Quick Guide to Precision Measuring Instruments
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PG29Quick Guide to MeasurementMaximum permissible errorMaximum permissible error (MPE) by measurement characteristics -- dial indicators with the bezel dia. 50mm or moreMaximum permissible error (MPE) by measurement characteristics --dial indicators with the bezel dia. 50mm or less and back plunger type dial indicatorsGraduation (mm)0.010.0050.0010.010.0050.0020.001Measuring range (mm)1 or lessOver 1 and up to 3Over 3 and up to 5Over 5 and up to 10Over 10 and up to 20Over 20 and up to 30Over 30 and up to 50Over 50 and up to 1005 or less1 or lessOver 1 and up to 2Over 2 and up to 51 or lessOver 1 and up to 3Over 3 and up to 5Over 5 and up to 105 or less1 or less1 or lessRetrace error33335789322344453.52.52Repeatability 3333455530.50.513333311Arbitrary 1/10 revolution 555581010125223.5888962.52.5Arbitrary 1/2 revolution88991012121793.5451111121294.54Arbitrary One revolution 8910101515152010456121214141054.5Entire measuring range810121525304050125710151618201265MPE for one revolution type dial indicators does not dene the indication error of arbitrary 1/2 and 1 revolution. * Values in the table above apply at 20ºC, which JIS B0680 denes as the standard temperature. * The measurement characteristics of a dial indicator have to meet both maximum permissible error (MPE) and measurement force permissible limits (MPL) at any position within the measuring range in any posture when the measurement characteristics are not specied by the manufacturer.ItemCalibration method Diagram of calibration setup in vertical posture (example)Tools for calibration (example)Indication errorHold the dial indicator with its spindle set vertically downward, retract the spindle (retraction direction) to set the dial hand at the zero point, and determine the indication error at the below-mentioned measurement points with reference to the dial graduations. - Every 1/10 revolution for the rst two revolutions- Every half revolution for the next ve revolutions- Every revolution for the next 25 revolutions - Every 5 revolutions for after the 25th revolutionFor one revolution type dial indicators and indicators whose graduations are not factors of 10, determine the indicatoin errors at the closest measurement points mentioned above. Next, retract the spindle more than three graduations over the entire measuring range, reverse the spindle displacement (extension direction), and determine the indication errors at the same points measured during spindle retraction. Then determine the indication errors and the retrace errors with reference to the bidirectional indication errors thus obrained. When automatically reading errors by automatic inspection machine, determine the gap between the dial hand and the graduation mark with reference to the displacement of the measuring instrument. For 0.01mm graduation dial indicators: A micrometer head or other measuring unit with 0.5μm graduation or less and instrumental error of ±1μm and a supporting stand. For dial indicators other than the above: A micrometer head or other measuring unit with 1μm graduation or less and ±1μm instrumental error and a supporting stand. Retrace errorRepeatabilityApply the contact point of the dial indicator perpendicularly to the upper face of a measuring stage, retract and extend the spindle quickly and slowly five times at a desired position within the measuring range and determine the maximum difference between the ve indications obtained. Measuring stageSupporting stand Measuring Force Holding a dial indicator, retract and extend the spindle continuously and gradually, and measure the measuring force at the zero, middle and end points in the measuring range. The largest value: maximum measurement force The smallest value: minimum measurement force The maximum difference in contact force measured when the spindle is retracting and extending at the same measuring position: difference in the measurement force Supporting stand Top pan type spring scale (graduation: 0.02N or less) or force gage (sensitivity: 0.02N or less) Supporting standDial indicatorMicrometer head or other length measuring unitSupporting standMeasuring stage Dial indicatorDial indicatorTop pan type spring scaleSupporting standIndication errorDial Indicator Standard B7503 : 2011 (Extract from JIS/Japanese Industrial Standards)

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