The use of edm tooling started in the 1940s and again the 1960s in order to work with hardened metals. Specifically, one of the original applications was to remove broken drills or taps from aluminum cast parts. The use has evolved beyond the simple repair applications to creating specialized tools, parts, and other items that needed to originate from the hardened metals. Previously, softer metals had to be used because the hardened metals could not be ground or formed to great precision.
The process works by employing electric sparks in a controlled environment that combines electric sparks in dielectric fluid. Original equipment was able to produce up to sixty sparks per second. With upgraded equipment, this has evolved to a near constant stream of hundreds of thousands of sparks per second. The provides an etching sensation because each spark creates a tiny crater in the hardened metals. Using this method, the precision measurements of many critical parts could be made in the much longer lasting metals.
There are many different parts that make up the drilling machine and equipment used to create the precision cuts. An electrode holder needs to be in place to hold the wire or contact in order to create the sparks. Other parts that have been perfected over time include the chuck adapter and holder shank. Together, these various parts make switching parts much easier. Some manufacturers include various kits that come preassembled to perform the various cuts needed.
There are two basic types of edm machines. The sinker edm is submerged in oil or other dielectric fluid. The sparks and locations are controlled by the machine settings and can be controlled on a microsecond level. This is most often used to create 3D shapes. The wire edm uses a single strand of wire instead of an electrode. It is most often used to create punches, tools, or dies that need to be made from hardened metals. These tools are often then used to mill, cut, or shape other softer metals. The wire type is used in scenarios where precision cutting is needed, but large material removal is not required.
The innovation of this type of system has changed how tool and die industries manufacture the parts they sell. The result has been a much higher quality and significantly better precision set of tools made available for many different industries. Many of these tools are used in the manufacture of car parts, heating and cooling, and other areas that affect many peoples lives.