CALIBRATION OF OUTSIDE MICROMETERS Machinery's Handbook, 31st Edition
789
Calibration of Outside Micrometers Typical equipment requirements for calibration procedures are shown in Table 10; a description of the calibration is given in Table 11, and various types of monochromatic light sources are given in Table 12. Table 10. Calibration Equipment Standards Item Minimum Use Specifications Recommended Equipment Monochromatic Light Range: N/A Accuracy: N/A a Helium Discharge: 11.6 m in Length/Fringe Van Keuren L-1A or L-1
Range: Two optical parallels differing in thickness by 0.0125 in. Accuracy: 10 m in (flat and parallel)
Optical Parallel Set
Van Keuren: OP-2B
Range:
Starrett Webber SC 81.A1 Starrett Webber S2C 88. MA1X Starrett Webber SS 8.A1X Starrett Webber SS 8.MA1X
Gage Block Set
0.05 to 4 inch 2.0 to 450 mm 5 to 84 inch 125 to 500 mm
Range:
Gage Block Set
(Long Block Set)
Optional Equipment
b U6 Monochromatic Reflex Interference Viewer
a Helium Discharge:
Range: 6 in diameter Accuracy: N/A
11.6 m in Length/Fringe
Van Keuren V760300 a While the Helium Discharge Monochromatic Light is one of the most common frequencies in use, other monochromatic light sources are available (see Table 12) and all will produce the same results. The band count is multiplied by the fringe length value to obtain the flatness of the measured surface. See examples in the table Interpreting Optical Flat Fringe Patterns . b The U6 Monochromatic Reflex Interference Viewer is used to observe the base flatness of the depth micrometer directly through an optical flat. The same technique of fringe count can be utilized to obtain the flatness as is used for the OD micrometer anvil and spindle. Table 11. Calibration Description UUT Characteristics Performance Specifications Test Method
Range:
Measured with Optical Flat/Parallel converting fringe curvature to an equivalent linear value. For UUT with 0–1 inch (0–25 mm) range, measured at two positions with optical parallel set. Comparative measurement of UUT reading to gage block test setup to test the basic length and micrometer head linearity.
0 to 54 in. 0 to 300 mm Tolerance: See Fig. 12
Flatness
Range:
0 to 1 inch 0 to 25 mm
Parallelism
Tolerance: 50 m in.
0.0013 mm
Range:
0 to 54 inch 0 to 1400 mm Tolerance: See Table 21a and Table 21b
Length and Linearity
Copyright 2020, Industrial Press, Inc.
ebooks.industrialpress.com
Made with FlippingBook - Share PDF online