Phenomenon (1): There are pits on the raceway of the non-separable bearing spaced by the rolling elements, see Figure 58. Fatigue sometimes starts from these places, see section 3.3.2.1 on Fatigue due to excessive static loads. These pits can also be created during disassembly: check the running characteristics (bright edges), determine the installation orientation. Cause: Static load overload/shock load Transmission of mounting or dismounting forces through the rolling elements (incorrect mounting sequence, unsuitable auxiliary equipment) Remedy: Install tight-fitting ferrules first. When both ferrules have a tight mounting fit, mount them together with a suitable mounting plate. 37 Evaluation of running characteristics and damage on dismantled bearings Rolling contact pattern 58: Spherical dimples on ribs of deep groove ball bearings. The installation tool is in contact with the loose fitting ferrule, thus transmitting the assembly force through the ball. 3.3.2.5 Pits and grooves due to overcurrent. Phenomenon (2): There are pits formed by local melting in the contact area of u200bu200bthe raceway, sometimes there are several pits in a row or chain pits in the entire circumference. The dimpled surface resembles a spot weld, see Figure 59. Cause: Sparks caused by current, eg during welding or due to grounding failure Remedy: Avoid direct current flow 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, see Figure 60. Cause: Continuous passage of alternating or direct current, even low currents, can cause traces. Remedy: Prevent current flow through the bearing (earthed, insulated). Use insulated bearings. 38 Evaluation of running characteristics and damage on dismantled bearing types. Rolling contact mode 59: Indentations in the raceways of cylindrical roller bearings formed by electrical spark discharges. 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 running of rolling elements Phenomenon (4): There are arc-shaped indentations or ball-shaped indentations on the ball surface, 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 scratches formed by foreign particles, see chapter 3.3.4.2 Scratches on the outer surface of the rolling stock. Causes: Overload (axial) Moment load too large Working clearance too large Tilt Remedy: Avoid overload Use high-capacity bearings to reduce operating clearance Avoid tilting 39 Evaluate running characteristics and damage to the removed imported bearings Mode 61: Edge marks on the ball surface caused by long-term sustained loading 62: Wool ball-like indentations on the ball surface caused by long-term varying loads.