Page 8 - Summer 2024

EDM Today Magazine
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EDM Today Magazine Need answers for the toughest EDM questions?

You’ve come to the right place!

active virgin aluminum surface resulting from the EDM
process can undergo oxidation during an EDM process
undertaken with water dielectric. It is common for this
surface oxide to be non-conductive as EDM’ing with
water releases oxygen which oxidizes the newly creat-
ed surface. This surface condition can be problematic
Virgin vs Regenerated Resin for subsequent EDM operations as follows:
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What are the differences between regenerated and
Wire EDM from a Small Hole EDM’d start hole:
virgin resin?
• You may have diffi culty picking up the hole.
- Dan
• You may not be able to start the cut from the hole.
Roger Kern’s reply:
The remedy for both these situations is to either clean
out the hole with a drill or reamer, or, in the case of very
There are those who insist that virgin resin gives purer
small holes, to clean out the hole with a needle lap.
outlet water, has greater capacity, and has better pH
control than regenerated resin. Let’s examine each of
these claims:
• In the time interval between when the wire breaks
• Water Quality – Water quality is directly related to Restarting a Wire EDM cut after a wire break:

and when you recommence the burn after

the number of active ionic sites imparted to each
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re-threading the wire, the cut surface can oxidize,
bead as a result of the chemical processing of

resulting insulating in a non-conducting surface
the resin beads. Since the process of regeneration

that prevents the re-establishment of the burn.
is similar to that used in making new resin, the care

taken in the processing will have a direct effect on

Unfortunately, there’s no easy solution to this issue.
the water quality produced by either virgin or

If it is possible to run the reverse direction of the

regenerated resin. In fact, some highly regarded
program beginning from the start hole, that may be
domestic virgin resin suppliers purchase low quality

your only solution.
imported virgin resin and then regenerate it to bring

Years ago, it was common practice to reduce the water

it up to USA standards. Thus, the virgin resin you
conductivity to 1 µS when cutting aluminum. This may
purchase may already have been regenerated once,

or may not help your situation.
but, in reality, it makes little difference.

• Capacity - The argument presented previously
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applies here also.
Pickup and Detection Issues with Oxide
Coated Wires
• pH – Deionizing resin is made by immersing highly

porous polystyrene beads in either acid or alkali to
I am testing the new BLACSpark wire on a Mitsubishi

create the active ionic sites that make either anion
FA Series Wire EDM in a medical application, and we

or cation beads. The effects of pH on resin system
are having two issues:

outlet water are strictly related to the care taken
in the rinsing procedures utilized after the chemical

• Pickups are not reliable
processing of the resin beads in either the virgin

• The “wire present” detector is not seeing the wire
resin or regenerated resin manufacturing processes.

- Anonymous Subscriber
If you are utilizing a top quality regeneration house, the
virgin vs regenerated argument doesn’t hold up. Roger Kern’s reply:
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Regarding your fi rst issue: This new type of wire uses
a unique zinc oxide type coating to achieve its re-
markable performance improvement. However, the
Non-conductive Aluminum Surfaces After EDM
zinc oxide coating may not be conductive enough for
I am having issues with getting my Wire EDM to cut
reliable part pickups. This condition is not unique to
from starting holes in my aluminum workpieces that
oxide coated wires, as users of other type coated wires
were put in by my Small Hole EDM. Do you have any
have reported similar issues. This problem is often de-
idea why?
pendent upon which technology your machine uses for
establishing contact detection with the workpiece. For
- Larry
Roger Kern’s reply:
accomplish them by using brass wire for the pickup
operation and then switching to the coated wire for
Oxidation of aluminum surfaces after either Small Hole years, most folks that require highly accurate pickups
the burn.
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EDM and Wire EDM can be an issue since the highly re-
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