Quality Control Fundamentals质量控制基本原理 Quality质量
Quality has become one of the most important consumer decision factors in the selection among competing products and services. The phenomenon is widespread, regardless of whether the consumer is an individual, an industrial organization, a retail store, a bank or financial institution, or a military defense program. Consequently, understanding and improving quality are key factors leading to business success, growth, and enhanced competitiveness. There is a substantial return on investment from improved quality and from successfully employing quality as an integral part of overall business strategy.
质量是消费者在激烈的产品和服务竞争中进行选择的一个重要因素.不管这个消费者是个人、产业组织、零售店或防务工程,这个想象是普遍存在的.因此,关注并提升质量是取得成功、发展并强化竞争力的关键因素.投资质量的提升并把质量作为经营策略的主要部分将会得到极大地回报.
We may define quality in many ways. Most people have a conceptual
understanding of quality as relating to one or more desirable characteristics that a product or service should possess. Although this conceptual understanding is certainly a useful starting point, we will give a more precise and useful definition.
我们对质量有很多种定义.许多人在观念上把质量理解为产品或服务拥有一个或更多满意的性能.尽管这种概念性理解是有效地,我们将给出更精确、有效地定义.
Quality---- characteristic or property consisting of several well-defined technical and aesthetic, hence subjective, considerations; conformance to design (customer) requirement.
质量-特性或性能中包含几种明确定义的技术的美学的,因此主观考虑；满足设计（顾客）需求. Quality control------detecting poor quality (nonconformance) in manufactured products and taking corrective action to eliminate it.
质量控制-检测在工业产品中检测不合格的质量（不合格品）并采取纠正措施去避免.
The traditional definition of quality is based on the viewpoint that products and services must meet the requirement of those who use them. Therefore, Quality means fitness for use.
传统的质量定义是产品或服务必须满足使用者的需求.因此,质量就是适用度
There are two general aspects of fitness for use: quality of design and quality of conformance.
适用度一般有两个方面:设计质量和一致性的质量。
Quality by design intent refers to the various grades or levels of quality that are intentionally determined by design. All goods and services are produced in various
grades or levels of quality. These variations in grades or levels of quality are
intentional, and, consequently, the appropriate technical term is quality of design.
设计意图的质量指的是设计中故意设计的各种等级或质量等级。所有的商品和服务都是在不同的等级或质量等级中产生的。这些变化的等级或质量水平是故意的，因此，适当的技术术语称之为设计质量。
Quality of conformance refers to how well the product conforms to specifications required by design.
产品质量的一致性是指如何符合规范设计的要求。
Quality of conformance is influenced by a number of factors, including the choice of manufacturing processes, the training and supervision of the workforce, the types of process controls, tests, and inspection activities that are employed, the extent to which these procedures are followed, and the motivation of the workforce to achieve quality.
一致性质量受到很多因素的影响,包括生产流程的选择、员工的培训和监督，所采用的过程控制,测试,和检查活动的类型,这些程序被遵循的程度 ,激励员工来实现质量。
Unfortunately, this definition has become associated more with the
conformance aspect of quality than with design. This is in part due to the lack of formal education most designers and engineers receive in quality
engineering methodology. This also leads to much less focus on the customer and more of a “conformance-to-specifications” approach to quality, regardless of whether the product, even when produced to standards, was actually
“fit-foruse” by the customer. Also, there is still a widespread belief that quality is a problem that can be dealt with solely in manufacturing, or that the only way quality can be improved is by “gold-plating” the product.
不幸的是,相对于设计，这个定义更多的关于质量的一致性。这部分是由于大多数设计师和工程师缺乏质量工程方法的正规教育。这也导致更少地关注客户和更多关注质量与规格一致, 无论产品，即使生产标准，实际上是“适合使用”的客户。同时,普遍仍认为,在生产制造中质量问题完全可以解决, 或者唯一的可以提高质的方式是给产品“镀金”。
We prefer a modern definition of quality: Quality is inversely
proportional to variability. Note that this definition implies that if variability in the important characteristics of a product decreases, the quality of the product increases. As an example of the operational effectiveness of this definition, a few years ago, one of the automobile companies in the United States
performed a comparative study of a transmission that was manufactured in a domestic plant and by a Japanese supplier.
我们倾向于质量的现代定义:质量与变化成反比。请注意,这个定义意味着如果产品的重要特征的变化减少,产品的质量就会提高。举一个这个定义的操作效益的例子,几年前, 美国的一个汽车公司进行了一个在国内工厂制造过程的传输和由日本供应商制造过程的传输的比较研究。
An analysis of warranty claims and repair costs indicated that there was a
striking difference between the two sources of production, with the
Japanese-produced transmission having much lower costs, as shown in Fig. 5.1. As part of the study to discover the cause of this difference in cost and performance, the company selected random samples of transmissions from each plant, disassembled them, and measured several critical quality characteristics.
保修索赔和维修费用的分析表明，两者的生产有着显着的区别，如图5.1所示，日本制造的运输成本很低。这项研究的一部分是发现成本和表现中这种差异的原因，公司从每个工厂随机选择抽样，拆卸样本，并测量了几个关键的质量特性。
Figure 5.2 is generally representative of the results of this study. Note that the distribution of the critical characteristics for the transmissions
manufactured in the United States takes up about 75% of the width of the specifications, implying that very few nonconforming units would be produced. In fact, the plant was producing at a quality level that was quite good, based on the generally accepted view of quality within the company. However, the Japanese plant produced transmissions for which the same critical characteristics take up only about 25% of the specification band. As a result, there is considerably less variability in the critical quality
characteristics of the Japanese-built transmissions in comparison to those built in the United States.
图5.2通常是这项研究的结果的代表。注意的是美国生产传输的临界特征的分布 占宽度规格的75%左右,这意味着不相容的产品很少。事实上, 根据公司内部的质量标准， 工厂生产的质量水平很好,然而,日本工厂的生产传输的相同的临界特征规范只占用约25%的规格带。因此,日本建立的生产传输中的关键质量特征的变化要比美国的少很多。
There are two obvious questions here: Why did the Japanese do this? How did they do this? The answer to the “why” question is obvious from examination of Fig. 5.1. Reduced variability has directly translated into lower costs。Furthermore, the Japanese-built transmissions shifted gears more smoothly, ran more quietly, and were generally perceived by the customer as superior to those built domestically. Fewer repairs and warranty claims means less rework and the reduction of wasted time, effort, and money. Thus, quality truly is inversely proportional to variability.
How did the Japanese do this? The answer lies in the systematic and effective use of the methods described in this text.
这里有两个明显的问题:为什么日本人这样做呢?他们是如何做到这一点呢? 再看图5.1， “为什么”的问题的答案是显而易见的。减少的变化直接转化为低成本。此外,日本造的变速齿轮更顺畅,更安静，客户通常认为日本的变速齿轮要比国内的好。更少的维修和保修索赔意味着很少的返工,节约时间 ,精力,和金钱。因此,质量真的是与变化成反比。日本人是怎么做的呢?答案就在于系统和有效地使用本文中描述的方法。
Dimensions of Quality质量维度
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