A bearing can survive millions of load cycles in service but be destroyed in seconds during installation. Hammering a bearing onto a shaft, pressing on the wrong ring, or dropping a heated bearing are among the most common causes of premature bearing failure. Yet these installation errors rarely show up as the root cause on failure reports because the bearing runs for months or years before the damage from installation manifests as spalling or fatigue.
This guide covers the practical mechanics of pressing bearings on and pulling them off, when to use heat instead of force, and how to avoid the mistakes that plant maintenance teams make every day.
The Cardinal Rule of Pressing Bearings
The force must always be applied to the ring that has the interference fit. If you are pressing a bearing onto a shaft, the force goes on the inner ring. If you are pressing a bearing into a housing, the force goes on the outer ring. Never, under any circumstances, transmit installation force through the rolling elements.
When you press on the outer ring to mount a bearing on a shaft, the force passes from the outer ring through the balls or rollers to the inner ring. This creates Brinell dents (flat spots) on the raceways at each rolling element position. These dents cause vibration and noise immediately, and they become stress concentration points that initiate premature spalling.
For bearings that must be mounted simultaneously on a shaft and in a housing, use a mounting tool that applies force to both rings equally. These are available as purpose-built impact fitting tools or as simple tube sets that contact both rings.
Bearing Puller Force Estimator
Rule-of-thumb estimator for bearing removal and installation press force. Enter bearing size, fit tightness, and engagement length to get force estimate with tool recommendations.
When to Use Induction Heating
Induction heating is the preferred mounting method for medium and large bearings (bore above 60 to 80mm) or any bearing with a tight interference fit. The induction heater generates a magnetic field that heats the steel bearing ring uniformly to 100 to 110°C in 30 to 90 seconds. The ring expands, the bore opens by several hundredths of a millimeter, and the bearing slides freely onto the shaft.
As the bearing cools, it contracts and grips the shaft with the designed interference. The result is a perfect fit with zero installation damage, no Brinell dents, and no risk of cracking a ring.
Do not use a torch. Open flame creates uneven heating that warps the ring and may overheat one area while leaving another cold. Overheating above 125°C can temper the bearing steel and reduce its hardness. An induction heater with a temperature probe prevents overheating and ensures uniform expansion.
Do not use an oven for standard bearings unless the oven is clean and temperature-controlled. Bearings heated in dirty ovens can pick up contaminants. Oven heating is slow compared to induction, and the entire bearing assembly (including the grease, if pre-greased) reaches temperature.
• Target temperature: 100 to 110°C (212 to 230°F)
• Never exceed 125°C (257°F)
• Have the shaft, tools, and safety gear ready before heating
• The bearing cools quickly — you have 30 to 60 seconds to position it
• Push it firmly against the shoulder and hold until it grips
Bearing Removal Without Destroying the Shaft
Bearing removal is harder than installation because the fit has tightened during operation from seating, micro-fretting, and possible corrosion. A mechanical or hydraulic puller is the standard tool. The puller jaws grip behind the inner ring (for shaft-mounted bearings) and apply axial force to pull the ring off the shaft.
The critical mistake is gripping the outer ring when the inner ring has the interference fit. This pulls the force through the rolling elements, damages them, and then the inner ring still does not move because the friction force between the inner ring and shaft exceeds the pulling force applied through the rollers.
For large bearings or very tight fits, a hydraulic nut or oil injection method is preferred. The oil injection method pumps high-pressure oil between the inner ring bore and the shaft surface through a hole drilled in the shaft. The oil pressure expands the ring and reduces the friction coefficient, allowing the bearing to slide off with much less force.
Bearing Puller Force Estimator
Rule-of-thumb estimator for bearing removal and installation press force. Enter bearing size, fit tightness, and engagement length to get force estimate with tool recommendations.