Fall 1996
Micro-Electrodischarge Machining
One of the limitations of PCM is that minimum hole
diameter (0 MIN) depends on the thickness (T) of the
material being etched and in general, 0 MIN=l.IT for
standard applications (Ref. 1).
However there is an increasing number of applications
now requiring high aspect-ratio holes in sheet
and foil materials where a hole diameter (0) may be
0.1T – 0.2T and where 0 may be of the order of 10-100
um. Thus the industrial requirement may be a 40 um
diameter hole in a 100 um foil – an aspect ratio of 2.5 which is impossible to achieve by conventional (isotropic)
PCM of multicrystalline metals and alloys.
For the past six years, research at Cranfield has been
directed at making arrays of such holes for ink jet printing
applications. The work has been supported by a local
company to the extent that Cranfield now has its
own Charmilles micro-electrodischarge machining (~EDM)
centre comprising two NC machines. One is responsible
for fabricating the micro-electrode and the
second one is used to fabricate the holes.
Dr. David Allen, Cranfield University