Tolerance assignment for production planning 223 it

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Unformatted text preview: ( Fi , i = 1,2,..., n ), parts ( Pj , j = 1,2,..., q ), machines ( M k , k = 1,2,..., r ), etc. The goal of tolerance assignment optimization is to minimize cost subject to process capability constraints and satisfaction of design requirements, i.e. Minimize C = f (ITi , Fi , Pj , M k ), i = 1,2,..., n ; j = 1,2,..., q ; k = 1,2,..., r Subject to : min[IT (Fi )] ≤ ITi ≤ max[IT (Fi )] and Tol SIM ≤ Tol REQ for all design tolerances 220 H. Song et al. where IT (Fi ) is feasible IT for the ith feature; Tol SIM is the stack up simulation results; Tol REQ is the design tolerance requirement. 5.1. Cost model The cost model in this study consists of machine level, part level, and feature level formulations. At the feature level, the cost depends on material machinability, feature type, size, and IT grade. With material, feature type and size as known factors retrieved from design information, the IT grade is the only variable at this level. C (Fi ) = α ⋅ β ⋅ f1 (Fi ) ⋅ V (Fi ) ⋅ exp(a ⋅ ITi ) i = 1,2,..., n where C (Fi ) is the manufacturing cost of the ith feature; α...
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This note was uploaded on 08/03/2010 for the course DD 1234 taught by Professor Zczxc during the Spring '10 term at Magnolia Bible.

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