Timken Super Precision Bearings for Machine Tool Applications

RUN-IN PROCEDURES
TAPERED ROLLER BEARINGS WITH SYNTHETIC
GREASE
The aim of run-in cycles is to correctly spread the grease inside
the bearing, to avoid churning of the grease and excessive bearing
temperature.
During run-in operations, the bearing temperature must be
constantly monitored and immediately plotted on a graph so that any
tendency of the curve toward a vertical asymptote can be averted.
Temperature probes, placed closest to the bearings, will provide
better control of the run-in operations.
The other advantage of the graph is to help determine the run-in
time at a given speed. When the curve becomes horizontal, it shows
that the temperature has stabilized. It is then possible to proceed
to the next speed.
The indicated times may vary depending on the speeds and heat
dissipation capacity of the spindles.
According to the results obtained on the prototype, it may be
possible to reduce either the number or the length (or both) of the
run-in steps for production spindles. In any event, temperature
control should be retained for safety reasons.
When running-in multi-speed spindles, reduced speeds must be
chosen at start-up of the cycles. The speed can be progressively
increased until the bearings evacuate any excessive quantities of
grease.
Time
Action
10 sec Run
1 min Stop
20 sec Run
1 min Stop
30 sec Run
1 min Stop
40 sec Run
1 min Stop
50 sec Run
1 min Stop
1 min Run
1 min Stop
90 sec Run
1 min Stop
2 min Run
1 min Stop
3 min Run*
1 min Stop
4 min Run*
1 min Stop
6 min Run*
1 min Stop
10 min Run*
20 min Stop
⇒ Then run until temperature stabilizes.
At this step of the cycle, as well as at the
other steps marked *, closely watch the
curve’s shape. If it tends to be vertical, stop
15 minutes and run again at 75 percent of
max. speed until the temperature stabilizes
again. Then restart the cycle from the
beginning at max. speed.
ENGINEERING
Table 15. Run-in suggestions for synthetic grease-lubricated
tapered roller bearings with single-speed spindles.
A
25% Max. speed 50% Max. speed 75% Max speed Max. speed
Time Action Time Action Time Action Time Action
1 min Run 1 min Run 1 min Run 1 min Run
1 min Stop 1 min Stop 1 min Stop 1 min Stop
1 min Run 1 min Run 1 min Run 1 min Run
1 min Stop 1 min Stop 1 min Stop 1 min Stop
2 min Run 2 min Run 2 min Run 2 min Run
1 min Stop 1 min Stop 1 min Stop 1 min Stop
3 min Run 3 min Run 3 min Run 3 min Run
5 min Stop 5 min Stop 5 min Stop 5 min Stop
⇒ Then run until
temperature stabilizes.
⇒ Then run until
temperature stabilizes.
⇒ Then run and closely watch the curve’s
shape during running, until stabilization. If it
tends to be vertical, stop 15 minutes and run
again at same speed.
⇒ Then run until temperature stabilizes.
At this step of the cycle, closely watch the
curve’s shape. If it tends to be vertical, stop
15 minutes and run again at 75 percent of
max. speed until the temperature stabilizes
again. Then restart the cycle from the beginning
at max. speed.
Table 16. Run-in suggestions for synthetic grease-lubricated tapered roller bearings with multi-speed spindles.
TIMKEN MACHINE TOOL CATALOG 61