Linear Bearings

About Linear Bearings and Linear Bearing Manufacturers Including: Linear Ball Bearings, Linear Motion Bearings, Linear Roller Bearings & Slide Bearings.

Linear bearings are often used when an object needs to be moved along a straight line with high precision in an industrial or manufacturing setting. The object being moved on the linear bearings generally only needs to be moved in one direction which makes the function and design of these linear bearings simple. The movement is produced with a high amount of repetition and fluidity. Basically, linear bearings provide a sliding or rolling contact between the object being moved and the bearing, creating relative motion among parts of the machine. Linear bearings are especially useful in applications that involve high accuracy and short travel, as well as degrees of noise, vibration and accessibility.
 
Linear bearings are a type of linear slide. These linear bearings use bushings, balls, slides, rails and grease and vary in size and strength. Linear bearing manufacturers produce many different types of linear bearings used in conjunction with larger automated systems, such as positioning tables and robotic assisted assembly lines. One of these types, linear ball slides, is compact and has a small form factor and a short stroke. These slides have the ability to stroke up to one-third of the slide length. Crossed roller bearings, on the other hand, have a much larger load capacity than ball slides because of the contact line between each roller and the raceway.
 
There are many common uses for linear bearings. They can be found in drawer glides and work station height adjustment mounts. The materials that linear bearing manufacturers make these kinds of bearings are usually plastic or low grade metal because of the minimal stress that is exerted upon the linear bearings. Occasionally these are referred to as linear guides, but mostly they are used as part of an industrial motion control system, along with devices such as linear actuators. Other, more general uses for various types of linear bearings include optic alignment, disk certification, precision dispensing, vision inspection, wafer testing and handling, precision gauging and automated production equipment.
 
Linear bearings are easy to install and are typically low cost. Because there are so many linear bearing manufacturers, standardization is not often found. Special consideration should then be made to determine what a bearing’s width, length, inside diameter and load capacity needs to be for the specific application. Linear bearings can be made of materials such as bronze, plastic and stainless steel. Some of the linear bearings styles are self-cleaning and lubricating, while others need to be cleaned and lubricated with regularity to ensure successful utility.

Linear Bearings and Linear Bearing Manufacturers Images Provided by Del-Tron Precision, Inc.

Types of Linear Bearings

• Ball screw bearings have a helical inner race that converts torque to thrust as the screw and nut turn and the component moves in a linear direction.
  
• Crossed roller bearings are one of three primary types of linear bearings. They have more load capacity than ball slides because of the contact line between each roller and the raceway.
  
• Flat ball cages are a linear bearing design in which the balls are trapped in a frame that spaces them at equal distances.
  
• Flat roller cages are similar to a crossed roller bearing, but the axes to all the other rollers are parallel instead of crossed.
  
• Gonio way bearings are curved to mimic the arc of a pendulum.
  
• Linear ball bearings use spherical parts to separate moving parts along a straight line.
  
• Linear ball slides, often referred to as "linear slides," are compact forms of linear bearings with small form factor and a similarly short stroke. Maximum stroke can be about one-third of the slide length, but the form factor justifies the stroke.
  
• Linear motion bearings are used to bear loads and direct linear motion.
  
• Linear roller bearings are ball bearings used to separate parts.
  
• Positioning stages or tables are comprised of two basic components: a precision linear slide (ball or cross roller), which serves as a linear bearing and guide, and a drive mechanism, which accurately moves and positions the slide top along the linear axis.
  
• Rotary linear bearings/slide bushings are used when accurate linear movement of a large object is required. These devices consist of a cylinder with circulating balls, which is attached to a shaft and is able to slide up and down the shaft and rotate around the shaft itself at the same time.
  
• Slide bearings use metal plates to resist friction.

Linear Bearings Terms

Axial Clearance – The amount of play or movement displayed when a bearing’s inner ring is moved axially in relation to the outer ring.
 
Basic Dynamic Load – The load under which a bearing can operate while rotating.
 
Bearing Analyzer – A device used to measure a bearing’s performance, and for fault analysis after use.
 
Bearing Cage – A device used to separate the rolling elements of a bearing (also known as a retainer).
 
Brinelled – The result of rolling elements being forced onto inner or outer raceways, leaving indentations in the raceway which lead to premature bearing failure.

Carrier – Responsible for supporting and moving the load. Carriers are commonly attached to the linear slide with a bearing system.
 
Gib – A wedge-shaped piece of metal or wood designed to hold structural parts in place and/or provide a bearing surface.
 
Graphitic Corrosion – The deteriorization of bearing housings in grey cast iron products.
 
Grease Pocket – A special design feature of a cage/retainer that allows grease to accumulate and then slowly be fed to the rolling elements.
 
Load Rating – The maximum amount of weight that a bearing can withstand.
 
Lubricant – A substance is used to lubricate the moving surface of a bearing, protect against corrosion, conduct and transfer heat and keep contaminants from entering.
 
Pear Skin – A term that refers to the “fuzzy” appearance of the load-bearing surface of a bearing, which is caused by contamination.
 
Raceway – The portion of the bearing in which the ball or other part slides. Raceways provide the track of confined movement for the bearing mechanism itself.
 
Radial Clearance – The space between the rolling elements and the races in an unmounted bearing, designed so that the bearing has the necessary net clearance to operate.
 
Seal – A device to stop the ingress of contamination and the escape of lubrication.
 
Stay Rod – The long fasteners used to hold the retainers together when riveted retainers are used in a maximum bearing capacity.
 
Tensile Strength – The ratio of a material's strength to its cross-section.
 
Tribology – The study of friction, lubrication and wear on two moving surfaces in contact.
 
Weibull Distribution – A statistical analysis tool that is used to study bearing life and calculate the probability of failure.