Bearing assembly (pressing a rolling bearing into its housing or onto its shaft, with the force on the right ring and the press-fit curve checked)
Press-fitting rolling bearings into housings and onto shafts · force through the interference-fit ring only, tools on both rings when both are tight, hammer limits, force-displacement windows and end-point detection
Bearing assembly here is the step in which a rolling bearing is pressed into a housing or onto a shaft on an assembly line or workbench: a press and tool push on the ring that has the interference fit until it seats, and a force and displacement record shows whether the fit and seating were right. Ask three things first: which ring has the interference fit, how the tool carries force to that ring and not through the balls, and how the press detects that the bearing is home without crushing it.
Press-fitting of rolling bearings into housings and onto shafts: fits, mounting tools, press force path and force-displacement monitoring of the press-fit step. Servo press modules and joining actuators are covered on the Servo motor actuator for press-fitting page; furniture hinges on the Furniture hinge page; slewing bearings, wheel hub bearing units and bearings sold alone are outside this page.
CNFX editorial research · Sources checked October 12, 2026 · 3 sources
SKF states that "poor fitting, usually using brute force, accounts for 16% of premature bearing failures", and that when bearings are mounted cold "the drive-up forces are applied to the ring with the interference fit"; if the force passes through the rolling elements, the raceways can be damaged. Its TMFT 36 kit uses impact rings matched to the bearing's inner and outer diameters (bores of 10-55 mm, outer diameters of 26-120 mm) and sleeves to carry force evenly to that ring, and the impact rings can be used under a press. [1]
NSK describes press fitting as "widely used for small bearings": for a tight inner ring the tool sits on the inner ring and the bearing is pressed slowly until it rests on the shaft shoulder, oiling the shaft seat first, and "the mounting tool must not be placed on the outer ring during press mounting". When both rings of a non-separable bearing such as a deep groove ball bearing are tight, a tool bears on both rings and they are pressed at the same time with a screw or hydraulic press. A hammer should only be used for small ball bearings with minimally tight fits when no press is available, always through a mounting tool on the inner ring. [2]
Give the assembly equipment supplier the bearing type and size, which ring is tight and the fit tolerances of shaft and housing, whether both rings are tight, the part that receives the bearing and how it is held, the press type and force range, the tooling contact faces, the monitoring and traceability needed, and the cycle rate.
02
Force-displacement windows and catching the end point
An HBM article in Reliable Plant explains the windowing method: force and displacement are recorded through the press-fit cycle and the curve must pass through prescribed force/displacement windows for the part to be approved, while the system stops the press "at the exact split-second the bushing or bearing is pressed home, or the part can be crushed". The end point shows as an exponential rise in force that "takes place in less than a millisecond". It describes simultaneous sampling of force and displacement every 50 microseconds through a three- to five-second cycle, and a powertrain line pressing 6,400 cycles a day with forces from 0 to 15,000 N, tolerances within 0.003 in and forces within 3% of nominal. [3]
Editorial calculation: sampling every 50 μs over a 4-second cycle gives 4 ÷ 0.00005 = 80,000 force-displacement pairs, while the line described tracks 200 points along the curve; HBM also notes a transmission line making 3,000 units a day with four to six press-fitted bearings each, which is 12,000 to 18,000 bearing press fits a day. [3]
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
Which ring should the press push on?
SKF and NSK both say on the ring with the interference fit; force through the rolling elements damages the raceways. [1][2]
What if both rings are tight?
NSK says use a tool on both rings and press them at the same time. [2]
What share of bearing failures comes from mounting?
SKF says "poor fitting, usually using brute force, accounts for 16% of premature bearing failures". [1]
How does a monitored press know the bearing is seated?
HBM describes an exponential rise in force at the end point, under a millisecond long, inside an end window on the force-displacement curve. [3]
Sources and what still needs a direct check
Sources checked 2026-10-12. SKF publishes its TMFT 36 fitting tool data (distributor copy); NSK publishes bearing mounting guidance; Reliable Plant carried HBM's article on press-fit monitoring.
