A linear-motion bearing or as it is sometimes called, a linear slide is a bearing manufactured to provide free motion in one dimension. There are many different kinds of linear motion bearing and this group of products is usually separated into two sub-categories, that is rolling-element and plane.
Motorized linear slides such as machine slides, XY tables, roller tables and some dovetail slides are actually bearings moved by drive mechanisms. However, not all linear slides are motorized, and non-motorized dovetail slides, ball bearing slides and roller slides provide low-friction linear movement for equipment powered by inertia or by hand. All linear slides provide linear motion based on bearings, whether they are ball bearings, dovetail bearings or linear roller bearings. XY Tables, linear stages, machine slides and other advanced slides use linear motion bearings to provide movement along both X and Y multiple axis.
Rolling Element Bearing
Rolling element bearings are generally composed of a sleeve-like outer ring with several rows of balls retained by cages. The cages were originally machined from solid metal and were swiftly replaced by stampings. The feature smooth motion, low friction, high rigidity and a very long life. They are rather economical, and quite easy to maintain and replace. Thomson is usually given the credit for first producing what is known today as a linear ball bearing.
Ball Bearing Slides
Ball bearing slides are also referred to as "ball slides", ball bearing slides tend to be the most common kind of linear slide available. Ball bearing slides give the user a smooth precision motion along a single-axis linear design, assisted by ball bearings housed in the linear base, with self-lubrication properties that add to the reliability. Ball bearing slide uses include delicate instruments, robotic assembly, high-end appliances and clean room environments, which are normally used in the manufacturing industry but also the furniture, electronics and construction industries. A well known everyday example would be a ball bearing slide used as a drawer slide in the furniture industry.
These units are usually constructed from materials like aluminium, hardened cold rolled steel and galvanized steel, ball bearing slides are made up of two linear rows of ball bearings contained by four rods and situated on different sides of the base, which support the carriage for a smooth linear movement along the ball bearings. This low-friction linear movement is powered by either a drive mechanism, inertia or by hand. Ball bearing slides have a lower load capacity for their size compared to other types of linear slides because the balls are less resistant to wear and abrasion. Also, ball bearing slides are limited by the need to fit into housing or drive systems.
These are also known as crossed roller slides, roller slides are non-motorized linear slides that provide low-friction linear movement for equipment that is powered by inertia or hand. Roller slides are usually based on linear roller bearings, which are frequently criss-crossed to provide heavier load capabilities and better movement control. These units serve industries such as manufacturing, photonics, medical and telecommunications. Roller slides are very versatile and can be adjusted to meet many different applications which typically include clean rooms, vacuum environments, material handling and automation machinery.
Although roller slides tend not to be self-cleaning, they are suitable for environments with rather low levels of airborne contaminants such as dirt and dust. As one of the more costly types of linear slides, roller slides have the ability to provide linear motion on more than one axis through stackable slides and double carriages. Roller slides also offer line contact versus point contact as with ball bearings, creating a much wider contact surface due to the consistency of contact between the carriage and the base and resulting in far less erosion.
Dovetail slides, are usually constructed from cast iron, but can also be constructed from hard-coat aluminium, or stainless steel. Not unlike other bearings, a dovetail slide is composed of a stationary linear base and a moving carriage. a Dovetail carriage has a v-shaped, or dovetail-shaped protruding channel which locks into the linear base's shaped groove. Once the dovetail carriage is fitted into its base's channel, the carriage is then locked into the channel's linear axis and this allows free linear movement.
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