Precision testing of scratch, shear and surface damage resistance
The Taber 550/551 Shear & Scratch Tester is a precision instrument designed to evaluate the resistance of flat, rigid materials to scratching, shearing, gouging, marring, scraping and engraving. Using interchangeable test tools and controlled loads, it provides a versatile method for evaluating surface durability and comparing the performance of materials, finishes and protective coatings.
Controlled and repeatable surface testing
A motorized turntable rotates the specimen beneath the selected scratch or shear tool at a constant speed. The calibrated sliding weight on the scale beam allows the applied load to be adjusted from 0 to 500 g, while an additional weight extends the standard testing range to 1000 g. Graduations on the beam are marked in 10 g increments. Optional weights can extend the range down to 0–50 g for scratch-sensitive materials or up to 1500 g for higher-load testing.
Interchangeable tools for different materials
A variety of diamond, carbide and contour shear tools are available to adapt the instrument to different test materials and procedures. This allows the same system to investigate scratch resistance as well as shear damage and other forms of localized surface failure.
Evaluate coatings and material uniformity
In addition to measuring scratch and shear resistance, the tester can be used to investigate the adhesive qualities of protective coatings, compare the relative homogeneity of materials and study changes caused by ageing under controlled conditions. Typical test materials include paints, powder coatings, plastics, laminates, anodized materials, soft metals, glass and other rigid surfaces.
Adjustable for different specimen thicknesses
The scale beam is mounted on an adjustable gauge block that accommodates specimens up to 12.7 mm (0.5 in) thick. The height adjustment keeps the beam level relative to the specimen and turntable, helping maintain consistent test geometry.
Model 550 and Model 551
The Taber 550 operates on 115 V, 60 Hz power with a turntable speed of 0.6 rpm and includes S-20 and 139-55 cutting tools. The Taber 551 operates on 230 V, 50 Hz power at 5 rpm and includes S-20 and 139-56 tools. The Model 551 is designed to meet ISO, DIN, EN and other European test standards where applicable.
Practical evaluation of test results
Scratch resistance can be determined by identifying the minimum load required for the test tool to penetrate the material surface, or by comparing scratch width at a specified load. For shear testing, results can be based on the minimum load required to shear the surface. A 10× measuring magnifier is supplied with the tester to assist with visual evaluation of the resulting scratch or groove.
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