Quick Guide to Precision Measuring Instruments
Mu-checker
Probe A sensor that converts movement of a contact point, on a stylus or plunger, into an electrical signal. Lever probes Lever probes are available in two types. The most common type uses a pivoted stylus so the contact point moves in a circular arc; this type is subject to cosine effect and, therefore, measurements may require linearity correction if the direction of measurement is much different to the direction of movement of the contact point. The less common type uses a parallel translation leaf-spring mechanism so contact point movement is linear; this type requires no correction.
Comparative measurement A measurement method where a workpiece dimension is found by measuring the difference in size between the workpiece and a master gage that represents the nominal dimension. This method is usually applied when the measurement to be made is greater than the measuring range of the instrument. Linearity The ratio of proportionality between measuring system output and measured distance. If this is not constant within acceptable limits then correction is required.
0 (zero) point A reference point on the master gage in a comparative measurement.
Pivoted stylus type 519-521 (measuring direction can be switched with the up/down lever) 519-522 (measuring direction is not switchable)
Sensitivity The ratio of the electric micrometer output signal to the input signal to the amplifier. The sensitivity is normal if a value as expected from the given displacement is displayed. Tolerance setting Tolerance limits can be set on the electronic micrometer to provide an automatic judgment as to whether a measured value falls within the tolerance. Lever-head angle Before measurement, be sure to confirm that probe sensitivity adjustment has been completed. Changing the probe angle will cause variation in the measured values. Adjust the probe angle to obtain an optimum sensitivity before starting measurement. If it is difficult, adjust the sensitivity with the probe angle set to 0°, and after measurement, correct the measured values according to the actual probe angle (by multiplying the measured value by a correction factor). Tips Correction using a correction factor may result in lower accuracy than when adjusting sensitivity with the actual probe angle.
Parallel translation type 519-326 (measuring direction can be switched with the upper dial)
Pre-travel The distance from first contact with a workpiece until the measurement indicator reads zero.
G
0
0
First contact.
Plunger moves until the indicator reads zero.
測定子が フリーの状態
測定子を メータが 0 になるまで 押込んだ状態 ゼロ
+90°
Measuring force The force applied to the workpiece by the probe when the indicator registers zero. It is indicated in newtons (N). Digimatic code A communication protocol for connecting the output of measuring tools with various Mitutoyo data processing units. This allows output connection to a Digimatic Mini Processor DP-1VA LOGGER for performing various statistical calculations and creating histograms, etc.
0°
Bottom surface of the probe
-90°
Angle: θ
Workpiece surface
Distance from the workpiece surface: L*
Angle: θ
Correction factor
―
0°
1.00
10° 20° 30° 40° 50° 60°
Approx. 3.1 mm Approx. 8.8 mm Approx. 13.9 mm Approx. 18.3 mm Approx. 21.6 mm Approx. 23.8 mm
Approx. 0.98 Approx. 0.94 Approx. 0.87 Approx. 0.77 Approx. 0.64
Open-collector output A direct connection to the collector of a driving transistor.
Approx. 0.50 * Value when using a carbide probe with spherical diameter of ø2 that is installed before shipment. When using a ø1 (or ø3) carbide probe, subtract (or add) 1/2 of the difference in spherical diameter.
G-25
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