Microhardness Testing

Applications of the HM 2000 microhardness tester 

The Fischer HM 2000 micro hardness tester is a very versatile hardness testing device with applications for paint and electroplated coatings, hard material DLC (Diamond Like Carbon), PVD and CVD coatings, surgical implants, synthetics and rubber hardness and material analysis.

Further important applications of this micro-hardness test method can be found in quality control of hard material coatings on cutting and forming tools, on galvanic coatings such as deposited nickel coatings, of gold coatings on contacts for electrical components, of paint and lacquer coatings in the automotive industry, synthetic foils and many more.

New benefit of the HM2000 microhardness tester

The HM 2000 micro hardness tester now has a maximium load of 2000mN, which helps greatly with hardness tests or measurements on rough surfaces.  The HM 2000 hardness tester also has a load resolution of 0.04mN and the hardness tester's automatic surface sensor eliminates many operator errors.

Above all, the HM 2000 hardness tester uses the load/indentation depth method, which measures the force applied and indentation depth continuously. The microhardness tester also measures the force as the indentor is removed, providing information on the elastic and plastic properties of the material.

Schematic representation of the HM2000 microhardness measuring cycle

Key to Microhardness Measuring Cycle

t0 - t1
Load applied from min. to max. level. Both plastic and elastic deformations contribute to hardness indentation. The hardness calculation is made only in this time interval
t1 - t2
Max. load held (at predefined level and time). Indentation depth change indicates creep properties
t2.- t3
Load gradually reduced “modulus of indentation” determined from curve slope at Fmax
t3 – t4
Minium load held constant giving information about, for example, paint damage(reflow behavior)

Understanding the HM hardness measurement principle

Hardness and other important material characteristics of thin coatings, either galvanically deposited or generated through a hardening process, are determined using the microhardness method according to DIN EN ISO 14577-1. The HM 2000 microhardness testing system utilises this load/indentation depth method, otherwise called “Martens Hardness HM” to differentiate it from the conventional hardness value determined according to Vickers.

With this method, the indenter – typically a Vickers or Berkovich pyramid – is continuously pressed into the material tested with an increasing test load, and then unloaded. The indentation depth of the pyramid is measured continuously during this penetration process. The hardness value HM is calculated from the selected maximum test load and the resultant indentation depth.

Benefits of the HM hardness measurement method

In addition to eliminating user variability during hardness determination, an important advantage lies in evaluating even very small indentations, because it is not necessary to measure the indentation visually. This makes it of paramount importance and value to applications with rough surfaces or coarse texture of the material or of the coating, where such a small dimension of the pyramid displacement would typically have led to unacceptable deviations of the measurement.

With a maximium load now at 2000mN, the measurements on harder coatings are much improved as the indentations are increased and therefore uncertainty of measurement reduced.

Reliable and reproducible test results ensure automated test runs. All this becomes possible with the Fischer HM2000 series of micro-hardness test instruments and in addition, the previously common universal hardness can also be computed from the recorded measurement plot.