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Smooth program speeds rough machining.

Baby expensive high-efficiency milling tools? That's what you may be doing if you use traditional software to drive NC machining centers or milling machines. That's why many mold shops find their new CAD/CAM systems can't cut mold surfaces in steel in reasonable time.

Cimlinc Inc, Itasca, IL, now offers a solution. As part of its Unix-based Cim Cut automated NC programming software for sculptured surfaces, the firm offers a roughing module for injection molds, models, tooling aids, and fixtures. Says Jeanne Naysmith, Cimlinc director of advanced manufacturing, "Roughing-not finishing-has always been the key to mold-making productivity with CAD/CAM and NC, so we've extended our Cim Cut gouge-free machining technology to hogging out excess metal. The module gives the programming power and reliability to cut steel directly, eliminating slower indirect methods using copy mills, and does roughing and finishing of any collection of mold surfaces, even if they are untrimmed, unconnected, or overlapping. Areas to be machined away are specified simply with boundary windows and start-and-stop depths. Islands, pockets, and the degree of surface complexity pose no special problems."

Mold makers now can do away with wood and plastic models and duplicating casts, cutting weeks from the design-to-manufacturing cycle. Beta-test users report programming-productivity gains up to 20:1 or better.

Cim Cut's software for finish machining creates parallel cuts straight across contoured surfaces, efficiently removing the last 0.03" to 0.05" of stock for a uniform surface without gouges. At the beginning of a mold job, however, the machine must remove cubic inches and sometimes cubic feet of excess metal as fast as possible. This requires very different machining practices from those used for finish passes.

Using conventional finishing software for roughing, programmers must identify hundreds of areas to be cleared out, precisely defining each area's boundaries in 3D space. Programming can take several days. The roughing-module's algorithms handle tens of thousands of calculations for resolution of surface continuity. Thus, there is less chance for error, and the first program is always good, requiring no intervention by programmer or machine-tool operator. 'Engineers call it Zero Iteration Programming, or ZIP, says Naysmith.

For finish machining, the program creates straight, parallel cuts across the mold's contoured surfaces. In contrast, the roughing-module programs follow surface contours, closely adhering to the industry practice of rough-cutting in 1/8- or 1/4"-deep layers.
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Title Annotation:Manufacturing Solutions
Publication:Tooling & Production
Date:Feb 1, 1992
Previous Article:beyond JIT and TQM lies flow management.
Next Article:CNC screw machine doubles production.

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