ISO 15243 Bearing Failure Modes During Operation - Part 3
ISO 15243:2017 classifies the failure modes of bearings installed in equipment during operation, excluding manufacturing defects such as partial imperfections. The standard categorizes failure modes into six major classes: rolling contact fatigue, wear, corrosion, electrical pitting, plastic deformation, and cracking & fracture.
Descriptions of the six failure modes are as follows:
Plastic Deformation (ISO 5.5)
Overload Deformation (ISO 5.5.2)Mechanical damage caused by static overload. Common causes of static overload include improper handling (e.g., bearing dropping from height), incorrect installation (e.g., hammering the bearing), and impact loads during equipment operation. Manifestations include raceway indentations, depressions corresponding to the spacing of rolling elements, and damage to cages, seals, or shields.
Particle Indentation (ISO 5.5.3)Occurs when solid particle contaminants or debris are excessively crushed in the rolling contact area of the bearing, resulting in indentations (deformation) on raceways and rolling elements. The extent of damage depends on the size, type, and hardness of the particles. Sustained rolling over indentations can lead to surface-originated fatigue (ISO 5.1.3).
Cracks and Fractures (ISO 5.6)
Overload Fracture (ISO 5.6.2)Occurs when the stress exceeds the material's tensile strength. Common causes include an excessively tight interference fit, or excessive advancement of a tapered bore bearing on a tapered journal or adapter sleeve, which generates excessive hoop stress.
Fatigue Fracture (ISO 5.6.3)Occurs under cyclic bending conditions when the stress exceeds the material's fatigue strength. Repeated bending causes cracks to initiate and propagate on the rings or cage. Fatigue fracture may occur in bearings subjected to heavy loads if the supporting stiffness of the housing is insufficient, leading to high cyclic stress on the outer ring.
Thermal Cracking (ISO 5.6.4)Occurs when two surfaces slide against each other, generating frictional heat. If sliding is severe, local secondary hardening of the surface occurs; combined with the propagation of high residual tensile stress, this leads to cracks—typically perpendicular to the sliding direction. For example, thermal cracking can occur when a stationary bearing housing contacts a rotating bearing ring.
