Forced fracture
Stress exceeded strength: the ring or cage simply broke. Urgency
The steel could not carry the stress: broken in one event, or cracked progressively.
What forced fracture looks like
- A crack or break through a ring, flange or cage, often at an edge or where an impact or stress raiser sits
- Rough fracture faces with little sign of slow crack growth
- Chipped corners, broken ribs, or a ring split clean through
Rotec AI schematic illustration. It shows the typical pattern and is not a photograph of a real bearing.
How forced fracture develops
A local stress above the steel's strength opens a crack in a single event: a heavy blow, a ring forced onto an oversized seat, or balls climbing over the raceway edge under extreme misalignment. Through-hardened rings are hard and brittle, so tensile stress makes them snap rather than bend.
How fast it progresses: Sudden. The bearing usually fails at once or on the next start.
Causes of forced fracture
Mounting, handling & storage
- Hammering or brute force; mounting on an oversize shaft or too far up a taper
Design & seats
- Fit too tight, causing excessive hoop stress
Operating conditions
- Severe shock, jamming, or extreme misalignment pushing elements over edges
- A seizure that breaks the cage
How to confirm it is forced fracture
- Check shaft diameter and fit tolerances against the drawing
- Examine the fracture face: a single-event break looks rough and abrupt
- Check the mounting record and the tools used
How to fix and prevent forced fracture
- Select the fit for the real load and verify the seat dimensions
- Never use brute force or load through the rolling elements
- Use suitable tools and control drive-up on tapered seats
- Fix misalignment before it overloads an edge
Easily confused with
- Fatigue fracture: Fatigue fractures show progressive beach marks and grew over time; forced fractures look abrupt.
Worth knowing
Lip and flange fractures
Supporting lips broken partly or completely come from an axial load that is too high, a lip that is not supported, an axial shock load, or damage during mounting. Make sure the lip is well supported by the design, keep the axial load within limits, and follow the mounting instructions.
Other fracture modes
Questions about forced fracture
What causes forced fracture in a bearing?
Hammering or brute force; mounting on an oversize shaft or too far up a taper. Fit too tight, causing excessive hoop stress. Severe shock, jamming, or extreme misalignment pushing elements over edges.
How do you fix or prevent forced fracture?
Select the fit for the real load and verify the seat dimensions. Never use brute force or load through the rolling elements. Use suitable tools and control drive-up on tapered seats.
What does forced fracture look like?
A crack or break through a ring, flange or cage, often at an edge or where an impact or stress raiser sits. Rough fracture faces with little sign of slow crack growth.