Injection Mold Companies use two main methods to manufacture molds: standard machining and EDM. Standard Machining, in its conventional form, has historically been the method of building injection molds with a knee mill. With technological development, CNC machining became the predominant means of making more complex molds with more accurate mold details in less time than traditional methods.
The electrical discharge machining (EDM) spark erosion process has become widely used in mold making. Most injection mold companies have EDM in house, as it is essential to the mold build process of complex molds. EDM allows the formation of injection molded shapes which are difficult to machine, such as square corners or ribs. The process allows pre-hardened molds to be shaped so that no heat treatment is required. Changes to a hardened injection molds by conventional drilling and milling normally require annealing to soften the steel, followed by heat treatment to harden it again. EDM is a simple process in which a shaped electrode, usually made of copper or graphite, is very slowly lowered onto the mold surface (over a period of many hours), which is immersed in paraffin oil. A voltage applied between tool and mold causes spark erosion of the mold surface in the inverse shape of the electrode.
The article comes from China injection mold manufacturer - Mold Best Assurance Company Limited, website is www.mbamoldanddesign.com
