THK LM Bushings provide accurate straight motion for applications

November 9, 2022

It can be used in applications such as slide units of precision equipment, including OA equipment and peripherals, measurement instruments, automatic recorders and digital 3D measuring instruments, industrial machines that include multi-spindle drilling machines, punching presses, tool grinders, automatic gas-cutting apparatuses, printing machines, card selectors and food packing machines. 

The Linear Bushing’s straight motion is created due to the ball bearings, which are located in the loaded area of the nut, being in point contact with the LM shaft. 

It also creates the least friction resistance and very accurate and smooth motion, regardless of the small permissible load. 

The nut’s inner and outer surfaces are heat-treated and then ground and it uses high-carbon chromium bearing steel. 

The dimensional tolerances of the Linear Bush’s components are standardised and are therefore interchangeable. The LM shaft is easily machined through cylindrical grinding and allows very accurate fitting clearance. 

The retainer plate accurately grinds ball bearings in the travelling direction as it is integrally moulded and guides three to eight rows of balls. The small-diameter types use integrally moulded retainers that are manufactured with synthetic resin and it reduces noise-generated during operation and allows for excellent lubrication. 

Users have a large variety of types to choose from. They include the standard, clearance-adjustable, open, long and fitted flange types, as well as flanges linear bushing.

Dedicated LM Shafts 

As the ball bearings roll directly on the LM shaft, it has to be manufactured taking into account hardness, surface roughness and dimensional accuracy. 

An LM shaft’s surface hardness has a significant impact on the service life of a Linear Bushing system and, therefore, it is recommended that specific attention be given in selecting a material and heat treatment method when assembling the system. 

 Additionally, caution must be given when selecting or handling a material and heat treatment.