-8-
The “D” type impact device built into the EMHT40 will provide optimal results for work pieces
with a surface roughness of 2μm.
A work piece should not be tested: 1) If its temperature is above 176
o
F (80
o
C); 2) It is within
a strong magnetic field; or 3) It is less than 0.12 in. (3mm) thick or has a surface-hardened
layer thinner than 0.03 in. (0.8mm).
Work pieces weighing more than 11 lb. (5kg) require no support.
Work pieces weighing between 4.4 and 11 lb. (2 and 5kg), as well as work pieces with
protruding parts or thin walls, should be anchored to a solid support to prevent them from
moving or flexing as a result of testing.
Work pieces weighing less than 4.4 lb. (2kg) should be tightly attached to a non-yielding
support such as a heavy base plate.
Work pieces with a cylindrical or spherical inside or outside surface radius of less than 1.18 in.
(30mm) require the use of the included support ring or a non-conventional support ring. The
Appendix illustrates and describes several key parameters of 12 support rings in common use.
