Capability Estimation of Geometrical Tolerance With a Material Modifier by a Hasofer–Lind Index

This paper considers a way of measuring a process capability index in order to obtain the geometric tolerance of a pattern of position elements according to the ASME Y14.5 standard. The number of elements present in the pattern, as well as its material condition (least LMC or maximum MMC), are taken into consideration during the analysis. An explicit mathematical model will be developed to identify the distribution functions (PDF and CDF) of defects on the location and diameter. Using these distributions and the Hasofer–Lind index, we will arrive at a new definition of process capability—meaning the value of tolerances that can meet the threshold of x% compliance. Finally, our method is validated using a variety of typical case studies.

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Calculation Method on Process Capability Index of True Position Based on Maximum Material Condition

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.915-916.1456 ◽

2014 ◽

Vol 915-916 ◽

pp. 1456-1459

Author(s):

Shuang Zhang ◽

Jin Gang Gao

Keyword(s):

Calculation Method ◽

Evaluation Method ◽

Process Capability ◽

Process Capability Index ◽

Related Individual ◽

Capability Index ◽

Material Condition ◽

Tolerance Specification ◽

True Position ◽

Capability Evaluation

This paper focuses on process capability evaluation method for position tolerance under maximum material condition. Due to application of maximum material condition the position tolerance specification varies individually for each part, the approach of percentage normalization is introduced to calculate position process capability index. Bush is taken as an example, and true position percentage normalization of 30 parts are calculated. Considering the true position constitution relative to position tolerance at maximum material condition, related individual percentages are used to express the result and the same tolerance size 100% is obtained as for a unilateral tolerance. Process Capability index is calculated with Minitab software.

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Position Tolerance Process Capability Prediction under Maximum Material Condition

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.945-949.107 ◽

2014 ◽

Vol 945-949 ◽

pp. 107-110

Author(s):

Shuang Zhang ◽

Jin Gang Gao ◽

Hua Wang ◽

Xiao Qing Zhang

Keyword(s):

Process Capability ◽

Process Capability Index ◽

Prediction Methods ◽

Related Individual ◽

Capability Index ◽

Material Condition ◽

Tolerance Specification ◽

True Position

Process capability prediction methods for position tolerance under maximum material condition were discussed in this paper. Due to application of maximum material condition the position tolerance specification varied individually for each part, percentage normalization and minimum gap methods were introduced to calculate the position process capability index. Link was taken as an example, true position percentage normalization and minimum gap of 30 parts were calculated. Considering the true position constitution relative to position tolerance at maximum material condition, related individual percentages were used to express the result and the same tolerance size 100% was obtained as for a unilateral tolerance. Set the acceptable value was 0, minimum gap between a hole and a simulated position gauge pin is studied instead of position. The process capability prediction results of two methods were calculated by Minitab software.

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