Appliance Design - January 2009 - (Page 34)

PLASTICS & PLASTIC PARTS ing users the option of redesigning their parts for standard straight-pull molds or using this more advanced capability. There is, of course, additional cost for side actions and the possibility of flash between the side action face and the rest of the mold. Therefore, side actions are an option with tradeoffs rather than a panacea. closed, as in the illustration, the two mold halves meet in the window. Because the mold faces are drafted at that area, the two mold halves move away from the part (and from one another at the shutoff) as the mold opens and the part is ejected. No part of either mold half is entrapped in the window; therefore, no side action is required. Part designers must keep in mind that the shutoff must be drafted a minimum of 3 degrees. But because the shutoff is angled relative to the wall itself, the draft of the wall must be greater than 3 degrees to allow a 3 degree draft of the shutoff. The required amount of wall draft will vary directly with wall thickness and inversely Eliminating side-actions There are some designs that appear to require side actions but because they are drafted, can be made in simple two-part molds. Take, for example, the part shown in Fig. 10. It would seem that a mold feature protruding inward from the A-Side of the mold or outward from the B-Side would be entrapped in the window when the mold opened. Actually, however, this part can be made in a straight pull mold because the walls are drafted. Fig. 11 shows how this works. In this figure, the yellow area is the part, the green area is the A side of the mold, and the blue area is the B side of the mold. As can be seen, the window on the part can be formed by partially extending both the A and B sides of the mold. When the mold is Fig. 10. Example of a window that appears to require a side action. Membrane Switches and Graphic Overlays for Your Unique Application AD01094DOUG.indd 1 34 applianceDESIGN • Custom design expertise • Single source manufacturing • Precise color matching and repeatability • Assembly of surface mount components/circuit boards/ backplates • Multi-tasking switch pattern designs • Custom molded boxes, bezels and frames with switch installation • Water resistant designs to Nema 4 • 100% function testing of all circuits in-house 9650 Valley View Road Eden Prairie, MN 55344 800-806-6113 • douglascorp.com January 2009 11/19/08 9:34:40 AM www.applianceDESIGN.com http://www.douglascorp.com http://www.douglascorp.com http://www.appliancedesign.com

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Appliance Design - January 2009 Contents Editorial Shipments/Forecasts News Watch Supplier Spotlights Commercial Appliances Plastics & Parts Electronics Motors Design Marts Association Report: NAFEM Advertiser’s Index

Appliance Design - January 2009

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