To understand the wear resistance of hardmetals we have to know that all surfaces of industrial components have a certain degree of roughness. In tribological terms, this is an important initial feature which actually means that when two surfaces slide against each other, they come into contact in line with the small parts of the apparent area of contact, causing loss of material on both sides. It can thus be said that the mechanical nature of the contact is usually determined by surface protuberances, commonly called roughness.
The following types of wear are defined:
The nature of wear is a very complex matter and depends on many variables. For comparative purposes, it is nonetheless possible to carry out laboratory measurements by evaluating the samples under specific conditions.
Generally, for the evaluation of wear resistence of hardmetal samples, reference is made to ASTM B611-13. The sample is pressed against a rotating steel disc immersed in an abrasive mud and with constant load. The resulting loss of volume in the sample is thus measured.
Schematic representation of the testing machine
Detail of the worn area with the machine running
For each degree of hardmetal produced by Nashira Hardmetals, we have produced samples to ASTM B611-13 standards. Each suitably-prepared sample was tested for 10 minutes before assessing the loss of volume.
A sample after the wear test
The data obtained was adapted to the following graph:
To choose the right degree of hardmetal, the expected life of the tool must be taken into careful consideration. Nashira Hardmetals can support you in the choice of hardmetal by providing the proper indications to engineers and designers.
Further details
[1] Wear Control Handbook, Edited by M.B. Peterson and W. O. Winer, ed.ASME, 1980.
[2] J. K. Lankaster, in Friction and wear of composite materials, ed. Fredrich K., Elsevier
[3] Measurement Good Practice Guide No.20 Mechanical Tests for Hardmetals B Roebuck, M Gee, E G Bennett & R Morrell Centre for Materials Measurement and Technology National Physical Laboratory