The SH-21A is very easy to use and requires no special knowledge of hardness testing in order to operate the instrument. The unit includes all four hardness scales and you can switch between them at the touch of a button.
Applications
Evaluation of carburizing, standard quenching and high-frequency quenching
Diamond indenter for Micro-Vickers (facing-to-surface angle of 136 deg)
Measuring load
Approx 1kgf (roughly 10N)
Approx 2kgf (roughly 20N)
(These loads indicate those in typical applications. As the specification varies according to the object to be measured, please contact us for details.)
Measuring range
Rockwell hardness: 10.0 HRC to 70.0 HRC
Vickers hardness: 100 HV to 999 HV
Shore hardness: 20.0 HS to 99.9 HS
Brinell hardness: 85 HBW to 550 HBW
AC adapter (100 to 240V) or lithium ion rechargeable battery
Minimum target size
15 mm (width) x 15 mm (length) x 7 mm (thickness)
Measurement Principle
The Ultrasonic hardness tester model SH-21A differs completely from traditional hardness testers. Instead of measuring the size of the indentation of the test sample using a microscope, it uses a diamond indenter equipped with a vibrating rod that presses on the test surface at a fixed load and then measures its hardness by applying ultrasonic vibrations and analyzing its damping effect. When the vibration rod is applied to a soft-surfaced test sample with identical qualities and at a fixed force, it makes a deep indentation and gets locked into the groove. Due to this, the resonance frequency increases. Conversely, it does not get locked in when used on hard test samples and the resonance frequency drops. The test sample's hardness can be calculated using the correlation between this deviation and the tested hardness.
