EDM Vs. Milling For Die And Mold Machining

Traditionally, choosing how to approach a workpiece was relatively straightforward. Choosing between EDM and milling is becoming more difficult in a lot of die and mold shops. There seem to be new rules, making the choice complicated. Here is when it makes sense to use each respective process:

EDM

• Inside corners - EDM is effective on inside corners, particularly those with a sharp angle.
• Complex geometric shapes - the more twists, turns, sides, and edges, the better off you will be using EDM over milling.
• Deep cuts - if your project requires deep cutting (where your tool is significantly longer than it is wide) then EDM is your best bet.
• Unattended cutting - it is easy to automate EDM due to its predictable pattern. Using robots and electrodes to cut workpieces, EDM can work 24/7 with minimal attention needed.
• Parts requiring specialized knowledge - computer programs can often cut much quicker due to electrodes. 

Milling

• Select surfaces - textures that are not cosmetic or those that will be textured are made easier with milling because EDM often adds another step to the process. This is due to the polishing required with EDM before you can texture.
• Easy access - feel free to use milling whenever the geometry of the workpiece is pretty open and not very deep.
• Grouped parts - for workpieces that are similar (also called "family" parts) or pieces that have multiple cavities, you can get more value out of your time spent on figuring out how to mill them. Once you have the milling down for one piece, it is simple and fast to scale up your plans to the rest.
• Parts that restrict the use of an HAZ.
• When ultra-high accuracy is needed - milling adheres to strict tolerances. EDM accuracy reduces as you approach a finished surface due to the tolerance stacking of the electrodes. 

Sometimes, despite the different benefits of each method, it comes down to which machine is open or which employees are available to program or work them. In fact, programming is an increasingly important factor in the debate about EDM vs. milling. Your team's ability to maintain efficiencies of scale while implementing applications that achieve the desired level of accuracy will be key in determining whether or not EDM is a viable alternative to traditional milling. Each workpiece is different, so be sure to review each project individually and make the most informed decision. Contact local professionals, such as those from Tri-State Fabricators Inc, for further assistance.