Experimental investigation of bearing wear of a gear unit DMGH 25.4 of horizontal cement mill

Abstract

Purpose Rotating machines play a strategic role in the process; it is the case of a gear unit of a cement mill. These machines are composed of tribo-pairs (bearings and gears, etc.) subjected to mechanical stress and harsh industrial environments. This study aims to make an experimental investigation of bearing wear of a gear unit DMGH 25.4 of a horizontal cement mill. Design/methodology/approach Several tests were carried out in collaboration with industrial Algerian companies, for example, spectroscopy, micro hardness, X-Ray diffraction analysis and microscopic examination of wear-characterized QJ1244 N2MA bearing. Findings Experimental results reveal that there are two types of bearing wear: the first is a continuous mode of damage. The second mode is the wear by a third body (wear debris in suspension in oil). The spalling results from the propagation of cracks through the thickness of the material generally give rise to cracks in the sub-layer depth hertz. An unusual hardening observed suggests that the damage was caused by the dissipation of a large surge of frictional energy lasting several milliseconds. It is found also that heating due to insufficient lubrication of the bearing led to the formation of high-density fine carbides in the microstructure of 100Cr6, which tends to decelerate the movement of dislocations during plastic deformation. Practical implications This study allowed the characterization of bearings wear in industrial mechanical systems. Originality/value Characterization of the bearings showed that the unusual hardening observed suggests that the damage was caused by the dissipation of a large surge of frictional energy lasting several milliseconds. The microhardness of the worn bearing is very high compared to the beginning wear bearing, which is due to the quantity of carbides formed. The thermo-mechanical stresses do not affect the main phases such as martensite, but they accelerate the fracture propagation at the surface.