Hardness Testers

Tru-Blue II Hardness Tester

hardness testerSince 1984, United has manufactured computer-controlled closed loop Hardness testers. Our second generation Hardness tester, the Tru-Blue II is the lowest priced US manufactured closed loop tester that meets ASTM E18, ISO 6508 specifications and NIST recommendations.

The Tru-Blue II comes standard with a Direct certification of the hardware calibration with NIST traceability and a factory one-year indirect calibration for customer specified hardness testing scales. The tester can be put into operation without the need for an additional on-site calibration or manufacturers assistance!

Having no dead weights, pivot points and knife edges to move out of adjustment, the Tru-Blue II can be moved to a new location without having to be re-calibrated. When mounted on United's optional mobile stand, the Tru-Blue II is transportable to different locations.

Tru-Blue II Brochure

Tru-Blue II Hardness Tester Features:

    • 15 regular scales.
    • 15 superficial scales.
    • 5 preset load dwell times including plastics.
    • Computer controlled application of loads.(closed-loop)
    • Force measured via load cell
    • Display resolution: points, tenths and hundredths.
    • Serial, A Parallel for Dot Matrix printing & PS/2 Connections.
    • Statistics Scale: Avg, range, min/max, Std deviation and number of tests.
    • Vacuum fluorescent display.
    • Automatic cylindrical correction.
    • Scale to scale conversion.
    • Parts IN/OUT limit alert.
    • Bi-directional loading capability.
    • Parts clamping device.
    • Factory direct certification: Depth, load, hysteresis & timing.
    • Factory indirect certification: B, C, 30N & 30T. Additional scales available.
    • CE approved.
    • 2-year warranty.
    • Vertical capacities: 10, 14, 18 & 20 inches.Custom vertical heights available.
    • Throat depth: 5.5 in 120-240 VAC, 50/60 Hz. Single phase, 1 amp.

rockwell testerTru-Blue Universal Features


    • Same as Tru-Blue II


    • Test Forces in Kg.:2, 2.5, 4, 5, 6.25, 7.8125, 10, 15.625, 20, 30, 31.25, 40, 62.5, 100, 120, 125, 150, 187.5 and 250.
    • Test Dwell Settings selectable in 1 sec. increments: 5-30
    • Direct reading of one Brinell range.


    • Test Forces in Kg: 3, 5, 10, 30, 50, 100, and 120.
    • Test Dwell Settings selectable in 1 sec. increments: 5-30
    • Direct reading of one Vickers range.

NIST - Recommended Guide to Rockwell Hardness Testing

Practice Guide Rockwell TestersPublished by the National Institute of Standards and Technology, the Recommended Practice Guide, Rockwell Hardness Measurement of Metallic Materials, is essential reading for anyone concerned with hardness testing.

Written by Samuel R. Low of the National Institute of Standards and Technology, this book contains detailed information on everything related to Rockwell Hardness testing, from test procedures to references for test block standards to direct and indirect verifications. This publication resolves several questions including the following:

    • How often should indirect verification be performed? (Page 54)
    • Should my hardness tester be "Directly Verified"? (Page 44)
    • Should machine hysteresis be checked? (Page 45)
    • How does the test cycle time affect hardness readings? (Page 27)
    • What about force verification? (Page 45)
    • What happens if the machine forces are adjusted? (Page 45)

Download the complete on-line version of this publication (requires Adobe Acrobat Reader). To order the print version, please contact United Calibration Corporation at (714) 638-2322 or FAX (714) 897-8496. We will be glad to mail you a copy free of charge.

United offers a full line of hardness accessories

    • Hardness TesterRockwell, Brinell and Micro hardness test blocks: All test blocks come with a certification sheet containing all the necessary calibration information.
    • Rockwell diamond indenters: Scales A, C and N. All diamond indenters come with certifications.
    • Heavy load Vickers and Micro hardness diamond indenters: ¼ , 7mm and 8mm shank sizes and Tukon.
    • Carbide ball indenters: 1/16, 1/8, ¼ and ½ inch. 2.5, 5 and 10mm.
    • Anvils and support devices: Spots, flats, "V", Vari and Jack rests.
    • Additional accessories: 2 inch roll mini serial and parallel printers, stationary and mobile stands, foot switch to activate test cycle, mini PS/2 keyboard.

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United Tru-Blue II Hardness Tester: Choice of the Very Best!

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