Machinery's Handbook, 31st Edition
798 CALIBRATION OF INSIDE MICROMETERS Tubular Type Inside Micrometer.— A description of the calibration and equipment re- quirements for the tubular type inside micrometer are given in Table 18. Table 18. Calibration Requirements of Tubular Type Inside Micrometer Calibration Description Test Instrument (TI) Characteristics Performance Specifications Test Method
Range: All Accuracy: As listed in Tables 4, 5, and 6 Range: All Accuracy: ± 0.00025 in Range: All Accuracy: As listed in Tables 4, 5, and 6
Measured using a standard measuring machine or supermicrometer referenced to gage blocks
Length
End caps
Extension Rods
Equipment Requirements
Minimum Use Specifications
Calibration Equipment
Alternate Selection
Description
L.S. Starrett Co. SC 36.A1 SC 36.MA1X L.S. Starrett Co. SS8.A1X Pratt & Whitney Model PC-250
L.S. Starrett Co. SC 88.A1X SC 88.MA1X
Range: 0.05 to 4 in Accuracy: ± 12 m in from stated value Range: 5 to 20 in Accuracy: ± 5 m in/in Range: 0 to 10.00 inch 0 to 250 mm Accuracy: 20 m in Range: 0 to 148 inch 0 to 1200 mm Accuracy: 50 m in
Gage Block Set
Gage Block Set
Supermicrometer
Standard Measuring Machine Pratt & Whitney Model DMM-1219 Preliminary Operations.— 1) UUT shall be brought into the calibration area at least 4 hours prior to beginning the calibration process. 2) Ensure that all working surfaces are clean and free from dust and dirt. 3) The UUT must be free from all rust, nicks and burrs that would affect the results of the measurements and operation of the UUT. 4) Linear measurements are affected by temperature and all measurements must be con ducted in a temperature controlled environment. The preferred environment is 68°F with no greater than ±1° per hour deviation from nominal. The temperature must have been stable and within the preferred range for a minimum of 8 hours prior to beginning the calibration soak time. Length Calibration Process.— Preferred Method: 1) Install the shortest extension rod available for the UUT set being calibrated. If the UUT has end caps (Type II Class 3 Style A) install just the end caps. This section will calibrate the micrometer head accuracy. Note: If the TI being calibrated is equipped with two end caps that can be removed and interchanged (Type II Class 3 Style A), the end caps must be checked for wear and must be the same length (nominal 0.250 inch). If the end caps differ in length by more than ±0.00025 inch (as measured on the Supermicrometer or Standard Measuring Machine , both TI end caps must be replaced. 2) Select a gage block of a length close to the nominal length of the UUT when set to zero on the micrometer head and the extension rod or end cap for minimum length indication is installed.
Copyright 2020, Industrial Press, Inc.
ebooks.industrialpress.com
Made with FlippingBook - Share PDF online