Cylindrical Samples - BAQ kaloMAX Manual

BAQ kaloMAX
The total penetration depth of the ball is:

2
D
2
T = R
R
4
The depth of penetration in the base material is:

2
d
2
t= R R
4
The thickness of the layer results from the difference:
h=T t
 
2
d
2
h= R R
4
If the layer is very thin and the spherical cap is ground into the base material only a little, the
diameters D and d are very small compared to the radius of the ball. In this case the equation
can be simplified to:
2 2
D d
h=
8R
This formula shows, that the accuracy of layer thickness measurement by means of spherical
cap grinding depends on the accurate measurement of the two diameter D and d, because the
error of R is less then 1 ‰. Furthermore the meticulous measurement of the two diameters is
important because the square of these items is used in the calculation. In general, the spherical
cap should not be ground too deep into the base material in order to achieve high accuracy.

6.2 Cylindrical samples

When the sample is cylindrical, the shape of the spherical cap is elliptic instead of circular. The
calculation of layer thickness can be done with the same equations as for plane samples but it
is essential to take D and d from the longitudinal axis of the ellipse.
2
D
2
4
Manual
Page 10