product quality traced in many cases to decisions made by engineers when

Product quality traced in many cases to decisions

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product quality traced in many cases to decisions made by engineers when designing component parts. Traditionally, design engineers used the ―three - sigma‖ rule when evaluat ing whether or not an acceptable proportion of manufactured components would be supposed to meet tolerances. When a component’s tolerances were consistent with a spread of six standard deviation units of process variation, about 99.7 percent of the components for a centered process would be expected to conform to tolerances. That is, only 0.3 percent of parts would be nonconforming to tolerances, which means that to3,000 defected parts per mil-lion (DPPM),(Arnheiter and Maleyeff,2005). The six sigma started by Motorola was the first company to launch a six sigma approach in the mid-1980sIn 1988, where the Motorola specialized in electronic products, Bill Smith1986 is engineer and statistician at Motorola, introduce the six sig-ma concept aiming to attack the existing quality problems in the company. Motorola received the Malcolm Baldrige National Quality Award, which led to an increased interest of six sigma in other organizations, see Pyzdek (2001). Today, a number of global organizations have developed six sigma approach of their own and six sigma is now established in almost every industry. (Andersson, et al 2006). At Motorola, when studying the relationship between the quality of component and the quality of final product it was discovered that, from lot-to-lot, a process tended to shift a maximum of 1.5 sigma units (McFadden, 1993). This concept is shown graphically in next Figure, which shows a centered process and processes, shifted 1.5 sigma units in both directions. Table provides the relationship between component quality and finalproduct quality, assuming that the full 1.5 sigma shift takes place. In next Table, Sigma level is the standardized process variation (see Figure), OFD quality is the NCPPM if the process shifts a full 1.5 sigma units, and the probabilities in the
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ISSN: 2349-5677 Volume 1, Issue 6, November 2014 106 table provide the proportion of final products that will be free of defects. For example, if the company sets a goal for final product quality of 99.7 percent and prod-ucts include about 1,000 OFDs, then the 3.4 DPPM corresponding to the Six-Sigma methodology would became the standard against which all decisions were made,(Arnheiter and Maleyeff,2005). Fig.2 Process average shifting+/-1.5 Sigma units Tab.1Final product quality level (percentage conforming) Six Sigma was started and developed at Motorola by an engineer Bill Smith in the mid- 1980s.Six Sigma is credited with playing a major role in the turnaround Motorola accomplished
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ISSN: 2349-5677 Volume 1, Issue 6, November 2014 107 in their quality at the time culminating in Motorola winning the 1988 Balding National Quality Award.(Snee, 2010) Six sigma established the power implementation and Sig-nificant deployments lead by the chief executive officers (CEOs) at AlliedSignal and general electric (GE) was the next major step for the approach. Welch promoted Six Sigma aggressively inside and outside GE. The initiative established major usage across business and industry; first in the USA and then globally. Most
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