History has proven that traditionally machining metal in a lathe or mill isn’t always the easiest process. Depending on the type of metal being formed, cutting tools are susceptible to chipping, breaking, or dulling over time. Even the best tools can leave burrs, resulting in additional necessary steps to complete a finished part. Over time, Electrical Discharge Machining (EDM Machining) has eased the process of forming pre-hardened steel or any other conductive metal material. If you don’t already know, this process introduces electricity and removes material by sending an electric current, or spark, through an insulating liquid between two electrodes — a conductive cutting tool and a conductive workpiece. The two parts will never touch, but the spark between them basically melts away any unwanted metal.
There are two types of EDM machining and at Overton Industries both play an integral role in our precision machining capabilities. Our inventory includes 2 Sinker EDM Machines and 5 Wire EDM machines. Let’s take a deeper dive into both types and see why we should be your next stop for any electrical discharge machining needs.
Sinker EDM Machining
Discovered in the 1940s, sinker EDM machining was the first form of machining to introduce an electric current. It was initially discovered by accident, but has since proven to be very valuable when cutting intricate detailing into thick, hardened steel. A sinker EDM uses a formed tool, typically made of graphite, that is “sunk” into a workpiece. The formed tool and workpiece are each connected to a power source and the resulting spark between them creates a pre-programmed cavity within the workpiece.
Most times sinker EDMs only do surface forming and will not pass through the entire piece being machined. This process is most often used when forming contours or cavities on a single axis in pre-hardened steel. Overton Industries’ 2 Sinker EDM Machines include a Charmilles RoboForm CNC Ram EDM and an Ingersol 800 Gantry CNC Ram EDM, with a capacity of up to 21” X 33” X 17”.
Wire EDM Machining
Wire EDM machining was introduced in the 1960s specifically to create tools out of hardened steel. While this process also uses an electric current to cut pre-programmed forms into metal through an insulating fluid, its conductive cutting tool is a brass wire instead of a graphite formed shape. As the brass wire cuts, it continually passes through the workpiece between two spools to prevent wire deterioration in any one spot.
Where a sinker EDM is limited to movement on a single plane, a wire EDM can move through a workpiece along multiple planes, allowing for much more flexibility and range of capability. Wire EDM machining is typically used for detailed finishing and incredibly intricate, tight tolerances up to +/-.0001. Our inventory of Wire EDMs includes five Mitsubishi machines – an FA20S, FA10S, FX10K, MV1200R, and MV2400R, with a capacity of up to 21” X 33” X 17”. We also have an Agie EDM AgieDrill on-site, that creates the initial hole through which the copper is fed for wire forming.
At Overton Industries, both types of electrical discharge machining play an integral role in our precision machining capabilities. As previously discussed, both types of machines cut without any surface-to-surface contact, creating an uncompromised surface finish regardless of material thickness. Fewer post-cutting finishing processes and the fact that these machines are capable of running for hours unattended will also reduce overall labor costs on any project. If you’re still not convinced that electrical discharge machining is the missing piece to your current manufacturing process puzzle, give us a call today. EDM once and we guarantee you’ll never go back.