This article explains step-by-step how to assemble a cross roller guide. These linear guides boast of unparalleled runout accuracy and are crafted to meet the most stringent of tolerances. As such, the assembly process demands attention to detail to achieve a successful outcome. It's important to read them carefully before you start. You need to be skilled to do this job well and avoid problems with the cross roller guide bearings. You should work in a room that's dry and free of dust, and away from machines that make metal chips or dust.
Before starting with the assembly of the linear guides kindly verify the following points.
Guide rails and roller cages need to be at room temperature;
Please verify the tolerances of the mounting surfaces to ensure that they conform to the prescribed tolerances for flatness and parallelism, as well as the angular error of the mounting and reference surface. De-burr and clean all elements, to ensure a flat surface and a perfect fit for the rails.
Make sure you have all the parts and tools you need. You need to use the right tools including a torque wrench, and measuring devices all the time. Precision linear guides are delicate, so be careful when you handle them. If you don't follow these instructions, it could affect the linear bearing performance and service life;
Remove the rust-protective oil on the rails and keep the rails and cages protected under a clean and dry cloth prior to installation;
To determine the location of fixing holes in the support structure (slide base) the holes in the rails should be taken as a reference and “copied” onto the support structure. This is highly desirable as the original pitch of individual holes may have altered during hardening by as much as 0.4 mm. To compensate for this, special attachment screws can be supplied on request.
Now, as a required first step, fasten the inner rail pair (marked as 1 in the figure). The base and reference face 1 of the linear bearing rails should be lightly oiled to prevent contact corrosion during operation. Then, both rails should be pressed against the mounting and reference shoulder. Subsequently, they can be fastened by starting from one end and proceeding towards the opposite end. The recommended torque must be applied, here the use of a torque wrench is recommended. It should be noted that the company logo and item number are marked opposite to the surface reference.
Parallelism of the V-groove of the rails (∆A and B) should be checked to ensure they don’t exceed the tolerance of the linear bearings (see graph on tolerances). After these steps have been followed, the slide element is ready for assembly.
The fixed bearing rail (2) should be mounted as described under step 3 above, but care should be taken not to tighten the adjustable rail (marked as 3 in the figure on the left side) too much, so as to leave a gap between the V-grooves for the insertion of ball cages, roller cages or needle cages.
If any end stop screws in the rail ends from where the cage is brought into the guide, are present, remove them now.
Carefully insert the cages. When placed in their exact position (mostly in the center), lightly secure the adjustable rail until the screws are finger-tight.
Fit the end screws or end pieces, and wipers in both rail ends.
The linear guide set is now ready to be backlash free-adjusted using the lateral preload set screws. The amount of preload is given in the product catalog. Here, the use of a torque wrench is recommended.
Before starting the preload procedure carefully move the slide top over its stroke length back and forth and feel that there are no irregularities.
Preload procedure: put the slide on a clean surface on its side with the lateral preload set screws up. Follow the below steps for the correct preload sequence.
Start in the middle position and adjust the set screws with the recommended torque value, working outwards from the middle. Notice: Only adjust the screws directly above the cage.
Move the slide top in one direction and adjust the set screws to the recommended torque value.
Move the slide top in the opposite position and repeat the adjusting for the screws which are now above the cages.
Again, move the top of the slide back and forth a few times and feel for no irregularities and that the movement is smooth and even.
Secure the attachment screws on the adjusting rail.
When assembly is complete, the linear guides must be checked for absence of play and inspected for running quality.
Click here to download the assembly manual for precision linear guides or anti-friction guides in PDF format.