Modeling transient adhesive wear of tungsten carbide inserts tested with an angular setting

Abstract

The standard transient adhesive wear equation had been used for modeling pins tested with a full contact with a counter disc. The wear volume against distance curve (wear curve) obtained from such a test can be divided into two regimes: the curvilinear transient regime and the linear steady-state wear regime. The slope of the wear curve at the beginning is a lot higher, and it gradually decreases with sliding distance towards the steady-state wear regime. On the other hand, for inserts tested with an angular setting, generally, the wear curve is in the form of a straight line with a constant slope. This is due to the limited volume of asperities available for wear initially, but as wear progresses, the volume of asperities available will also increase. Generally, the volume loss of inserts with an initial angular setting with the counter disc is lower, as compared with those obtained with a full contact setting. The wear volume also increases with load, speed and temperature. As the wearing conditions for both cases are different, a new exponential transient adhesive wear equation has, therefore, been developed to model the transient wear volumes of tungsten carbide inserts tested with an angular setting. Excellent results with an average correlation coefficient of 0.9964 and an average deviation of about 10% are obtained. Inferior results are obtained when the standard transient adhesive wear equation is used for modeling the inserts with an angular setting, as the assumption made in its derivation is no longer applicable. The modeling results obtained from using both equations, as well as some evidence obtained from SEM and optical examinations of the worn inserts and wear tracks will be discussed in details in this paper. The experimental wear data used to support this modeling work are obtained earlier from a high temperature wear testing rig, in which Sandvik tungsten carbide inserts are tested with an angular setting with a hot work tool steel counter disc. The experimental parameters used are: (i) Applied loads of 40 and 50 kgf, (ii) speeds of 100 and 130 m/min, (iii) temperatures of 25, 200, 400 and 600 °C, and (iv) distances from 1000 m to 16,000 m.