HEIDENHAIN TNC 406 - Manual (Page 88)

HEIDENHAIN TNC 406, TNC 416 67
4.7 P
ar
amet
ers in the Er
osion T
able
Wear rate WR
The wear rate is the ratio between the volume of material removed
from an electrode (Ve) and the volume of material removed from the
workpiece (Vw).
WR = Ve / Vw • 100 %
For the wear rate on the electrode for your particular machining task
and combination of materials, refer to the electrode table.
Surface finish RA
Surface finish is a measure of machining quality. A machined surface
is never absolutely smooth, but consists of a series of peaks and
valleys.
Maximum surface roughness R
max
The maximum surface roughness Rmax is the difference in height
between the highest peak and the lowest valley.
The maximum surface roughness Rmax is also calculated from the
width of the two-times gap 2G and the minimum undersize UNS as
follows:
R
max
= 0.5 • ( UNS – 2G )
Determining surface finish RA according to VDI 3400
1 Determine the centerline of R
max
2 Measure all peaks and valleys from the centerline
3 Add the measured values together and divide by the number of
measured values. The result is the surface finish RA in [µm]
Ve
Vw
Rmax
RA
R2 R3 R4
min Rn R1
max