EDM Industry Information
EDM, an abbreviation of
electrical discharge machining, is a tooling method that uses electrical energy to cut, drill, etch and machine metal parts. Electrical discharge machines
are one of the most accurate types of machining equipment used in the
manufacturing of hard metals and other materials that are difficult to
machine cleanly with conventional mechanical-cutting methods. EDM
erodes the material in the path of the EDM tool using electrical discharges, or sparks. The "tool electrode" forms an arc to
the "workpiece electrode" as the two are brought closer together,
creating the intense electric field which is responsible for removing
material. EDM is often referred to as spark machining, spark eroding
and die sinking; tooling and machining done on very small scales are
referred to as
micro
EDM.
Wire
EDM (or wire erosion) and
sinker
EDM, also know as
plunge EDM, conventional EDM or
ram EDM, are the two main types of EDM machining.
Small hole EDM is a type of drilling which is also required as a pretreatment for wire EDM.
Some of the common applications for electrical discharge machining
include producing plastic molds, die casting dies from hardened steel
and forging dies. Other purposes include the manufacturing of engine
parts like compressor blades of titanium alloys and nickel based super
alloys. Industries that benefit from the use of the electrical
discharge machining process include food and beverage, automobile,
stamping, extruding, defense, electronics, aerospace and medical. Using
this process is extremely accurate, reliable and affordable, so it is
becoming an increasingly popular choice for many companies. Diverse
materials such as the following can be cut with electrical discharge
machining: aluminum, copper, zinc, bronze, tin, silicon, titanium,
stainless steel, gold, lead, silver, iron, cobalt, nickel, tungsten and
many other compounds, and the preheating of hard metals which is
necessary in mechanical tooling is unnecessary with EDM.
The actual machining is accomplished through sparks, which are
electrical discharges that can generate heat anywhere from eight to
twenty thousand degrees. A shaped tool, electrode or wire is used to
generate the series of sparks, depending on the process. There is no
actual contact between the electrode and the work piece, but rather a
conductive path that is established between the electrode and the
material. This process takes place in a bath of dielectric fluid, which
prevents premature sparking and flushes away debris, conducts
electricity between the electrode and the work piece and then flushes
out the melted material. Sinker, or plunge EDM is capable of boring
holes into metal workpieces,
creating holes, patterns and at times three dimensional objects, while
wire EDM cuts patterns and shapes.
Both wire EDM and sinker EDM use the same general process, including
immersion in dielectric fluid. In order to wire electrical discharge
machine a metal part, a hole or perforation must already be made in the
metal - this is usually done by small hole EDM; a thin brass wire is
fed through the workpiece and clamped on both ends by diamond guides,
then the wire cuts through the metal in a specified pattern guided by
CNC machine arms. Wire EDM is used for cutting shapes through a
selected part or assembly. Sinker EDM is used for more complex
geometries where machined graphite or copper electrodes are used to
erode the desired shape into the part or assembly. CNC machines are
used to guide, monitor and control the electrical discharge machining
process, as well as CAD and CAM software. As well as dimensional
factors of size and shape, an important consideration when using EDM is
the material of the work piece, since the material of the electrode has
to be specially matched.
Electrical discharge machining has advantages over other machining
techniques due to its ability to create complex and intricate parts
with a high degree of accuracy. This process is able to machine hard
materials, where other machining processes would have difficulties.
Another advantage of EDM is its ability to machine parts on an
extremely small scale. While using this process, the work piece is not
deformed from impact because there is no direct contact between the
electrode and the material, and likewise the work piece is burr-free
after completion and saved from heat damage because very little
material-damaging heat is generated during the procedure. Many EDM
machines electrodes can rotate about two-three axis, which is another
advantage because it allows for the cutting of internal cavities.
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EDM and Electrical Discharge
Machining Image Provided by Twin
City EDM |