Summary: | 碩士 === 長庚大學 === 企業管理研究所 === 95 === With regard to the size for distributions of component manufactured, it is very difficult to produce an item which is completely conformed to the design specification. There is always some variations existed in the process, and the variations could make the components shift from the original design. For this reason, designers must set an suitable tolerance for the component.
A tight tolerance usually implies high manufacturing cost. On the other hand, a wide tolerance reduces the manufacturing cost but may considerably lower the product quality level. Thus, determining optimal tolerance involves a trade-off between the level of quality based on functional performance and the costs associated with the tolerance.
In this paper, we think that optimal tolerance must include quality loss, manufacturing costs and rejection costs. It’s assumed the case of normality. We consider the practice will produce the deviation phenomenon in factory's production process and develop deviation mathematics ways to support application of factory. The purpose is the conversion of quality level and cost. It is worth causing expecting the total cost minimizes and delta. Here, delta represents the number of standard deviations at which each specification limit is located from the process mean. It is a goal to make factory lose cost to reach minimum .
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