HR Series Hardness Testers

December 12, 2011

HR-200/300/400/500 series Rockwell hardness testing machines from Mitutoyo America Corp. reportedly offer enhanced performance with improved frames, better ergonomics and other productivity boosting features. The HR series hardness testers share a new frame design that provides maximum clearance for flexible workpiece positioning and to facilitate mounting on any flat surface. The testers feature a projected-nose indenter arm for easy access to interior and exterior surface. All HR series hardness testers are robust and suitable for production floor and lab settings, according to the company.

Even the entry-level HR-210MR Rockwell tester is feature-packed. It has a motorized major loading system to reduce the chance for operator error (common with conventional oil dash pot systems). The result is improved accuracy and repeatability. In addition, the HR210MR has a dial indicator readout with a preset function that automatically zero-sets the primary (minor) test force.

Related Glossary Terms

  • Rockwell hardness number ( HR)

    Rockwell hardness number ( HR)

    Number derived from the net increase in the depth of impression as the load on the indenter is increased from a fixed minor load to a major load and then returned to the minor load. The Rockwell hardness number is always quoted with a scale symbol representing the indenter, load and dial used. Rockwell A scale is used in connection with carbide cutting tools. Rockwell B and C scales are used in connection with workpiece materials.

  • clearance


    Space provided behind a tool’s land or relief to prevent rubbing and subsequent premature deterioration of the tool. See land; relief.

  • flat ( screw flat)

    flat ( screw flat)

    Flat surface machined into the shank of a cutting tool for enhanced holding of the tool.

  • hardness


    Hardness is a measure of the resistance of a material to surface indentation or abrasion. There is no absolute scale for hardness. In order to express hardness quantitatively, each type of test has its own scale, which defines hardness. Indentation hardness obtained through static methods is measured by Brinell, Rockwell, Vickers and Knoop tests. Hardness without indentation is measured by a dynamic method, known as the Scleroscope test.