Aligning a linear guide rail

Published by Emelie Neckman, 2024-09-10

Rails are manufactured using grinding machines. During the grinding process, the rail is fixed to the grinding bed with either screws or magnets. These machines offer extremely high precision.

Rails can be up to 6000 mm long, and the ball track tolerances must remain within just a few microns over the entire length.

Even with such high precision, it’s often the straightness of the machine frame that determines the final accuracy of the linear motion.

Rails can have either one or two high-precision reference surfaces. For rails with one reference surface, this side is typically marked with a line. Rails with two reference surfaces don’t need marking—you can mount them in either orientation.

There are four ways to mount a linear guide rail:

1. Mount the rail directly to a surface without any alignment (common in handling equipment)
2. Mount the rail against one reference edge (used when better tolerances or side load capacity is needed in one direction)
3. Mount against one reference edge and use clamps or wedges to press the rail into alignment (common in machining equipment for better tolerances and dual-directional side loads)
4. Mill an H6 groove in the base and press the rail into it (only possible with rails that have two reference surfaces)

Here’s a video on the topic featuring Carry Lindholm from Bosch Rexroth: