"Ultrasonic Contact Impedance" is based on a 136 degree diamond at the end of a vibrating rod being depressed into the test surface at a fixed load. The difference in ultrasonic vibration frequency is then calculated into a hardness value. The UCI test procedure is slower than the Dynamic Impact style, however, the “UCI” method of hardness testing is portable, easy, and accurate. It also has its advantages when utilized for certain testing applications. UCI testers are not restricted to large mass items like dynamic type testers. These units can test metals as thin as 1mm and at a hardness value as low as 20HRC (75HB). They also excel at performing hardness tests on larger, harder metals as well. Another reason for the rise in popularity is that the UCI method is categorized as “Non-Destructive”. That translates into less scrap parts/lower mfg costs due to necessary inspections.
“Dynamic Impact” is based on the Leeb principle of hardness, developed by Dietmar Leeb in the 1970s. A spring-loaded impact body is thrust to the test surface, affecting rebound. The speed of both the initial thrust and the rebound is measured in a non-contact mode. This is calculated as a Leeb hardness value and then automatically converted to Rockwell C, B, Brinell, Vickers, and Shore Values. It has effectually brought easy, fast, and accurate results to portable hardness testing.
