Portable Hardness Testers, as the name suggests, are portable (moveable) instruments that are used for on-site hardness measurement tests. The advantage of portable hardness testers over conventional stationary testers is that while the latter require the sample to be brought to the testing apparatus, the portable testers can be taken to the site for the hardness test. This facilitates hardness testing of materials and even that of finished products. (In the latter case, it is mostly a quality-test).



Working Principle Of Portable Hardness Testers

Portable Hardness Testers are based on two different principles.

The first method, known as the UCI or Ultrasonic Contact Impedance method, measures the frequency shift of a resonating rod with a Vickers-diamond tip. The resonating or reverberating effect is brought about by causing the diamond to penetrate into the test material through application of a specific test weight. The frequency shift is then assessed and converted electronically to give the hardness value.

The other working principle is the rebound method. During the process, an object is forced or driven onto the surface of the sampling material. The velocities the body attains immediately before and after its collision with the test material are recorded. The ratio between these two velocities gives the hardness measure/rating of the material. The conversion tables stored in the instrument convert the hardness into different scales.

Portable Hardness Testers And Their Uses

Portable Hardness Testers that are based on UCI method are essentially user-friendly. These instruments usually include all the four hardness scales - Brinell, Rockwell, Shore and Vickers. You can simply select one at the mere touch of a button. When the diamond-tipped rod is held against the material surface for a few seconds, the hardness measure is immediately displayed on the selected scale. Different measurements are taken and the average is calculated by the machine on its own.

UCI-based hardness testers are ideal for measuring the hardness of large-scale structures such as aviation aircrafts, bridges, ships, etc. as part of quality checking and maintenance.

Leebs' Rebound Principle based portable hardness testers too give accurate hardness measures. These are perfect for testing large, heavy items and machinery parts, no wonder that these instruments are used widely for quality-control tests.

Some portable hardness testers like the Krautkramer MIC 200 combine both the hardness testing principles and these devices can be used for UCI probes and rebound tests.

The latest in the range of portable hardness testers are the digital testers. These testers provided with the USB interface allow data transfer to your PC or printer, thereby minimizing measuring errors.

Barcol Hardness Testers, another type of hardness testers are used to measure hardness of plastics and soft metals - that of raw materials and/or field-testing of final products.