EDM Copper Is Often Best For EDM
Machining The use of edm copper in moldmaking is as old
as EDM%20machining itself. Copper is much more common
than graphite as an electrode material in Europe and
Asia, though this is changing.
Copper has many advantages, as well as many
disadvantages, when compared to graphite as a material for edm
machining. A visit to nearly any EDM department will quickly
reveal that copper is very much a useful material in plastic
injection mold making.
Deciding which material fits your application
is important, and time spent analyzing this can save you many
headaches, not to mention time and money.
What are the advantages of EDM
copper?
-
Copper is more efficiently cut on WEDM
machines, which makes it cut much faster
than graphite in WEDM. Highly detailed electrodes,
which were formerly manufactured on surface grinders,
required many hours of highly skilled labor. The use of
copper and WEDM to produce these electrodes has
dramatically changed EDM%20machining.
-
Copper is less likely to cause pits in the steel
workpiece. The tendency of any electrode to "DC arc" is
the curse of EDM. When the flushing is poor, machining
conditions are ripe for a short circuit to occur in the
EDM process, causing the tell-tale pits in the
workpiece. Copper is much more forgiving and less
likely to DC arc.
-
Copper is usually used to produce a finer finish in the
steel. Copper electrodes are sometimes polished to
reproduce the fine finish on the mold surface. Newer
EDM machines have polishing settings that can produce
mirror finishes, and usually copper is used.
-
Copper is the best for small cavities, especially where
polishing is difficult. Because of it's resistance to
pitting and the finer finishes attainable, copper is
often used in these applications. Adding tungsten to
copper increases it's excellent wear characteristics,
but also is very difficult to machine.
-
Copper can be machined by coining. In this process, the
copper is stamped with an image, just like a coin, and
then used as an EDM electrode. This can be an excellent
application for designs such as logos.
- Copper is clean to machine and leaves no annoying dust.
Also, tellurium copper leaves much less burr than pure
copper.
What kind of EDM copper should be
used?Tellurium copper (Telco) performs the same as pure
copper as an electrode material. It has a huge advantage,
however, because of it's high machinability rating: 90% (free
cutting brass = 100%). Pure copper has a rating of 20%.
Telco EDM copper is highly recommended for
use on machines which have been designed to work best with
copper. Its high machability rating and fast WEDM speeds make
it ideal for highly detailed, difficult to flush
electrodes.
Why is copper more commonly used in Europe
and Asia?This happened for several reasons. When the first
generation of machines were developed in these areas, the power
supplies were R-C, or Resistor Condenser. Metallic electrodes
such copper and brass were the only materials that efficiently
performed in these machines.
Then, as newer generations of machines were
developed, the use of EDM copper was well established.
Plus, EDM grade graphite was simply unavailable. Find out more
here...
The use of copper has declined as technology
has progressed. Newer EDM machines are designed to use graphite
as well as copper. High speed machining centers are equipped
with vacuum environments to remove the annoying graphite dust.
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