fluid. If cavitation within the hole can be
minimised then the coefficient of discharge of the hole will
not reduce.
vapour
The work presented in this paper has shown that a significant
improvement has been achieved in hole quality and
hole form as Fig. 7 shows compared to Fig. 5. The results
have also shown that the technique allows a range of tapers
to be produced with hole diameters from ∼100 to 250 m.
Tapered holes with k-factor values of k = 6.5, have been produced.
A high quality of hole roundness has been achieved
(2–3 m). SEM images show the typical surface quality
achieved with EDM with R
values of ∼0.3 m(Fig. 8).
The repeatability of the hole form, taper and diameter difference
along the hole length is clearly shown in the plot in
Fig. 11.
a
This technique has been successfully tested in an indus-
trial environment and it can be applied in any industry where
micro-EDM hole drilling is used and where there is a need
for an improvement in the hole quality and reverse tapered
holes. The solution can be easily adapted to fit an existing
system and the results have shown that the solution is stable
and repeatable