Performance Check
22 Dimple Grinder User’s Guide
To remove specimen
1. Remove the specimen mount from the Magnetic Turntable.
2. Place the specimen mount on a hot plate set at 130 °C.
3. Allow the wax to completely melt, then slide the specimen off the mount
with a cocktail stick.
4. Remove the mounting wax from the specimen.
Immerse in several acetone washes till the specimen is thoroughly clean.
Note: The use of an ultrasonic cleaner is not recommended since it may damage
some specimens.
4.11 Taper Sections
Dimpled specimens are ideal for analysis of surface segregation, platings, coat-
ings, etc. Dimple depth into the specimen is represented by the following equa-
tion:
Depth = x (2r - x)/2R
where:
R = wheel diameter,
r = dimple radius,
x = distance from the edge of the dimple.
This approximation always gives a value slightly less than the correct value,
with a maximum error of less than 10%. The correct value is given by:
Depth = {R
2
-(r-x)
2
}
1/2
- {R
2
-r
2
}
1/2
5.0 Performance Check
A complete check of the performance of the Dimple Grinder comprises, in addi-
tion to the Dial Indicator zero check (see Section 4.1), the following operations:
• Checking arm pivot friction.
• Zeroing Counterweight scale.
• Adjusting eccentricity (run-out).
• Checking vertical movement of specimen turntable.
• Aligning grinding wheel and stereo microscope.
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