Page 13 - Fall 2023 EDM Today

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ACC control is especially important for applications in the aerospace or in the medical fi eld, where it must be
guaranteed that the process has been carried out without anomalies.

ACC and ACO must act
continuously on the
parameters. Let us sup-
pose that we found a
magic combination of
parameters valid for this
instant. In the next minute,
the situation changes,
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since the macro and
micro-geometry changes:
we erode deeper, the
fl ushing situation is
different, the active part
of the electrode changed,
Fig. 6: Block diagram of the die sinking EDM control
the wire machined part has
a recess, etc.
Fig. 7 illustrates an optimization of
the servo set point COMP and the
off time t off.
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The adaptive control starts from
the safe parameters COMP=20
and off time 500 us, and climbs
the control fi eld. The maximum is
found for COMP=60 and Toff=50 us
(MRR=100 mm3/min). This maxi-
mum is valid only for a brief instant,
since the situation is changing
continuously.

Therefore, several parameters
must be computed in real time,
during the whole machining pro-
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cess. This cannot be done by a
human operator, complex algo-
rithms take care of this.

Fig. 7: A simple two-variables optimization

Even a good algorithm cannot optimize
more than two parameters at a time;
therefore, several algorithms, or control
loops, must act on the process parameters
tion between various algorithms. It is the EDM Today Magazine
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at a time.
Now, it is very diffi cult to guarantee that all
these algorithms work in combination and
not in a chaotic way. It is like having sever-
al sailors on the sailing boat in the storm,
trying independently to set the sails without
a captain. For this reason, modern process
control systems have a computer based
supervisor that takes care of the coordina-

captain of our boat. Fig. 8: Real time process control algorithms
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(Continued on next page)

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EDM Today, Fall 2023 Issue