Appliance Design - November 2008 - (Page 19)

Phillips built the external housings for the portable speech generating devices from DynaVox Technologies. Magnesium was used because of its durability, lightweight, and inherent shielding properties. Metals & Metal Parts parts that had to be mechanically assembled and replacing them with one fully molded metal part. In one case, a medical device went from a 9-piece assembly to a single-piece assembly. Previously, the parts were made by machining them one at a time and in succeeding operations are assembled using mechanical fasteners. This flexibility is one reason that molding is popular for producing parts no matter what its material composition. A big advantage for metal injection molding, is the sheer number of materials with which it can work. The most commonly used elements in metal injection molding processing are iron, nickel, chromium, and molybdenum. Iron and nickel are two of the easiest elements to process because of their compatible melt temperature and ease of sintering. While density rates can vary by material, metal injection molded parts on average are not as dense as with the magnesium process. With metal injection molding, the part can be between 94 and 99 percent dense. This can be improved through a secondary process called “hipping,” or a hot isostatic process, in which the part is placed in a large pressure vehicle, heated to near melt and subjected to extremely high pressures to compress out remaining voids. The magnesium process makes parts that are about 100 percent dense right out of the molding machine. With the Thixotropic process there are no voids as with the metal injection molding process. Magnesium chips are heated to get the material to a thixotropic state, which is a gel-like consistency that becomes more fluid under force or pressure. Unlike die-casting, it does not require the handling of molten metals in a separate melting and transfer system. While in this gel-like state, the material flows into the tooling cavity for molding. The tooling is similar in cost and construction to plastic injection or die-cast tooling and lifters, slides and other actions can be designed into the tooling, says LeBeau. Pelke says that this technology is a good solution for companies looking to migrate www.applianceDesIGN.com AD09081Ven1.indd 1 applianceDesIGN November 2008 19 AM 8/5/08 11:55:49 http://www.ventronicsinc.com http://www.ventronicsinc.com http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - November 2008

Appliance Design - November 2008 Contents Editorial Shipments/Forecasts News Watch Metals & Metal Parts Gas Technology Displays Quality & Standards New Products Design Marts Association Report: AHAM Advertiser's Index

Appliance Design - November 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.