Choosing a Hardness Tester - Rockwell, Vickers or Leeb?

Rockwell, Vickers or Leeb - what does each measure?

All three methods determine hardness, the resistance of a material to penetration by a harder body, but in fundamentally different ways. Rockwell (ISO 6508) measures the permanent indentation depth of a diamond cone or ball and gives a direct number. Vickers (ISO 6507) presses in a diamond pyramid and calculates hardness from the optically measured indent diagonal. Leeb (ISO 16859) is a dynamic rebound method used in portable instruments.

Rockwell is fast and easy to read and dominates in production and incoming inspection. Vickers is the most accurate method for small, thin or case-hardened surface layers, but it requires a polished surface and microscope evaluation. Leeb measures via the rebound velocity of an impact body and is the go-to method for large, heavy parts that do not fit in the lab.

Which method suits your material and part size?

The choice depends on hardness range, wall thickness, surface and part mass. Soft metals, thin sheet and case-hardened layers need a fine method with low load, while large forgings or welds can only be tested sensibly with a portable unit.

• Hardened steel and series inspection: Rockwell HRC is fast and robust.
• Case layers, sheet under 2 mm, small parts: Vickers or low-load HV.
• Grey cast iron and coarse grain: Brinell with a large ball averages the structure.
• Massive castings, shafts, welds on site: portable Leeb instrument.
• The part must rest firmly - support thin parts when using the Leeb method.

Portable or benchtop - when is each worth it?

Benchtop units deliver the highest reproducibility and are the standard for acceptance and series testing in a climate-controlled room. Portable instruments (Leeb or handheld UCI) go to the part when it is too large, too heavy or already installed.

The UCI method (Ultrasonic Contact Impedance) is a portable alternative to Leeb: a Vickers diamond oscillates with ultrasound and measures the frequency shift as it penetrates. UCI also handles thin-walled parts and hard-to-reach spots where Leeb fails because of the mass it requires.

What else matters when buying and operating?

A hardness tester is only as good as its calibration and surface preparation. Hardness reference blocks per ISO 6508‑3 / 6507‑3 belong to the basic kit and are used for a check before every test series.

• Plan reference blocks that match the method and hardness range.
• Polish the surface for Vickers, at least grind it smooth for Leeb.
• Account for the impact direction with Leeb or choose units with position compensation.
• Ask for a traceable ISO/DAkkS calibration certificate for acceptance testing.
• Check interchangeable indenters (diamond/ball) and matching test forces.

Frequently asked questions