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精益、六西格玛还是精益西格玛?
Lean, Six Sigma or Lean Sigma?

YW.TAN 陈勇华 卓制高级咨询师
译者 吴鸿远 陈瑜 付晓丹
文章类别:制造智慧 |电子期刊号: 2010年第1期 总第13期

The recent financial tsunami has important cost management implications for manufacturing industry, especially in China now in the transition phase of transforming from the biggest to the strongest manufacturing country. Amongst the key tools in any management are Lean, Six Sigma or Lean Sigma and the question we will address here is which one is the best?
金融风暴席卷全球,对整个制造业的冲击不言而喻。而对正处在经济转型关键时期的中国来说,要成为世界最大最强的生产加工基地,更是影响深远。在对精益管理的各个分支做出比较之后,六西格玛或者精益西格玛成为我们关注的重点,究竟哪一个才是真正适用的管理体系?

To answer this question let us look in more detail at Lean, Six Sigma and the combination of both, Lean Sigma.
要回答上述问题,我们必须先回顾一下精益管理、六西格玛管理以及两者的结合——精益西格玛。

Lean or the Toyota Production System was invented as a series of improvement activities in the Toyota Company in the 1950s, at a time when it almost faced bankruptcy. Toyota emerged as the biggest car seller worldwide in 2008, with a profit higher than the total sum profits of the 3 giant US car manufacturers. The book “The Machine that Changed the World” written by James P. Womack, Daniel T. Jones and Daniel Roos in 1990 revealed the Toyota’s secret to a worldwide audience. Subsequently, most of the world’s manufacturing or IE experts have studied in detail the factors responsible for Toyota success. Today most experts classify Lean as “Speed” advantages, which the application of Value Stream Mapping is used to build up the “Lean House” with its 2 major pillars, Just In Time and Jidoka (Autonomation), Fig 1. The Lean house is established upon a series of Kaizen on wastes elimination to achieve uninterrupted flow along the entire stream line. Example, in order to reduce the unnecessary inventory wastes, Toyota invented the JIT system.
精益生产或者丰田生产方式起初是作为一系列改善活动诞生于20世纪50年代的丰田公司,当时丰田几乎面临破产的危险。50多年以后,丰田于2008年一跃成为世界最大的汽车厂商,其利润总额甚至超过了当时美国三大汽车公司的利润总额。19世纪90年代初,James P. Womack, Daniel T. Jones和Daniel Roos出版了风靡世界的管理书籍——《改变世界的机器》,从而揭开了丰田生产体系神秘的面纱。随后,几乎世界范围内的生产管理人员都开始学习丰田生产体系的各个要素。如今很多专家都把“精益”作为企业领先同行的快速优势之一。通过价值流程图分析,在企业内部建立起以准时化生产和自働化(自动防错)为两大支柱的“精益小屋”(如图一)。精益小屋是建立在整个生产线上的持续改善以及不间断流动。举例来说,为了减少所有不必要的浪费,丰田开发了准时化生产管理。


Fig 1. Toyota Production System 丰田生产系统

Six Sigma originated from Motorola in the 80s when the CEO set out to increase the quality by 10x within 5 years time. The quality group to fulfill the company’s goals established an improvement system that brought the company a brilliant decade and won it the “Malcolm Baldrige National Quality Award” in 1988. Honeywell in 1993 and 2 years later General Electric succeeded in absorbing Six Sigma into their quality system. Since then the world has started to realize the benefits of the Six Sigma management system to business success. 3.4 dppm of defects rate is a common goal for all Six Sigma companies that brings tremendous cost saving. Six Sigma is also focused on organization infrastructure, with those key players being given titles like Champion, Black Belt, Green Belt and Master Black Belt. One of the key features of Six Sigma at the very initial stage is cost saving calculation against the P&L account book, which has become the fashion for the world practitioners. Basically Six Sigma has a strong infrastructure organization which relentlessly eliminates the cost of poor quality (or variation) by DMAIC methodologies (DMAIC – Define, Measure, Analyze, Improve and Control Phases) in order to achieve the business goals, Fig 2 of variation reduction and profit maximization. Six Sigma is also classified by experts as a “rigorous” process due to the variation reduction strategy.
六西格玛在19世纪80年代由摩托罗拉时任的CEO创立,当时用了5年的时间产品质量提高了10倍。整个质量团队通过分析公司目标,建立持续改善系统,给公司带来了巨大的效益,并在1988年获得了美国国家质量奖(即波多里奇奖)。霍尼韦尔于1993年引入六西格玛作为公司质量体系不可缺少的一部分。通用也在两年之后使用同样的方法。至此,六西格玛对企业带来的巨大帮助开始在世界范围内得到认知和推崇。每100万个产品中只有3.4个缺陷产品已经成为推行六西格玛最具代表性的成就。六西格玛还可以作为公司组织结构建设的基础,通过六西格玛导师、黑带、绿带、黑带大师等职位的协调,可以在公司内部有效地推行六西格玛。六西格玛最重要的一个基础就是事先对利润(损益)数据的整合分析,这个因素已经为全球工厂所认可。总体而言,六西格玛中DMAIC方法(定义、测量、分析、改善、控制)近乎无情地剔除了整个生产过程中的浪费,从而最大程度地实现企业的预期目标。六西格玛也由此被广大使用者称为最严格的减少变量的管理策略。

