11
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Curved surface: The best testing surface of sample is flat. When the curvature radius R of the surface to be
tested is smaller than 30mm
，
the small support ring or the shaped support rings should be chosen, see figure 2.
Figure 2
●
Support of test sample
Support is not necessary for heavy sample.
Medium-weight parts must be set on the smoothing and stable plane. The sample must set absolutely equability
and without any wobble.
●
The sample should have enough thickness, minimum thickness of sample should conform to table 3.
●
For the sample with hardened layer on surface, the depth of hardened layer should conform to table 3.
●
Coupling
