Page 4 - Spring 2024

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EVALUATE CLAIMS
Wire Swap Testing
This preliminary test is simple, yet very important.
Claims based upon test results from other shops or the
Start by running a job that is representative of your typical
wire manufacturer should be given intense scrutiny.
work with the wire you are currently using without issues.
Any one of the following items can substantially
swap the wire to the wire you want to test. Restart the
infl uence test results:
machine and monitor the cut to see if the machine has a
stable cut and note the cutting speed. If you see little or
• Workpiece material In the middle of the rough cut, stop the machine and
no improvement in cutting speed, it is likely that the
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• Generator technology
sample wire is not going to offer improved performance.
• Pulse shape
• Polarity
If you do see improved performance, run the entire job
• Open gap voltage
with each wire, including threading, roughing, slug cutoff
• Servo voltage
and skims. Be careful to observe the stability of the skim
• Peak current
cuts for the test wire to assure you don’t lose or have
• On time
unstable sparking anywhere on the contour, particularly
• Off time
on small internal and external radii.
• Wire protection strategies and the levels at which

• Geometry protection strategies and the levels at
face fi nish, including looking for skim lines.
which they are engaged
they are engaged Next, examine the test wire workpiece for size and sur-
• Wire speed IMPROVEMENT TESTING
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• Wire tension
PERFO
PERFORMANCE RMANCE
• Dielectric conductivity
IMPROVEMENT TESTING
• Dielectric temperature
• Dielectric ozonation
• Flushing nozzles (type and size) and nozzle position
It is unlikely that the generator technology in your ma-
(sealed/unsealed)

chine is optimized for the test wire, so now you can begin
• Flushing pressure (upper and lower)
to explore its potential for improvements in rough cut
speed. Important note: I don’t recommend altering any
I have both conducted and supervised wire testing for a
multitude of clients over the years and have discovered
that most comparative testing is not conducted with the
As is common with newer technology machines, if
scientifi c rigor that is necessary to achieve meaningful skim cut settings or technology. TECHTIPS
results. INVESTIGATE POSSIBLE TE POSSIBLE your machine has slider bar performance modifi cation
technology, gradually increase the aggressiveness of the
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machine until either the wire breaks, the cut becomes
unstable or no further speed improvement is noted. Be
INVESTIGA
certain to let the machine settle after each small incre-
NEGATIVE CONSEQUENCES
NEGATIVE CONSEQUENCES
mental adjustment. When you’ve reached the optimum
setting, run the entire contour to check for wire breaks.
I have found that sometimes the promised improved
If your machine does not have slider bar technology,
performance comes with unanticipated issues.
you can incrementally decrease servo voltage and off
For example:
or spark mode settings, as these will adversely affect
• Will wire cleanliness issues adversely affect
surface integrity, slot width and surface fi nish. After
machine maintenance and reliability? time. Important note: Do not change on time, peak current
optimizing those settings, you can also try reducing the
• Is power feed contact wear (based upon length of
machine’s wire protection strategies a bit to get a further
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cut and not cutting time) signifi cantly increased?
increase in speed. When you’ve reached the optimum
• Will wire straightness adversely affect threading
setting, run the entire contour to check for wire breaks
reliability?

and clean skimming.
• Is the wire compatible with your machine’s built-in
But you’re not done yet!
annealing/straightening technology?

• Will wire surface fi nish issues adversely affect roller
Now go back and perform the same optimization for the

and belt life?
current wire you have been using. You may be surprised
to fi nd signifi cant improvement in cutting speed, as
machine builders’ technology is very conservative in order
CONDUCT TESTING AT YOUR SHOPT TESTING AT YOUR SHOP
CONDUC
to guarantee reliable cutting.
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The most meaningful testing will be conducted at your
shop, on your equipment and on your specifi c work.
(Continued on next page)
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EDM Today, Spring 2024 Issue