18
and instrument stay in the same ambient to make them with the same temperature.
Temperature shall be not variable considerably during measurement. If temperature
deviating 20
and workpiece/instrument with different temperature, this will result in
error of measurement.
If above mentioned condition can’t be met, the error in length will be:
L
[
w
(t
w
20)
i
(t
i
20)]
L
Where:
w
i
: linear expansion coefficients for workpiece and instrument scale;
t
w
t
i
: actual temperature for workpiece, actual temperature for instrument
L, L
: normal length of workpiece, error in measurement due to different
temperature
Linear expansion coefficient for scale: 10
10
-6
1/
During measuring large-size high precision workpiece, we shall check temperature of the
workpiece and instrument and find out the linear expansion coefficient for workpiece.
Then calculate L according to the above formula and correct the measuring results. the
workpiece and instrument temperature can be checked with a attached thermometer. With
regard to our EX-100 instrument, the error in measurement will be corrected by the
software.
5.2 Measuring a typical workpiece
5.2.1 Measurement of workpiece outer dimensions
For workpiece outer dimensions, there are two measuring methods (absolute and
relative).
First adjust the cap-shaped measuring accessories, the measuring force according to
5.1
and take attention for temperature. Then select and mount a appreciate worktable, and fix
the workpiece on the worktable.
Procedures for absolute measurement:
a) First make the two cap-shaped measuring accessories contact, record the reading
Lo and reset the display by pressing a key;
b).Move the workpiece between the two cap-shaped measuring accessories and make
them contact to find the “turn-over pint” and record the reading L
1;
c).Workpiece actual
dimension L =L
1
L
0
Summary of Contents for EX-100
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