%.
In essence, Six Sigma management method is an efficient enterprise process design, improvement and optimization technology, which evolved from Total Quality Management (TQM) and provided a series of new product development tools that are also suitable for design, production and service. The key point of six-horse management method is to regard all work as a process, analyze the factors affecting quality in the process with quantitative methods, find out the most critical factors and improve them in order to achieve higher customer satisfaction. From the current practice, there are two main types of six-fitness horse management: six-fitness horse improvement and six-fitness horse design. Nowadays, Six Sigma has gradually developed into a criterion for determining enterprise strategic objectives and product development and design with customers as the main body, and it is a quality management concept for enterprises to pursue continuous progress.
The main characteristics of the six-horse management law can be summarized as follows:
(1) Customer-centric;
(2) process-centered;
(3) scientific problem-solving methods;
(4) training expert manpower;
(5) Carry out activities in the form of topics;
(6) Pursuing huge financial effects.
However, for different industries, for many enterprises at different management levels who are eager to seek management improvement or breakthrough, should they adopt lean production mode or implement six sigma? Some entrepreneurs are asking, after all, lean production has achieved great success in Toyota, Japan, as well as in automobile-related industries. The characteristic of our enterprise is mass production of small varieties. Is it also applicable to lean production? Compared with discrete manufacturing, how does process manufacturing promote lean production? Some entrepreneurs who are concerned about Six Sigma are asking, our enterprise management foundation is weak, and the quality level is less than 3Sigma. Is it not suitable for the implementation of six sigma? Or which is more effective?
The presentation and development of each management concept has never been isolated and static. Lean production is still developing, and the theory of six sigma is still being enriched and improved. There are differences between them, but there are also many similarities and mutual support. Some enterprises, such as Sino-American SmithKline Pharmaceutical Co., Ltd. in Tianjin, have been promoting the combination of the two, that is, lean Sigma innovation.
The differences between lean production and six sigma are discussed as follows:
1. There are different requirements for the basic management level of enterprises.
Lean emphasizes step by step. In order to truly realize demand-driven just-in-time production, there are high requirements for enterprises' 5S visualization, equipment independent guarantee system and employees' multi-skills. Otherwise, pulling cannot be realized, or short-term partial pulling cannot be effectively maintained because of changes in equipment, personnel and quality, which is also a "rebound" that many entrepreneurs are worried about; The Six Sigma method clearly shows that the purpose of an enterprise is to make a profit. For enterprises at different levels, it does not mean that enterprises with less than 3 horses are not suitable for implementing 6 horses by defining their own problems to carry out continuous DMAIC cycle activities. In fact, it is suitable for enterprises of different levels in all walks of life.
2. Different ideological categories.
Lean is based on pull-type just-in-time production to eliminate the waste of warehouse work in enterprise production activities. Lean thinking pursues the best resource allocation and meets customer requirements as soon as possible. Six-fitness method is a scientific and optimized thinking process to solve problems. Avoid blind action until the core of the problem is determined. Just like Deming cycle in modern management, the Six Sigma advocated by DMAIC has become an ideological weapon for enterprises to solve core problems. Enterprises can apply six sigma method to solve the problems in direct production departments and indirect production departments such as R&D, sales and procurement. Lean production is a sharp weapon for enterprises to eliminate production waste.
3. The starting point of solving the problem is different.
Lean production takes the reduction of seven kinds of MUDA as the core goal and directly suits the remedy to the case. Starting from the customer's demand (VOC/VOB/COPQ) (the six characteristics of the six horses), the six horses list all the topics that need to be solved through top-down policies, and select the topics that have the greatest impact on customers as the six horses to implement.
4. Different understanding of financial impact.
The realization of lean production mode has contributed to the financial operation of enterprises subjectively because it has eliminated or reduced seven kinds of waste. Objectively, the impact of this contribution on the financial environment of enterprises has not been scientifically analyzed and planned (the financial contribution may be minimal). One of the direct characteristics of Six Sigma is to focus on financial performance and use Pareto Law to select the projects that can bring the most profits to the enterprise, that is to say, projects that do not make money or make less money are not given priority.
