Rockwell hardness scale based on indentation hardness of a material with a 120° diamond spheroconical under 150 kgf
A Rockwell hardness tester
The Rockwell hardness test is a hardness test based on indentation hardness of a material. The Rockwell test measures the depth of penetration of an indenter under a large load (major load) compared to the penetration made by a preload (minor load). There are different scales, denoted by a single letter, that use different loads or indenters. The result is a dimensionless number noted as HRA, HRB, HRC, etc., where the last letter is the respective Rockwell scale. Larger numbers correspond to harder materials.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).