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Swiss Tech Precision, USA
690 S. Clearwater Loop, Post Falls, ID 83854 P: 208.773.4800 F: 208.773.4882
Swiss Tech Precision has a full spectrum of Wire and Sinker EDM Capabilities.
In wire electrical discharge machining (WEDM), also known as wire-cut EDM, a thin, single-strand metal wire, usually brass, is fed through the work piece while submerged in a tank of dielectric fluid, typically deionized water. Wire-cut EDM is used to cut plates as thick as 300mm and to make punches, tools, and dies from hard metals that are difficult to machine with other methods. The wire, which is constantly fed from a spool, is held between upper and lower diamond guides. The guides are CNC-controlled, and move in the x–y plane. The upper guide can also move independently in the z–u–v axis, allowing the ability to cut tapered and transitioning shapes (circle on the bottom, square at the top for example). The upper guide can control axis movements in x–y–u–v–i–j–k–l–. This allows the wire-cut EDM to be programmed to cut very intricate and delicate shapes. The upper and lower diamond guides are usually accurate to 0.004 mm, and can have a cutting path as small as 0.021 mm using Ø 0.02 mm wire, though the average cutting path that achieves the best economic cost and machining time is 0.335 mm using Ø 0.25 brass wire.
Sinker EDM, also called cavity type EDM or volume EDM, consists of an electrode and work piece submerged in an insulating liquid such as, more typically, oil or, less frequently, other dielectric fluids. The electrode and work piece are connected to a power supply. The power supply generates an electrical potential between the two parts. As the electrode approaches the work piece, dielectric breakdown occurs in the fluid, forming a plasma channel, and a small spark jumps.
The on time setting determines the length or duration of the spark. Hence, a longer on time produces a deeper cavity for that spark and all subsequent sparks for that cycle, creating a rougher finish on the work piece. The reverse is true for a shorter on time. Off time is the period of time that one spark is replaced by another. A longer off time, for example, allows the flushing of dielectric fluid through a nozzle to clean out the eroded debris, thereby avoiding a short circuit. These settings can be maintained in microseconds. The typical part geometry is a complex 3D shape, often with small or odd shaped angles.
The EDM process is most widely used by the die industries, and is a common method of making prototype and production parts, especially in the aerospace, automobile and electronics industries in which production quantities are relatively low. In sinker EDM, a graphite, copper tungsten or pure copper electrode is machined into the desired (negative) shape and fed into the work piece on the end of a vertical ram.