5. Use of tools of the system.
Lean production relies more on experts' experience when solving problems, and applies many technologies, such as customer value stream analysis, action analysis and time measurement, factory facilities layout technology, Jidoka (automation) and anti-fraud, all-round worker training, 5S/TPM and so on. Six Sigma method can apply all applicable tools, including the above tools, but it is not a simple superposition of various tools, but a logical combination of various tools, and mastering this method can not only become an expert in a certain field, but also quickly approximate the solution.
6. Application of statistical knowledge.
Compared with lean production, Six Sigma has applied a lot of statistical techniques. Through quantitative analysis of indicators, you can verify your own judgment and avoid relying on experience, intuition or taking it for granted when solving problems. Experience is of course important. Six Sigma method concentrates all the wisdom in the team organization, transforms the actual problem into a statistical problem (establishes a mathematical model Y=F(X)), and then obtains the actual solution from the statistical solution.
Perhaps because of the application of statistical technology, Six Sigma is not as "approachable" as lean production. Indeed, six horses focus on data facts, but statistical technology does not mean six horses, and there are no projects that fail because of insufficient statistical application, but many innovative projects fail because they chose the wrong direction from the beginning.
7. The understanding and handling principles of fluctuations are different.
Fluctuation exists objectively, and most of the reasons for the failure of enterprises to implement lean production are fluctuations. These fluctuations can be summarized as the fluctuations of people, machines, materials, methods, measurement and environment (i.e. 5M 1E). The reason why 5S/TPM and other methods should be introduced before implementing lean production is to improve the basic management level of enterprises and minimize fluctuations. Ordinary enterprises are often eager for success, and the short-term effect is difficult to maintain. Six Sigma regards fluctuation as the enemy and tries to eliminate or reduce it. When the fluctuation is reduced, the quality will be improved. The so-called improvement of enterprise management level is actually to reduce the fluctuation of 5M 1E factor.
8. Different personnel training mechanisms.
People are the main participants in enterprise management activities. Through the practice of lean production, we can improve the innovative consciousness of enterprise cadres and cultivate a group of innovative backbones. However, the cultivation of such talents is not systematic, but spontaneous, learning by doing, and uneven due to personal understanding. Six Sigma pays attention to systematic manpower training and establishes internal incentive mechanism. Through professional training, we have trained our own problem-solving experts and set up a number of inter-departmental problem-solving teams centered on the black belt.
Question 2: When will lean production be applied? When do you apply for six sigma management consulting?
To put it simply, if you are faced with the situation that customer demand changes greatly, and there are many varieties and few batches produced, and you can directly solve the problem with lean, then you should choose lean without hesitation, that is to say, lean provides solutions to known problems. For discrete manufacturing industry, due to the circulation of a large number of WIP between processes, the waste of WIP is caused and the manufacturing cycle is prolonged. After implementing lean production in one piece flow, immediate results can be achieved. However, six sigma can not only be used to solve lean problems, but also seek to solve non-production problems. For the process-oriented manufacturing industry with few varieties and mass customization, the application of Six Sigma can clarify the existing problems of enterprises and improve their operating conditions from many aspects such as quality, cost and customer satisfaction.
Question 3: How to combine lean production with Six Sigma management consulting?
Lean method seeks to minimize all waste in production activities (called the big wood in the value stream). Big wood includes all kinds of defective works, not just defective products. The waste of time, action and material is also a big wood.
Applying the thinking process of Six Sigma in lean production can obtain a scientific way to reduce waste, which is conducive to identifying and reducing fluctuations and finding the root causes of fluctuations and waste through quantitative methods. In the following aspects, the combination of the two methods can complement each other:
1. When grasping the current situation and collecting data, we can apply Six Sigma's problem definition, data collection plan and analysis tools.
2. When analyzing the current layout and process, you can apply the flow chart of Six Sigma.
3. When measuring and analyzing the process time, the data collection tools and skills of Six Sigma SPC can be applied.
4. In order to calculate the process capability and production beat (T/T), we can apply Six Sigma's process capability analysis Cp/Cpk.
5. When confirming the effectiveness of the improvement, six sigma hypothesis test and SPC can be applied.
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To sum up, it is not necessary for the business community to discuss the advantages and disadvantages of lean production and six sigma method. Problems and solutions have been identified and can be implemented directly. Simple methods can do it, not complicated. When it is necessary to clarify the key problems that plague the development of enterprises, or to intervene in management or non-production fields, six sigma management will help you to continuously improve together with lean production.