Let us first understand what a linear motion guide is. It is simply a machine element that uses bearings developed for rotary motion. The sole purpose of an LM guide is to move heavy objects linearly in an effortless way. Other names for LM guide are “linear motion ball guide” or “linear bearing,” giving a sense that it is for linear motion and not for rotary motion. Know more about LM Guide HSR Bearings (ตลับลูกปืน LM Guide HSR, which is the term in Thai) here.
Let’s understand the structure of the LM Guide.
Structure
The Linear Guide Is Mainly Composed Of Three Elements:
- Mobile Carriage
- Rail supporting the movement of balls and carriage
- Lastly, a mechanism is attached to enable recirculation of the balls.
Let’s now have a look at the history of the Linear Motion Guide.
History
It was in the United States when the ball bushing was developed as the first linear motion guide in 1944. The ball bushing comprised balls as elements to roll between a cylindrical sleeve-type nut. The infinite linear motion is enabled when the balls recirculate by the movement of the nut.
There was a flaw in this mechanism due to the low load capacity, as the balls made point contact with the nut and shaft in a small area. Also, it was observed that the nut rotates when a torque works on the post, which requires two or more shafts to avoid the balls losing track and going out of the destined travel direction. This issue required a massive area for the smooth operation to happen.
This challenge was later overcome with the development of a ball spline. It featured an arc-shaped raceway grated into the nut and shaft. This improvement enabled the change of the contact point between the raceways and balls into surface contact, resulting in larger loads by the ball spline than ball bushing.
It also eliminated the problem of the balls leaving the track, and no extra shaft was needed. The purpose was solved with a single shaft, transmitting enough torque for the smooth motion.
Conclusion
The modern linear motion guides are more efficient and intelligent. Linear motion guides are a part of our daily life. They play an essential role in bearing loads to enable the precise and efficient operation of the machines. They are also used in semiconductor manufacturing tools and machine tools. The typical linear motion guide usage applications are buses, railways, automatic doors, seismic isolation systems and many other consumer sectors.