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The GAR Precision Reference Standard provides an
economical calibration tool which permits the technician to calibrate
surface analyzing equipment to its peak efficiency. It is the only
calibration block on the market to show the actual patch mean values of
low and high microinch surfaces and certified by the National Institute
of Standards and Technology. (N.I.S.T.).
The surface of the Precision Reference Standard
consists of a series of parallel, uniform, "V-shaped" grooves having an
included angle of 150° between the sides. Since the surface character of
the Precision Reference Standard is unlike normally machined surfaces, it
is not recommended for use in visual and tactual comparison. |
Method of Calibration
used as reported by N.I.S.T.
The patch mean values identified on the border of
the standard is the roughness average (Ra) obtained from five measurements
taken in the areas defined in the sketch shown. The sketch applies to
both patches by simply rotating the standard 180°. These values represent
the average surface roughness of each trace using 0.0004" (0.010mm) radius
diamond stylus and a 0.030" (0.8mm) roughness width cutoff, in accordance
to the American National Standards Institute (ANSI) specification titled:
"Surface Texture, Surface Roughness, Waviness and Lay". ANSI/ASME
B46.1
The Specimen under test was calibrated by a
one-step transfer from the appropriate master using a stylus type
instrument. Five measurements were made over each of five areas
distributed over the whole specimen. |
Reports of
Calibration by U.S. Department of Commerce, National Institute of
Standards and Technology
The property of surface roughness in the 125 microinch range
and below is maintained by N.I.S.T. by means of master roughness specimens
conforming to ANSI B46.1. The master specimens were calibrated by
measuring their surface profile with a stylus instrument which in turn was
calibrated by a interferometrically measured step. The areas under the
profile curves were then measured and the roughness average computed. The
accuracy of this measurement is 2% for the 119.5 and 1 microinch for the
16.1. |
Electroforming
