Molds are built through two main methods: standard machining and EDM. Standard Machining, in its conventional form, has historically been the method of building injection molds. 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) or spark erosion process has become widely used in mold making. As well as allowing the formation of shapes which are difficult to machine, the process allows pre-hardened molds to be shaped so that no heat treatment is required. Changes to a hardened mold 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.

Related posts:

1. Mold Making: Tool steel
2. Machining Technique: High-Performance Milling with a Tool Engagement Controlled CAM System
3. China Mold Making and Molding Services
4. Simple Steps To Lean Mold Making
5. LONG FIBER COMPOUNDS MOLDING GUIDELINES: Minimizing Wear in Processing Equipment
6. Plastic Injection Mold
7. The Cost of Mold Making
8. Canon shares its mold-making experience with outside companies
9. Mold design guideline: Mold construction
10. Small Breakthroughs: Seeing the Bigger Picture at Innovative Mold