In profiled rail linear guides that use balls or rollers, the geometry and arrangement of the bearing raceways play a significant role in the bearing’s load capacity, friction, rigidity, and ability to withstand errors in mounting. But there’s another aspect of a bearing’s design that also plays a role in its load capacity and rigidity […]
Crossed-roller slides
How to choose a lubricant for recirculating linear bearings
All metal-on-metal recirculating bearings require lubrication in order to function properly and provide a reasonable bearing life. Lubrication reduces friction and heat by separating the rolling elements from the bearing raceway, inhibits corrosion, protects bearing surfaces from contamination, and helps seals run smoothly and operate effectively. Although the importance of lubrication is clear, choosing the best […]
Mechanical properties of materials: Hardness
Hardness is a common specification for linear shafts and guides — especially those used with ball and roller bearings, where the guide encounters extremely high loads over very small areas. The hardness of a bearing surface can significantly affect the life of the system and is often accounted for by applying a hardness correction factor […]
What is cage creep and why does it matter?
Several types of non-recirculating linear bearings use a cage to contain the rolling elements, maintain consistent spacing between them, and ensure even load distribution. But in each of these non-recirculating designs, the cage “floats” between the two moving components, meaning that it’s not constrained and can gradually move away from its intended, centered position. This […]
Anti-friction miniature linear guides from PM B.V. now come with a variety of cage options
When building miniature linear-motion systems, design engineers can choose between ball and crossed-roller linear guides. When applied to precision systems, most all of these linear guides have cages to prevent shifting of the anti-friction rolling elements during operation … especially when these linear guides are applied in exacting microscopy, manipulator, and image-scanner applications — for […]
THK roller LM guide type HRX for myriad applications and harsh environments
A new Roller LM Guide Type HRX from THK America Inc. meets the demands of myriad applications and environments. The Type HRX boasts a duplex face-to-face structure (DF Structure) and a full roller design for resilient performance in even harsh settings. Features include a highly rigid, yet simple structure, caged rollers and an extensive dust […]
Why are cages used in crossed roller guides?
Crossed roller guides are non-recirculating linear bearings whose rollers are oriented in a “crisscross” pattern (each roller is turned 90 degrees relative to the one next to it) and move between two parallel guides with V-shaped grooves. Because the rollers don’t recirculate, these guides provide high load capacity and good stiffness, with smoother motion than […]
What are Hertz contact stresses and how do they affect linear bearings?
Linear bearings that use balls or rollers to carry a load are subjected to Hertz contact stresses — a type of material stress that plays a significant role in determining the bearing’s load capacity and fatigue life. When two surfaces of different radii are in contact and a load is applied (even an extremely small load), […]
Linear motion trends in slides: Robotics and mobile designs lead the charge
Demand for simple-to-install and pre-integrated linear-slide systems continues unabated … especially in applications only recently automated. Here’s the perspective of Matt Mowry, North American market manager for drylin products at igus: “We’ve supplied fully assembled and customized linear-slide tables … complete with motors and accessories. We’ve also supplied custom-extruded linear profiles and bearing liners to […]
What’s the difference between dynamic load capacity and static load capacity?
Rolling element linear bearings, such as round shafts and bushings, profiled rail guides, crossed roller slides, and even ball screws, have two load capacity specifications — dynamic load capacity and static load capacity — which are based on different operating parameters and performance criteria and are independent of each other. To accurately size and select a […]
