Phenomenon (1): The raceway of the non-separable bearing has pits distributed at intervals between the rolling elements, as shown in Figure 58. Fatigue sometimes starts from these places, see section 3.3.2.1 of Fatigue Caused by Over Static Load. These pits may also be produced during disassembly: check the running characteristics (bright edges) and determine the installation direction. Reason: Static load overload/impact load Transmission of installation or disassembly force through rolling elements (incorrect installation sequence, inappropriate auxiliary equipment) Remedy: first install a tight-fitting ring. When both ferrules have a tight fitting fit, install them together with a suitable mounting plate. 37 Evaluate the running characteristics and damage of the removed bearings. Rolling contact mode 58: Ball pits on the ribs of deep groove ball bearings. The installation tool is in contact with the loose-fitting ferrule, so the assembly force is transmitted through the ball. 3.3.2.5 Pits and grooves caused by overcurrent Pits. Phenomenon (2): There are pits formed by partial melting in the contact area of u200bu200bthe raceway, sometimes there are several pits in a row or chain-like pits in the entire circumference. The surface of the pit is similar to spot welding, see Figure 59. Reason: sparks caused by current, such as during welding or due to failure of the grounding device. Remedy: avoid current directly passing through the bearing during electric welding (grounding). Groove. Phenomenon (3): There are many brown grooves parallel to the axis in the circumferential direction of a large part of the raceway or the entire raceway, as shown in Figure 60. Reason: AC or DC power continues to pass, even low current can cause traces. Remedial measures: Prevent current from passing through the bearing (grounding, insulation). Use insulated bearings. 38 Evaluate the running characteristics and damage of the removed bearing model. Rolling contact mode 59: The pits on the raceway of the cylindrical roller bearing formed by current spark discharge. 60: The groove on the outer ring raceway of the deep groove ball bearing is caused by the continuous current passing through. 3.3.2.6 Edge movement of rolling elements Phenomenon (4): There are arc-shaped indentations or wool ball-shaped indentations on the surface of the ball, and the edges are rounded due to plastic deformation, see Figures 61 and 62. For rollers, the circumferential indentation is close to the end face. Not to be confused with the scratches formed by foreign particles, see the scratches on the outer surface of the rolling body in section 3.3.4.2. Reason: Overload (axial) Torque load is too large The working clearance is too large. Tilting remedy: Avoid overload. Use bearings with high load-bearing capacity to reduce the working clearance. Avoid tilting. 39 Pair of removed imported bearings. Pattern 61: Edge marks on the ball surface caused by long-term continuous load 62: Ball-shaped indentations of wool on the ball surface formed by long-term varying loads.