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Surface defects occur during forming, material unloading and during further material processing. During forming operations the compressive forming stresses are the cause of defects. During material unloading and further material processing, springback and residual stresses are the major cause of such defects. The conditions for the occurrence of surface defects at these three stages are examined and discussed. A computer aided methodology is presented for estimation of the residual stresses, application of the approach is given for some practical examples.

A simultaneous Design/Process/Material engineering approach for the analysis of automotive structural cross member designs is presented. It is shown that it is possible at the product design stages to evaluate i. forming severity, ii. blank shape and nestability, iii. spotting requirements, and iv. structural analysis based on yield stress and thickness distributions after forming. The approach allows the reduction of material content in the part (by nesting and possible weight reduction), a better estimate of part performance during stamping, the evaluation of the effect of the material properties, the construction of the blanking die at the same time as production form tooling, and the reduction of a significant portion of the product design/manufacturing cycle. A production cross member is used to validate the approach. The production cross member information also served as a basis for a new prototype cross member.

Blank development is the basis for calculating the material cost and hence the product cost, at the quoting stage. Understanding the metal flow under the binder is a critical activity during the tooling design stages, as well as during phototyping. The paper describes a computer aided blank development and metal flow analysis system, that will assist in performing the functions described above, before the tools are built, for box shaped parts drawn in multi-stage forming operations with a flat punch face, and a flat binder. Development of the minimum blank shape, using the SLF technique for shrink flanged components is not new. The paper addresses the extension of the approach to: i. multi-stage forming operations and, ii. the incorporation of the effect of thickness changes on the blank shape. Applications are given in the paper using the computer program BLANKDEV.