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"Close enough" no longer good enough.

Time was when a good pattern made a good casting and everyone was satisfied. But foundrymen attending the pattern sessions at the 1991 Casting Congress came away with the realization that the need and ability to make superior patterns to manufacture superior castings has indeed arrived.

According to John Mcintyre of Anderson Pattern Works, Muskegon, Michigan, this premise begins with a foundry's commitment to quality control. A good quality control (QC) program is the cornerstone to total foundry productivity, he said. The blending of both management commitment and a solid QC program can be accelerated with the proper application of technology, but the successful quality system integrates all of a foundry's resources-its people, equipment and procedures. Together, they form a single, strong unit-a team of the best and the brightest managers and production workers who are able to influence others in the organization. When the system is fully implemented, everyone in the organization must feel that the QC effort involves them and that they have a role in its success.

Careful consideration must be given to equipment. Close tolerance tooling and "fast-to-market" demands clearly expose yesterday's pattern making practices and equipment as inefficient by today's competitive standards, he said. He cited three-dimensional, computer-aided design (3D-CAD) as an example of a data system that can eliminate the need for physical modelling. Using 3DCAD, it is possible to construct a wire-frame model that can then be surfaced and tool pathed, providing usable data for numerically controlled machine centers for computer-aided manufacturing (CAM).

Mark Ganter of the Univ. of Washington examined the latest computer-assisted generation of pattern cores from a boundary representation solid model. The system provides an effective technique for both recognizing and extracting internal geometry in the pattern development process. Because the placement of cores and core prints affects the location of the parting surface, the relationship between parting surface and cores holds the key to good mold design.

Cores increase production costs because each core requires a separate pattern and mold; the more cores the greater the mold assembly cost. Therefore, properly identifying beforehand those geometries that require cores has an economic impact that may exceed their impact on the pattern making process itself. Clearly, Ganter said, the use of these techniques could involve process planning, design development, part classification and cost estimation.
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Title Annotation:95th AFS Casting Congress, May 5-9, 1991 - Birmingham, Alabama; A Technical Review: Pattern Division
Publication:Modern Casting
Date:Jun 1, 1991
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