What Is Brinelling? — Bearing Glossary

Brinelling is a bearing failure mode classified under ISO 15243 in which excessive static load creates permanent indentations on the raceway surface — causing noise and vibration from the very first rotation after the bearing is loaded.

The term comes from Johan August Brinell, who developed the Brinell hardness test. In bearings, brinelling occurs when static load exceeds the basic static load rating C₀ — the rolling element is pressed into the raceway until plastic deformation cannot recover. An indentation depth of just 0.0001 × rolling element diameter is enough to produce characteristic periodic noise and vibration.

Causes and Failure Mechanism

Brinelling appears in three typical situations: incorrect installation (hammer blows or press force applied through the non-fitted ring), shock loads during sudden machine starts, and transportation of stationary equipment exposed to vibration. The risk is highest when the bearing is stationary — no lubricant film exists to distribute load, so the entire force concentrates at the contact point.

The threshold for brinelling: static load P₀ > C₀/S₀, where S₀ is the static safety factor (typically S₀ = 1.0–2.5 depending on application) per ISO 76. Ball bearings are more susceptible than roller bearings because point contact produces higher Hertz contact pressure at the same load — the contact area is smaller, so pressure concentrates more severely. See all bearing damage modes in context at bearing failure modes guide and choose spherical roller bearings with higher C₀ for shock-load applications.

Distinguishing true brinelling from false brinelling matters for the repair decision. True brinelling produces bright, shiny indentations with no rust — pure plastic deformation. False brinelling produces reddish-brown indentations with Fe₂O₃ powder — fretting wear from vibration while stationary. Different mechanisms require different prevention strategies.

Practical Example: Bearing 6308 C3

At a cement plant in Hai Phong, a 6308 C3 bearing (d=40, D=90, B=23 mm, C=32.5 kN, C₀=19 kN) suffered brinelling after a technician drove it into the housing with hammer blows directly on the outer ring. Estimated impact force: 25 kN — exceeding C₀ by 32%. The bearing produced rhythmic noise immediately at first start-up. Vibration spectrum analysis detected peaks at multiples of rotational speed, confirming brinelling.

Correct installation for this bearing: use a mounting sleeve matching the 40 mm inner diameter bore, applying force only to the inner ring face via a hydraulic press. Maximum installation force ≤ 15 kN. Heating the inner ring to 80–100°C before fitting eliminates installation force entirely.

For precision applications (metrology equipment, medical devices), S₀ = 3.0–5.0 is required to keep indentations below the threshold that affects running accuracy. Standard industrial machinery typically uses S₀ = 1.5–2.0.

Comparison: Ball Bearings vs. Roller Bearings Under Static Load

The contact geometry determines brinelling susceptibility. Ball bearings (point contact) generate higher Hertz contact stress at a given load than roller bearings (line contact). A 6308 C3 ball bearing at 19 kN approaches its brinelling threshold, while a 22220 EK/C3 spherical roller bearing at the same load fraction has substantially lower contact pressure across the line contact zone.

For applications with high shock loads or vibration during standstill, roller bearings provide a significant safety margin. ZVL Slovakia manufactures both ball and roller bearings at their EU facility — with competitive European pricing compared to Japanese and German alternatives.