What is Sinker EDM?
Sinker EDM, employs machined electrodes of varying shapes, sizes and materials to remove material from the workpiece.
Electrodes are usually made from graphite, but copper, tungsten or brass as well as combinations of these materials are also used, and the geometric features of the electrode can be customized to reach the required specifications.
In the sinker EDM process, both the workpiece and the electrode are submerged in a dielectric fluid of oil or synthetic oil and the machine guides the electrode toward the workpiece automatically using CNC technology.
As in wire EDM, as the electrode approaches the workpiece, the strength of the electrical charges breaks the barrier of dielectric fluid and a spark is created, eroding away a small amount of material by melting and vaporizing microscopic particles. The process repeats hundreds of thousands of times per second, and as material is removed, the machine continues to direct the movement of the electrode until the desired dimensions are achieved.
After the initial “roughing” pass, during which the bulk of the material is removed, we may perform additional 3-D orbiting passes in order to achieve the best surface finish and tightest tolerances possible.
Sinker EDM allows us to machine complex 3-D shapes, blind cavities, intricate internal features, threads into hardened parts, and much more. In addition, sinker EDM has the ability to use multi-up electrodes for multi-up parts production.
Sinker EDM, also called cavity type EDM or volume EDM, consists of an electrode and workpiece submerged in an insulating liquid such as, more typically,oil or, less frequently, other dielectric fluids. The electrode and workpiece are connected to a suitable power supply. The power supply generates an electrical potential between the two parts. As the electrode approaches the workpiece, dielectric breakdown occurs in the fluid, forming a plasma channel and a small spark jumps.