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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.

Blank holder design, set-up and maintenance are crucial for successful stamping of sheet metal parts. Educated spotting as well as adjustment of the appropriate levels of blank holder forces at the different contact areas is a complex process involving the interaction of die design, die making, prototyping and set-up. The response of the part to a blank holder set-up depends on the type of press and the source of blank holder action. A finite difference based microcomputer program CUPDRW will be used to illustrate the effect of the type of blank holder and its set-up on the formability of circular drawn shells. A methodology is also presented in this work for the design of blankholders and its set-up for complex parts formed under drawing conditions. It has been recognized by the industry that control of process and material windows is a prerequisite to the production of quality parts.