Ever wonder how 3D printers create a perfect rendering of whatever design you input into the computer? Notice how the nozzle moves back and forth smoothly while dispensing molten plastic layer by layer?
It’s all thanks to linear slides.
What is a linear slide? Also known as a linear guide or linear slide rail, it’s a machine element that allows free motion across a single axis. It’s responsible for the smooth, accurate, and steady linear motion you see in automated equipment.
On a 3D printer, for example, the components ride on electric linear slides for precise movements along the x, y, and z axes. Linear guides are also used in inkjet printers, CNC machines, and gantry robots.
How does a linear slide work? Keep on reading to learn more about the types of linear guides and how their engineering allows for perfect linear motion.
Components of Linear Slides
To understand how they work, let’s look at the general components of a typical linear slide system. They include the base, carriage, linear bearings, bellows and covers, impact dampers, and the drive unit.
The base or guide rail provides a stationary surface where the linear bearings can slide along a linear axis. The carriage is the moving part that supports the assembly that requires linear movement, for example, the print head of an inkjet printer.
The bearings are responsible for the free motion between the surfaces. Rolling elements are probably the type you’re familiar with, which include ball bearings and roller bearings. But they also come as plain surface bearings that rely on some form of lubrication for smooth motion. Examples of lubricants include pressurized liquid, dried air, and magnetic levitation.
Linear slide bellows and covers protect the guide rail from abrasive materials and debris. Impact dampers at both ends of the carriage provide a cushion in case of excess travel. And finally, the drive unit is what provides the forces to move the carriage, e.g., an electric motor or a pneumatic or hydraulic system.
Linear Slide Types
Engineers employ different combinations and configurations of components to serve a specific application. Some of the more common types of linear slides include:
Dovetail Slides
These slides are so named because of the dovetail-shaped protrusion at the base. The carriage provides the negative geometry to interlock with the dovetail base. The bearing is a plain surface type that relies on lubrication to reduce friction.
Boxway Slides
Boxway slides are also plain surface bearings with a “T”-shaped base. The carriage fits around the profile of the “T” rail. There’s a larger contact area between the two sliding surfaces, improving its capacity to support higher loads.
Linear Ball Slides
Ball slides are one of the most common rolling element types of slides. The ball bearings are either non-recirculating or recirculating (inside the carriage). Because it’s possible to deform the balls, they’re mostly used in applications with minimal shock, impact, and weight.
Slide to the Left, Slide to the Right
Linear slides travel only on one axis, either from left to right, up or down, or back and forth. The best-constructed slides follow a strict path with zero to minimal deviations. This level of preciseness is vital for the function of lathes, printers, and other automated machines.
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