Hardness Testing

Introduction

The hardness test is a mechanical test for material properties which are used in engineering design, analysis of structures, and materials development. The principal purpose of the hardness test is to determine the suitability of a material for a given application, or the particular treatment to which the material has been subjected. The ease with which the hardness test can be made has made it the most common method of inspection for metals and alloys.

Hardness is defined as the resistance of a material to permanent deformation such as indentation, wear, abrasion, scratch. Principally, the importance of hardness testing has to do with the relationship between hardness and other properties of material. The hardness test is preferred because it is simple, easy, and relatively non-destructive.

Application

Ultrasonic Hardness Tester is widely used to measure hardness of flange edges and gear root of stamping parts, molds, sheets, hardening surface of the tooth and gear and taper part hardness, hardness of the shaft, pipe including inside and outside wall, container, wheel, turbine rotor, bit blade, HAZ weld, printing roller, injection molding machine screw parts etc.

There are many hardness tests currently in use. The necessity for all these different hardness tests is due to the need for categorizing the great range of hardness from soft rubber to hard ceramics

The UCI principle determines hardness by measuring the frequency of an oscillating rod. The rod consists of a metal shaft with vibrating element and a pyramid-shaped diamond mounted on one end.

The brand-new Krautkramer MIC 20 combines the two most successfully applied portable hardness testing principles in one instrument. Whether you want to use the UCI principle or the dynamic Rebound testing method – the MIC 20 offers both possibilities. All you need is just one instrument and all current UCI probes and impact devices can be plugged in and used.

To perform a measurement, the diamond is forced into the material by spring pressure. And the device measures the frequency and compares it to the frequency in air. The frequency is lower for hard materials and becomes higher as the indentation increases in size. The instrument converts the frequency shift to hardness value.

Benefits

The main advantages of the UCI method are possibility to testing hardness of:

• small parts;
• thin-walled products;
• products with difficult access to the testing area;
• surface hardened layer.

PRETECT offers the hardness testers with UCI probe: