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About Electrical Discharge Machining
Electrical discharge machining, abbreviated as EDM,
is a tooling method that uses electrical energy to shape and form metal
parts. Electrical discharge machining EDM is one of the most accurate
manufacturing methods of working exceptionally hard metals and other
materials that are difficult to machine cleanly with more conventional
methods. EDM is a process of elimination that erodes or removes metal
and material in the path of electrical discharges that form an arc between
an electrode tool and the work piece until the desired part is attained.
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 and tungsten. This list
is by no means extensive, since this EDM process can be used on many
different metals and compounds.
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. There are two
types of EDM: wire and probe. Wire EDM is used for cutting shapes through
a selected part or assembly. The cutout must have a hole drilled into
it, then the wire is fed through the hole to complete the machining.
Probe 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.
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 is actually generated during the procedure
that would harm the material. Many EDM machines electrodes can rotate
about two-three axis, which is another advantage because it allows for
the cutting of internal cavities.
As well as dimensional factors of size and shape, an important consideration
before undergoing this EDM procedure is the material of the work piece,
since the material of the electrode has to be specially matched. 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.
Featured
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Types of Electrical Discharge Machining
-
is an EDM method that uses rotating electrodes to erode a revolving
workpiece, creating different workpiece shapes by blending the comparative
locations and angular velocities of the workpiece and the electrode.
- uses electrical energy to shape and form metal parts.
- uses a revolving electrically conductive wheel
as the electrode tool for electrical discharge erosion. EDG
is an alternative method for sharpening diamond and carbide tipped
cutting tools, reducing the extreme cost of diamond grinding
wheels.
- is a precise process that uses electrical energy to shape metal parts.
- use a tool electrode to gradually
impress a mirror image of the electrode onto a workpiece.
- is a miniature ram type machine that usually
uses a diamond V-groove to spin the tool electrode up to 10,000 rpm.
Electrode diameters as low as five microns are possible for the production
of micro-holes and other shapes in thin, electrically conductive materials.
- use a tungsten wire electrode that has a diameter as
small as 10µm to machine parts from .1 to 1 mm in size; the size
of these parts makes it impossible to form them through normal semiconductor
processes. These machines use a specially designed wire movement system,
spark generator and monitoring system able to analyze and control extremely
low energy levels.
- removes metal with rapid electrical discharges.
- uses electrical discharges to create microscopic holes.
-
is a common EDM process that removes material with a wire electrode
moving longitudinally through the workpiece. A CNC machine with special
software maintains the movement of the wire electrode relative to the
workpiece.
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