Balls roll in four rows of raceways precision-ground on an LM rail and an LM block, and endplates incorporated in the LM block allow the balls to circulate. The raceways are cut into deep grooves
that have a radius closer to that of the balls than in the conventional design, using special equipment and an extremely precise cutting technique. This design allows high rigidity, high vibration/impact
resistance and high damping capacity, all of which are required for machine tools, thus making these models capable of bearing ultra-heavy loads.
* Due to the extremely high rigidity of the LM guides used in models NR/NRS-X, the construction does not easily absorb the effects of mounting surface misalignment and installation errors. Where such effects arise, there is a risk of reduced operating
life and/or malfunction. Contact THK when considering the use of these products.
While the machine tool (equipped with NR or NRS) is not cutting a workpiece during operation, the LM Guide travels normally and smoothly. While the machine tool is cutting the workpiece, the cutting
force is applied to the LM Guide to increase and the contact area between the balls and the raceway, allowing an appropriate mixture of rolling and sliding motions to be achieved. Accordingly, the
friction resistance is increased and the damping capacity is improved.
Since the absolute slip during the rolling and sliding motion is insignifi cant, it causes little wear and does not affect the service life.
The excessively large differential slip occurring in a Gothic-arch groove does not happen with these models. They smoothly travel and achieve high positioning accuracy during fast feeding. During
the cutting operation, appropriate slip occurs according to the cutting load, the rolling resistance is increased and the damping capacity is increased. Thus, models NR and NRS are highly rational LM
To increase the rigidity of the LM block and the LM rail, which may deteriorate the overall rigidity of the LM Guide in the reverse radial and lateral directions, THK made full use of FEM to achieve optimal
design within the limited dimensional range.
THK offers two identically sized models with different characteristics, namely the Radial Type Model NR-X and 4 way Type Model NRS-X. Users can select the model that best suits their specifi cations
Since the curvature of the raceway is approximated to the ball diameter, the ball contact area under a load is increased and the LM Guide is capable of receiving an ultra-heavy load.