Linear bearing advantages

Back to Basics: Linear crossed bearings can deliver more precise motion control than spherical bearings, along with higher loads and greater rigidity.


Resin retainer fits around the roller so the whole shape can contact the load. Rollers can be closer.
Resin retainer fits around the roller so the whole shape can contact the load. Rollers can be closer.
Studs in raceway depressions prevent cage creep. Deeper V-grooves allow greater roller contact.
Studs in raceway depressions prevent cage creep. Deeper V-grooves allow greater roller contact.
Metal cages hold the rollers via a notch on the top and on the bottom of the rollers.
Metal cages hold the rollers via a notch on the top and on the bottom of the rollers.
Images courtesy of NB Corporation of America

Microprocessor manufacturing, diagnostic equipment and automation demand motion control with higher precision. In such demanding applications, linear crossed bearings can deliver more precise motion control than spherical bearings. For wafer manufacturing, robotics, vision inspection, and high-tech microscopes, crossed roller bearings or slides are increasingly used. In these crossed roller bearings, the cylinder-shaped bearings crisscross each other at a 90° angle and move between the two parallel guides. Rollers are positioned between “V” grooved bearing ways or raceways ground out of the guides.


More metal, greater loads


Roller-to-rail contact determines load capacity. Rollers provide a larger contact area than ball bearings and, since the rollers usually do not re-circulate, they all carrying the load, producing greater rigidity and higher load capacity than ball bearings. Because load capacity correlates with contact area, the small space between the rollers can make a 250% load difference. Metal cages hold the rollers via a notch on the top and bottom of the rollers. A resin retainer fits around the roller, offering a 30% to 58% increase of contact area, compared to a metal cage.


Metal cages, however, are less expensive, can be all stainless or steel, and can be used in high temperature or medical applications, with water and rust resistant potential. Resin can experience outgas situations—causing problems in high vacuum environments.


With crossed roller bearings, the assembly must be twice as long as the stroke because the rails move in opposite directions. A few crossed roller linear guide products have re-circulating crossed rollers that are not criss-crossed—four circulations with opposite roller orientations. Resin cage allows a longer stroke length on a given length rail because the cage can be shorter for a given load. There is little or no difference between static and dynamic frictional resistances.


For motion control applications with extremely fast acceleration and deceleration (at dimensions ranging from 30-600 mm lengths, 2-12 mm rollers) linear crossed bearings can endure 150 million cycles. Anti-cage creep mechanisms in crossed roller bearings designs can extend the life of guides and avoid readjustments caused by uneven preloading.


Larger contact area of crossed rollers provides consistently precise movement, and non-recirculation has less frictional resistance fluctuation, making them extremely quiet and smooth. Linear bearing rigidity means less mounting surface inaccuracy, up to 2 microns maximum of allowable deflection.


Author Information
Naoki Yamaguchi is assistant technical manager for NB Corporation of America, .

The Top Plant program honors outstanding manufacturing facilities in North America. View the 2015 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
Pipe fabrication and IIoT; 2017 Product of the Year finalists
The future of electrical safety; Four keys to RPM success; Picking the right weld fume option
A new approach to the Skills Gap; Community colleges may hold the key for manufacturing; 2017 Engineering Leaders Under 40
Control room technology innovation; Practical approaches to corrosion protection; Pipeline regulator revises quality programs
The cloud, mobility, and remote operations; SCADA and contextual mobility; Custom UPS empowering a secure pipeline
Infrastructure for natural gas expansion; Artificial lift methods; Disruptive technology and fugitive gas emissions
Power system design for high-performance buildings; mitigating arc flash hazards
VFDs improving motion control applications; Powering automation and IIoT wirelessly; Connecting the dots
Natural gas engines; New applications for fuel cells; Large engines become more efficient; Extending boiler life

Annual Salary Survey

Before the calendar turned, 2016 already had the makings of a pivotal year for manufacturing, and for the world.

There were the big events for the year, including the United States as Partner Country at Hannover Messe in April and the 2016 International Manufacturing Technology Show in Chicago in September. There's also the matter of the U.S. presidential elections in November, which promise to shape policy in manufacturing for years to come.

But the year started with global economic turmoil, as a slowdown in Chinese manufacturing triggered a worldwide stock hiccup that sent values plummeting. The continued plunge in world oil prices has resulted in a slowdown in exploration and, by extension, the manufacture of exploration equipment.

Read more: 2015 Salary Survey

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
The maintenance journey has been a long, slow trek for most manufacturers and has gone from preventive maintenance to predictive maintenance.
This digital report explains how plant engineers and subject matter experts (SME) need support for time series data and its many challenges.
This digital report will explore several aspects of how IIoT will transform manufacturing in the coming years.
Maintenance Manager; California Oils Corp.
Associate, Electrical Engineering; Wood Harbinger
Control Systems Engineer; Robert Bosch Corp.
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me