What Are the Four Forms of Slewing Bearing Raceway Failure?

The service life of the slewing bearing is jointly determined by its own product quality and subsequent maintenance. Even some believe that "three-tenths of quality and seven-tenths of maintenance." After the raceway is damaged and fails, several phenomena generally occur: large clearance, oil leakage, sticking, abnormal noise, iron powder or even iron blocks. There are many reasons for bearing failure, and today SWBTEC will introduce four common forms of failure of the slewing bearing. It is for learning and understanding.

Failure mode of slewing bearing: raceway wear

The relative sliding friction between surfaces causes continuous wear and failure of the metal on the working surface. Wear will cause the fit clearance to increase and the surface shape of the raceway to change, and it will also affect the lubrication function of the lubricant, causing the bearing to lose rotational accuracy or even cannot operate normally. Raceway wear is divided into normal wear and abnormal wear. Normal wear is the process of gradually increasing the clearance during the full service life cycle and completing the full life cycle task. Abnormal wear is related to manufacturing problems, standard parts problems, lubricating grease problems, and after-sales maintenance problems. The first three problems are related to the slewing bearing manufacturer, and the fourth situation is the problem of the equipment user.

Failure mode of slewing bearing: plastic deformation of raceway

Under external forces, local plastic flow or overall deformation of the surface of the part, such as deformation of the raceway or twisting and warping of the cage, etc., which cause the slewing bearing to not work normally and cause failure. This situation often occurs after a period of use. At this time, the high-hardness layer has mostly worn out, and the metal on the inner and outer sides of the raceway is squeezed into a pile after bearing load and friction suddenly increase. A steel grade with high hardenability should be used instead.

Failure mode of slewing bearing: raceway surface peeling

The main reason for the peeling of the raceway surface of the excavator slewing bearing is that the hardened layer is too thin and the hardness transition zone is too narrow. There are many reasons that can cause contact fatigue failure, which may be caused by excessive axial load, poor lubrication, poor alignment, and excessive impact load during installation, etc. A medium-frequency device with a lower frequency should be selected to deepen the hardened layer. At the same time, the quenching hardness should be appropriately increased to reduce the hardness gradient of the raceway cross-section.

Failure mode of slewing bearing: raceway corrosion and pitting

The surface damage caused by the chemical or electrochemical reaction between the metal surface and the environmental medium is called corrosion failure. Corrosion is divided into three types: chemical corrosion, electrochemical corrosion, and microvibration corrosion, mainly manifested as the rusting of internal bearing mating surfaces. The invasion of corrosive media, the condensation of moisture in the air, the generation of sparks when current passes, and micro-vibration can all cause the raceway of the slewing bearing to corrode and fail. The situation of pitting mainly occurs on the quenched and tempered raceway. The reason is that the hardness is low and the raceway structure design is unreasonable, which causes sliding friction and contact fatigue stress, resulting in defects such as pitting and indentations.

These are the introductions to the four common forms of failure of slewing bearing, to avoid such failure phenomena, regularly carry out reasonable and effective maintenance work on the slewing bearing, which not only can reduce the occurrence rate of failures but also can extend the service life of the slewing bearing.