The difference between linear rails and hard rails

The difference between linear rails and hard rails

Structure:

Linear guides are modular linear guides, consisting of slide rails and sliders. Inside the sliders, there are balls or rollers. They are standardized products that can be directly installed on machine tools and are easy to replace when worn.

The hard rail is a casting part where the guide rail and the bed are integrated, processed, quenched and ground. There are also steel-inlaid guide rails that are nailed to the bed and use sliding friction.

Performance:

Linear guides feature rolling friction, with a low coefficient of friction, high running speed, fast idle travel speed, capable of high-speed cutting up to 1.5g, feed rate exceeding 60m/min, no crawling phenomenon, low temperature rise during continuous processing, and good precision stability.

Hard rails are subject to sliding friction, with a large coefficient of friction and limited movement speed, up to a maximum of 15m/min. Crawling is prone to occur, and the temperature rise during long-term heavy cutting exceeds 15℃, requiring a cooling system.

Precision:

After the linear rail is pre-tightened, there is zero clearance. The positioning accuracy is ±0.002mm per full stroke, and the repeat positioning accuracy is ±0.001mm, which is 2 to 3 times that of hard rails.

Hard rails can only move when there is a gap on the moving surface. They have a large friction coefficient and are prone to sticking, which leads to processing errors.

Vibration resistance:

After effective treatment and pre-tightening, the linear guide rail has higher rigidity than the hard rail during long-term operation and better retention of processing accuracy.

Lifespan and Cost:

Under the same conditions, the linear guide has a long service life, low maintenance cost and is easy to replace.

The wear-resistant layer of the hard rail needs to be repaired 2 to 3 times. The total life cycle cost is 40% to 60% lower, but the maintenance difficulty and cost are high, and it may be necessary to re-cast the bed casting.