Page 28 - Fall 2024 EDM Today

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Medical Devices

In the medical device industry, the trend toward
“EDM electrodes keep getting smaller, default
laparoscopic surgery demands more intricate devices
tolerances on parts keep getting tighter, and every
that reduce tissue damage to speed up recovery times.
machine shop owner wants the cycle time to be half
EDM operators also report that plastic components
the time it is now. Entegris POCO Materials EDM
are undergoing design changes that require even more
graphite grades continue to be our go-to selection
intricate features in confi ned spaces.
for pushing the limits of what’s possible on a Sinker
EDM machine.”
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Why do Smaller and More Complex
Tom Radke
Electrodes Impact EDM?
Co-owner of Tri-Gemini LLC
It is important to understand how smaller
electrodes impact EDM.
• Power Limitations
Smaller features require a reduction in the electrode’s undersize. This limits the amount of energy that can be used
in Sinker EDM applications. As a result, it becomes more challenging for operators to obtain the correct balance of
speed and accuracy. Metal removal rates begin to slow down as the power parameters of amperage and on-time
are reduced to allow for the proper overcut to achieve dimensional accuracy.

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• Flushing
Sinker EDM produces debris that must be fl ushed
“Proper graphite material selection is a key
away by the dielectric fl uid. Small features make it
factor to success when EDMing detailed cavities
more diffi cult to clear debris from the gap between
and features. EDM of fi ne detailed parts requires
the electrode and the workpiece.
the selection of high quality, fi ner grained graphite
• Feature Polishing
to avert having excessive electrode wear that
will degrade the level of detail and create a
Complex cavities are harder to polish, which means
rougher fi nish.”
to save time and reduce polishing costs. Part
Bill Heyser
requirements often specify a surface fi nish lower
Engineering & I.T. Manager, Graphel Corporation that EDM tools must produce a fi ner fi nish in order
than 18 VDI (32 µinch RA) to be produced by the
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EDM machine.
Right now, new EDM technology helps to
alleviate some of these challenges. For
example, operators can choose very low
amperage and on-time settings with a
focus on achieving a fi ne surface fi nish
and maintaining detail. In addition,
operators can implement rapid jump
features to assist in removing debris.
However, there are further improvements
that can be made by focusing on consid-
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erations such as material selection.

Overcoming Material Limitations

Assessing the fabrication process is
critical for EDM operators looking to
reduce costs and increase throughput
in the face of more stringent customer
requirements. There’s an opportunity to
optimize everything from the types of cutters
to the role of EDM programs, but one of the Figure 3 — Highly Detailed Electrode
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