Page 68 - EDM Today Spring 2025

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Q: I sometimes get wire shavings or fl akes in the upper head by the electrode pin
on my FANUC Robocut iD Series Wire EDM machines. I am sending you a photo of
my upper head that shows this. What causes this?

A: The most likely cause is a damaged or poor quality slide pin. However, to deter-
mine the root cause, it is important to understand whether the buildup that you are
seeing is fl aky or whether it appears to be shavings.
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If it appears to be fl akes, that typically suggests that
you have a bad spool of wire. If the buildup looks like
shavings, then it is likely that something is shaving it.
The most likely culprit is the slide pin. Visually inspect
the slide pin for chips or grooves.
User Photo
It is also important that the PCD is beveled around
the contact surface. I have seen several PCD slide pins
that are square (not beveled) at the contact surface. These will almost always
contribute to shaving. See Figure 1, a photo of a worn and chipped PCD slide pin.
The purpose of the slide pin is to extend the life of your upper electrode – see Figure
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2. It is one of the reasons your upper electrode is much less worn than the lower when
you index your electrodes. If you suspect that your slide pin is causing the shavings,
and don’t have a replacement, you can remove the slide pin. The machine will perform
normally without it, though you may notice a slight increase in the wear of the upper
Figure 1
electrode (it will still be less than the lower electrode).
PCD Slide Pin

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