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:
HR-150DT Motorized Rockwell Hardness Tester
HRM-45DT Motorized Superficial Rockwell Hardness Tester

1), High measuring accuracy, reliable performance and wide applicable fields;
2), By adopting the motor driven automatic loading and unloading technique, this thoroughly eliminates human error in the operations.

HRB, HRC standard hardness blocks,
Diamond Rockwell hardness indenter,
∮1.5875mm ball indenter
Testing table (big, medium, “V”),
Power cord

∮3.175mm, ∮6.35mm, ∮12.7mm Steel Ball Indenter (optional)

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”