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Unformatted text preview: ong et al., 2005]. Here the sensitivity is defined as the effect of unit change of an error source on feature variation, holding other error sources unchanged. This information can be used to guide the tolerance assignment as follows. First, a complete sensitivity matrix is constructed to quantify error sources’ effects on each feature variation. Then, for each unsatisfied tolerance requirements, if exists, the corresponding feature and error source as major contributor are identified. Thirdly, all the processes related to the identified error sources are assigned lower IT grades. Lastly, the Monte Carlo simulation needs to be performed to verify the revised tolerance assignment plan. Repeat this procedure until all the tolerance requirements are satisfied. A virtual prismatic workpiece is used to demonstrate this method. The design specifications are shown in Figure 1, with all features and control points numbered. The initial assigned IT grades for all processes are listed in Table III, with setup planning information, including machine t...
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