Timken Super Precision Bearings for Machine Tool Applications

A
ENGINEERING
TIMKEN ® SUPER PRECISION BEARINGS
Manufacturers require machine tools that are extremely accurate,
reliable and capable of high levels of productivity. A major
contribution to the performance of any machine tool is supplied by
the rolling bearings used to support the spindles, rotating tables,
ball screws and other critical precision positions. A manufactured
bearing’s precision level has a major influence on the ability to
perform in high-speed applications commonly seen in factory
machining environments.
WHICH TYPE OF TIMKEN BEARING IS MOST
APPROPRIATE FOR YOUR MACHINE TOOL
APPLICATION?
To achieve the highest possible performance precision level, the
majority of machine tool-related bearing applications must address
four primary requirements: speed, stiffness, accuracy and load
capacity.
Speed
Today’s industrial machining environments stress maximum
production rates. To reach these high metal-removal goals,
machines are operating at maximum speeds with working spindles
tuned to provide premium running accuracy.
Achievable spindle rotating speeds require management of heat
generation within the bearing assembly. The bearing’s ability to not
only minimize heat buildup, but also expel excess heat, is a crucial
consideration in the bearing selection process. Because of the
differences in rolling element contact geometry, ball bearings are
superior in minimizing heat generation, especially where higher
speeds are desired.
Max Speed (RPM)
14000
12000
10000
8000
6000
4000
2000
Tapered Roller Bearing (TS Metric)
Ball Bearing (2MM9100WI)
0
70 100 130 160
Bore (mm)
Fig. 1. Tapered roller bearing vs. ball bearing maximum permissible
speed (with synthetic high-speed grease).
Timken offers a wide range of
products targeted for improving
machining efficiency, cutting
accuracy, and productivity.
Qualified sales and service
engineers are available to help
determine an appropriate solution
for individual applications.
Figure 1 compares the relative maximum speed of similar cross
section ball and tapered roller bearings (both using synthetic
grease as a baseline lubricant). Therefore, in applications where
higher RPM levels are the primary concern, ball bearings have a
distinct advantage.
Bearings must be carefully designed to minimize heat generation
and vibration to enable high speeds. Specific strategies include
overall bearing configuration, precision internal geometry
and material selection. Optimizing bearing ring and shoulder
construction with the ball complement supports higher speed
performance. Engineering raceway and ball geometry helps to
minimize friction, while ceramic rolling elements generate less heat
with reduced skidding.
To prevent vibration at high speeds, close bearing tolerances are
required. Timken ® machine tool bearings are designed to meet or
exceed industry tolerance standards and deliver smooth running
performance.
In addition to the use of hybrid ceramic technology, further
enhancements in speed, as well as control of bearing noise and
temperature, can be achieved through cage design or material,
and choice of lubrication.
16 TIMKEN MACHINE TOOL CATALOG