Experiments were carried out on 1 mm thick case hardened
steel (18CrNi8) flat plates. A 3D optical measurement
system was used to obtain hole diameter (exit and entry),
taper, and position. The main specifications of the measurement
equipment are shown in Table 1.
Polymer forms (impressions) of the holes were made and
these forms were measured using the 3D optical measurement
system. The advantage of the impression technique is
that a 3D physical model of the hole can be produced and
measured. It is a non-destructive method of measurement.
Impressions can be made repeatably to within 1 m of each
other for hole diameters as small as 80 m in diameter and
1 mm in length [5].