The uniform hardness of Standard Telebrineller Test Bars is guaranteed to be within plus or minus 2% of the BHN inscribed on the end of the bar. They are constructed from different carbon steel alloys and finished ground to a 9/16″ square.

Using a Brinell manual or automatic microscope, the diameters of the imprints are then measured and translated to BrinellHardness Numbers. Automated microscopes, like the GenScope, are calibrated, computerized devices whose accuracy can be traced back to the National Institute of Standards. As a result, the Brinell Hardness Numbers are rounded to the nearest standard BHN found in Table I of ASTM Standard E10 at intervals of.05mm, and this BHN is engraved onto the end of the bar.

Please be aware that the relative hardness of the test bar and the test piece affects the accuracy of any test performed with the Telebrineller. When the Telebrineller is used appropriately, accuracy of 5% is consistently achievable, provided that the difference between the test piece’s and test bar’s BHNs is not greater than 15%.

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