The Esatest principle, developed by Ernst, is an innovative approach to hardness testing that leverages the correlation between penetration depth and changes in residual electrical resistance. This technology employs a special indenter, enriched with boron to make it electrically conductive, that provides measurements based on electrical resistance changes induced by varying loads. This indirect method offers several advantages, such as enabling measurements with very low loads to minimize damage to finished parts and allowing tests in positions that conventional instruments cannot reach.

Key features of Esatest technology include:

• Measurement Capability: The system can measure across a range of loads, including very low ones, and display results in multiple hardness scales (Brinell, Vickers, Rockwell, and Super Rockwell).
• Calibration and Measurement: The calibration curve is obtained using a test block of known hardness to establish the relationship between load and resistance. The measuring curve, captured during testing, allows for comparisons between measured hardness values based on this relationship.
• Technology: By leveraging the conductive properties of a boron-doped diamond indenter, Esatest technology utilizes the correlation between penetration and residual electrical resistance. The plasma-based chemical deposition method is used to create the boron-enriched diamond indenter, which enhances the electrical resistance measurements.

This technology is employed in two main instruments:

1. E-Handy: A portable instrument designed for on-site testing, allowing measurements in areas otherwise inaccessible without dissecting the workpiece. It features immediate data exchange capabilities with a tablet for convenience.

2. MTR: Designed for laboratory use, it is capable of reaching specific points and downloading data directly to a computer.

The Esatest method's unique capability to perform hardness tests in various challenging conditions, using low loads and electrical resistance measurement, positions it as a versatile and efficient solution in the field of material hardness testing.