Rapid hard tooling by plasma spraying for injection molding and sheet metal forming

Amidst the harsh competition over the development of new products around th e world, rapid prototyping, especially rapid tooling methods have received widespread attention. Amongst the rapid hard tooling methods, thermal spray ing can manufacture metal molds without limitation of pattern size. However , it has the disadvantage that only soft metals with low melting points suc h as zinc alloy can be sprayed to original mold, such as a rapid prototypin g model or a natural material pattern, due to their lack of heat resistance and shrinkage of spray metals. So the wear resistance of spray tool is poo r, it can be used only for trial or small-lot production. In this study, at tempts were made to improve the heat resistance by using composite material s made of ceramic and metal powders as the sprayed original mold materials, and using stainless steel, tungsten carbide alloy, iron-nickel-chromium al loy with excellent wear resistance as spraying materials, respectively. The results show that injection molding spray mold and sheet metal forming spr ay die can be made by transferring from natural patterns and rapid prototyp ing models. As the durability and dimensional accuracy of the sprayed tools has sharply improved, the tools can be used for mass production. (C) 2001 Elsevier Science B.V. All rights reserved.