Rockwell hardness values are expressed as a combination of a hardness number and a scale symbol representing the indenter and the minor and major loads. The hardness number is expressed by the symbol HR and the scale designation. UNITEDTEST hardness testers are based on the same construction principle of the COMP series which are already well known for their economic, reliability and easy using.

Principle:

1. The indenter moves down into position on the part surface
2. A minor load is applied and a zero reference position is established
3. The major load is applied for a specified time period (dwell time) beyond zero
4. The major load is released leaving the minor load applied

The resulting Rockwell number represents the difference in depth from the zero reference position as a result of the application of the major load.

Model:
HRS-150 LCD Display Rockwell Hardness Tester
HRMS-45 LCD Display Superficial Rockwell Hardness Tester

1),advanced testing technique and high quality LCD displaying, except the test table moving up and down, all others realized automatic action, then avoids the operation and readout error;
2), Equipped with a built-in printer, hardness testing result can be output by printing.
3), The RS232 Hyper Terminal setting is for the Functional expansion by the user
4), Wide scale (HRA, HRB, HRC, HRD, HRE, HRF, HRG, HRH, HRK, HRN, HRT);
5), Exchange hardness values among hardness scales: (HRA, HRB, HRC, HV, HB);

Standard Rockwell hardness block
Diamond Rockwell hardness indenter,
∮1.5875mm ball indenter,  Testing table (big, medium, “V”),
Weight (a, b, c), 
Power cord,
Lever,

ASTM E18 “Standard Test Methods for Rockwell Hardness of Metallic Materials”

ISO 6508 “Metallic materials — Rockwell hardness test”

ASTM D785 “Standard Test Method for Rockwell Hardness of Plastics and Electrical Insulating Materials”