Linear Bearings
Linear
bearings are used where something needs to be moved along a straight line
with high precision in one direction, and if required move back to it's
starting position.
Hardness, finish, and conformity of race and rolling elements determine
load capacity. The surface finish must be smooth because grinding marks
create ridges that prevent conformity between the race and rolling element.
Flat race, balls have lower load capacity than rollers. The circular groove
has a higher load capacity, but the ball bears on the bottom of the groove,
which results in side play. Preloading can damp the vibrations caused due to
deflection but this also increases drag friction.
Choices for linear bearing styles include air, flat ball cage, ball spine,
ball bushing, needle roller cage, cam follower, crossed roller, guide wheel,
hydrostatic, plain or journal, linear motion guide, flat roller cage, and
linear roller. Bearing materials for linear motion bearings include bronze,
ceramic, graphite, plastic, and stainless steel. Special material features
include corrosion resistance, self-lubricating, and rotary motion.
Important specifications to consider when selecting linear bearings include
the bearing width, length, inside diameter, and dynamic load capacity. The
bearing housing can be flanged, none or open, rectangular, and pillow block.
The bearing may be open or closed. Features and options for linear bearings
include adjustable preload, clean room use, lubrication port, self-aligning,
vacuum compatible, and wipers or seals.
