ASME B89.1.10M:2001 pdf free download

ASME B89.1.10M:2001 pdf free download.DIAL INDICATORS(FOR LINEAR MEASUREMENTS).
This Appendix is intended to provide general guidance and awareness regarding testing. operating. and enironmenial considerations of indicators. Any condi(ions that exceed the testing. operating. and environmen. tat rccommcndatmns and limitations of the instmmcrn should be investigated, for (he effect on (he accuracy and repeatabilily of (he indicator.
A2 PRECONDITION
A2.1 Soak Out
Allow the indicator to come to the same temperature as the test equipment. This can usually be achieved by mounting the indicator in the test fixture and then allowing it to Thoak out” for at least I hr before beginning the test procedure.
A2.2 Visual Inspection
The indicator should be checked for damaged or missing parts. Check the dial indicator for wear points on the gaging tip ball and ensure that no flat places are worn on the hail. Ensure that the mechanical action of the gaging mechanism moves smoothly. with no evidence of sticking or binding, and makes no abnormal sounds when it is extended and retracted several times through its full range. Verify that there is no interference among the hands, dial face, and crystal and that the comact mt is on tight. Ensure that the lever style indicator has ihe correct contact tip length, as specilied by the manufacturer.
A3 TESTING AND OPERATING CONSIDERATIONS
A3.1 Mounting and Fixturing the Indicator
Thc most mmoo cause for inaccurate readings is unstable or imsy mounting and fixiuring equipment. as well as incorrect contact tip length. The manner and type of equipment used to mount or fixture the indicator will alTcct the readings. The indicator should be mourned as in as stable a configuration as possible. to ensure accurate readings.
A3.2 Direction of Movement
When readings or measurements are recorded front opposite directions of the contact rnoement, the readings will include the hysteresis of the indicator. More accurate readings can be obtained by approaching the surface to be measured from the same direction of contact movement.
A3.3 Alignment Error: Type C Indicators
Type C indicators typically allow the contact to be adjusted. for access to work surfaces. When the contact is adjusted to an angle other than the angle recommended by the manufacturer, the reading should be corrected to compensate for the cosine error introduced.
A4 ENVIRONMENTAL CONSIDERATIONS
A4.1 Temperature
The temperature of the indicator, tixture. and environment can effect the accuracy and repeatability of readings. Most indicators and fixtures are made of different materials, and the materials have different coefficients of expansion. When measurements are made, the temperature should be kept as near to the reference temperature of 68’F (20°C) to minimize the differences in expansion. When indicators are used, especially in production shops, working temperatures are seldom at the reference temperature.