Fig 2. Six Sigma improvement philosophies, from variation reduction to profit maximization 六西格玛的改善哲学,从偏差缩减到利润最大化

Key Elements

基础原理

Lean or TPS

精益生产或丰田生产方式

Six Sigma

六西格玛

Goals目标

Maximizing profits利润最大化

Maximizing profits利润最大化

Key Focus关键因素

Waste Elimination杜绝浪费

Variation Reduction减少偏差

Kaizen Mechanism改善方法

1. All employees with SGA (Small Group Activities) System全员参与小组活动
2. Kaizen Week (or Kaizen Blitz)改善周或快速改善系列活动

As part of a Six Sigma project by Black Belt or Green Belt六西格玛黑带或绿带的小组活动

Kaizen Methodologies 改善方法论

Setup the Lean House by all means of Kaizen, especially utilizing the VSM tool通过改善的各个工具,尤其是价值流程图分析的方法建立精益小屋

DMAIC Methodologies (Define, Measure, Analyze, Improve and Control)通过DMAIC方法衡量各项指标

Advantages特点

Speed快速

Rigorous严格精确

Table 1: Comparison summary between Lean and Six Sigma 精益生产和六西格玛的比较

Table 1 shows a comparison summary between Lean and Six Sigma; the common element for both systems is a management system aimed at long term business survival by making more profit. Both techniques differ in their key focus or philosophies that of lean being on waste reduction and Six Sigma’s on reduction in process variation.
由上表可见两者都需要以企业生存和持续盈利为长期目标作为推行的基础。从具体工具的使用可以看出精益生产更侧重消除浪费,而六西格玛则强调消除缺陷。

Lean Sigma, as the synergization of 2 systems, with aspects favorable to improving speed and also rigorous, has advantages over and above the pure systems themselves.
精益六西格玛,作为精益生产和六西格玛的整合,结合了两者在改善速度和变量控制的优点,效用超过了其中的任何一种系统。

The emergence of Toyota as the most profitable car manufacturing company in the world reveals the vitality of the Lean system; indeed the system has been widely emulated since the publication of “The Machine That Changed the World” in 1990. However, one of the key factors for Toyota success that is always overlooked is Quality.
世界上最赚钱的汽车生产商丰田公司的出现使精益生产系统出现在世人面前。自从《改变世界的机器》这本书问世后,世界范围内刮起了一股学习的热潮。然而,在丰田成功的关键要素中,质量要素却总是被忽视。

Toyota initiated TQC (Total Quality Control) in 1961 and won the Deming Award in 1965. The major focus points for Toyota TQC are:
丰田在1961年创立了全面质量控制方法,并于4年后获得戴明奖。该方法主要包括如下几点:

  • Quality First thinking质量第一
  • Kanban (Pull System) thinking看板(拉动系统)管理
  • Continuous Improvement thinking持续改善管理
  • Looking for root causes by asking 5 Whys通过自问5W1H寻找问题根源
  • Fact and data driven事实与数据为基础
  • Operation classification and improvement操作工作的衡量和改善
  • Encourage everyone to do Kaizen (Established Kaizen Mechanism QCC (Quality
  • Control Cycle))鼓励全员参与改善工作(建立品管圈机制)

Toyota did not make the winning of Deming Awards its final goal but rather the starting point of its quality journey. Today, more than 700 statisticians, either PhD or Masters Holders, work in Toyota plants. The interesting point here and the key leverage of Toyota’s success in my opinion in this TQC system, is QCC *1 activities. This is still practiced in Toyota today, and is responsible for most of the best suggestions and ideas for Toyota, resulting in billions of savings to the Toyota group of companies.
丰田最初并没有把获得戴明奖作为他们的目标。而今天,超过700名博士或大师级别的统计学家供职于丰田。我个人认为这其中的奥妙在于丰田推行全员质量维护所带来的影响力,比如质量维护循环活动。而这个方法在丰田还是一如既往得到推行,也借此每天得到最有效的建议和想法,从而给企业带来百万计的节约。

The fundamentals of quality system are Quality Policy and Continuous Improvement. Quality Policy leads the entire organization in one direction, and the Continuous Improvement mechanism focuses on achieving the quality objective by all possible means. Six Sigma with statistical tools is valuable for quality improvement and together with the Six Sigma vision of “Customer Loyalty” and 3.4 dppm quality goals forms an effective company quality policy.
丰田质量体系的支柱是质量政策和持续改善活动。质量政策使整个企业都往同一个方向努力,而持续改善活动则通过各种方法保证质量目标的实现。六西格玛的数据分析工具对提高质量工作是相当有效的,而且通过用户至上的原则和每百万产品3.4件残次品的标准可以有效建立全员质量意识。

