Portable Hardness Testers

What Portable Hardness Testing Measures

Portable testers measure hardness on the part instead of bringing the part to a bench machine. A rebound (Leeb) instrument fires an impact body at the surface and compares its rebound velocity with its impact velocity, and the result converts into Rockwell, Vickers, Knoop, Brinell and Shore terms. An ultrasonic contact impedance (UCI) probe presses a Vickers diamond into the surface and reads hardness from the shift in the resonant frequency of a vibrating rod. A portable Brinell kit drives a ball into a calibrated test bar and into the part with one hammer blow and compares the two impressions. All three give a local surface reading, which describes the spot that was tested and not the whole part.

Standards for Portable Hardness Testing

Leeb testing follows ISO 16859 and ASTM A956, which cover the method, the verification of instruments and the calibration of test blocks for steel, cast steel and cast iron. The UCI method is covered by ASTM A1038, a practice for comparative hardness values on the part itself. Brinell testing, including portable machines that meet the verification requirements, falls under ASTM E10 and ISO 6506. A result is most useful when the report names the method, the scale and the edition of the standard.

What Affects Portable Hardness Results

Surface preparation matters first, because scale, coatings and contamination change the reading. Part mass and wall thickness then decide the method: rebound testing suits heavy sections, while UCI works on thin-walled structures with a wall thickness over 1 mm. The impact direction, the impact device and the material all influence a Leeb value, and a conversion to another scale is valid only inside the range established for that material. On a Telebrineller, accuracy depends on how close the test bar is to the specimen, within 15 percent of its hardness and of the same general material. Each method has a reference to check against: a test block for Leeb and UCI, and a calibrated bar for the Telebrineller.

Portable Hardness Testers from NextGen

The NG-LeebGen 3000 is a cable-free rebound tester with 360 degree automatic angle adjustment, a universal D impact device as standard and five further impact devices for confined spaces and heavier or rougher metal. The UH200 is an ultrasonic contact impedance tester with a 5 kgf manual probe as standard and optional manual and motorized probes for thin layers and small parts. The Telebrineller is a comparative Brinell kit that weighs under ten pounds and needs no power. Certified test blocks and Telebrineller test bars come from the same supplier.