Additionally, another advantage of Lean Sigma is the combination of the Kaizen mechanism. Besides the Lean Sigma GB and BB project execution, SGA (Small Group Activities) is crucial to drive for improvement, and since the SGA involves line staff operators, the changes to operations should face least resistances from the shop floor staff. SGA, with other objectives, can be a good follow-up mechanism to strengthen the results from a Lean Sigma project. This will help to ensure the sustainability of results after the project’s closing. For example, following on the process improvements achieved through a Lean Sigma DMAIC project, an SGA team headed by the line leader can be setup to ensure that work standardization is followed and further propagandize the good practice to others.
再者,精益西格玛是各种改善方法的整合。在六西格玛黑带绿带的教育过程中,小组活动尤其重要。小组活动的成员往往由一线操作工组成,而操作工作上的任何变化都需要面对来自基层人员的抵触。小组活动可以作为精益西格玛的重要补充和加固,从而完成预期的各种目标。举例而言,在推行精益六西格玛DMAIC的过程中,小组活动的组长可以确保整个流程标准化作业的有效实施,并把优秀实践推广到其他小组。

In Six Sigma DMAIC methodologies the basic principle is to derive the solutions from the problems in Improve Phase, such as process optimization by DOE (Design of Experiments). If you look at Lean tools in more detail, you will see that in fact some of the Lean tools are solutions based. For example in order to improve inventory JIT is a good solution; in order to improve the quality, work standardization and TPM (Total Productive Maintenance) might be the choices. Of course, TPM can also solve the machine utilization problems too. Consequently, placing Lean Tools in Improve Phase *2 will enrich the solution selection for project leaders, which will increase the project success rate by achieving more improvement targets.
在DMAIC实施过程中,最基本的要素就是获得改善环节中的解决方法,比如DOE的优化。如果你留意一下精益工具的细节,就会发现它们本身也是解决问题的方法。比如为了降低库存,准时化生产是一个好方法。为了提高质量,标准化作业和全员生产力维护是有效的选择。当然,全员生产力维护还能有效降低设备故障率。因此,在六西格玛的实施环节加入精益工具能够使项目组长的工作有效增值,当然也能获得更多额外收益。

7 wastes analysis as well as Value Stream Mapping is helpful to educate in Analyze Phase. Nevertheless, the 5S, Visual Management and Standardize Work are also of value for training in Control Phase *3. All of these have enriched the powers of trained experts to drive for better solutions to the problems.
7大浪费分析和价值流程图分析一样,能够在六西格玛的分析环节加以使用。然而,5S、可视化管理、标准化作业都可以用于六西格玛控制模块的应用。所有这些工具都能有效提高被培训人员的执行能力,使其更好地解决生产现场的问题。

Last but not least, in project management contexts not all of the problems are best solved with DMAIC methodologies since it takes time and needs experts of high caliber. Simple and urgent problems like improving productivity in one cell, local quality improvement, corrective actions to deteriorating processes, can all be addressed by an SGA team. Lean Sigma DMAIC *4 should look for bigger problems such as inventory reduction across stations or functions, improving supply chain systems, entire plant machine utilization improvement, quality system set-up etc.
最后一点,也是必不可少的一点。在整个项目管理的内容中,并不是所有问题都使用于DMAIC方法,因为DMAIC更需要时间和参与人员的专业水平。某个单元的生产水平提升、即时质量提高、纠错活动等都可以作为小组活动的一部分。精益六西格玛四个阶段需要寻找更大的问题,比如功能性库存降低、供应链优化、全厂设备使用率、质量系统建立等。

That are many more advantages to the Lean Sigma management system however it is not the purpose of this paper to discuss all of these in detail, but simply to introduce and emphasize the key concepts of the Lean Sigma management system to the audience. In the future I can foresee a more critical and important role for the Lean Sigma management system in manufacturing industry, especially in China, as it reaches the turning point of transformation from the largest to the strongest manufacturing country.
以上是推行精益六西格玛的一些好处,但是这些并不能简单地纸上谈兵。培训的价值之一是建立大家对精益六西格玛的深入理解。我认为今后精益六西格玛在生产行业将会发挥更重要的作用,尤其是在转型阶段的中国。

Key Notes关键词:

  1. Today QCC has a different name, SGA (Small Group Activities). 如今品管圈有了不同的名字,即小组活动。
  2. I have renamed the Improve Phase as Solution Phase for Lean Sigma System. 我已经将改善环节重新命名为精益西格玛的择决阶段。
  3. I have renamed the Control Phase as Standardization Phase for Lean Sigma System. 我已经将控制环节重新命名为精益西格玛的标准化阶段。
  4. I have renamed the DMAIC as DMASS methodologies for Lean Sigma System. 我已经将DMAIC方法重新命名为精六西格玛的DMASS方法。

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