It may not be obvious to all, but linear guides can be found across the whole of industry. These motion-facilitating products are present in everything from machine tools, injection moulding machinery and food processing machines, through to packaging lines, semiconductor manufacturing equipment and medical devices. Without linear guides, the industrial world would, quite literally, grind to a halt.
Of course, not all linear guides are made equal. For applications demanding high-quality linear guides capable of delivering precision movement, high-load capability and excellent dust-resistant performance, expertly devised manufacturing processes and production technologies are required, such as those deployed by NSK.
NSK’s latest NH and NS series linear guides, which replace the previous-generation LH and LS series, are precision-manufactured in the UK, at the company’s state-of-the-art bearing plant and European stock facility in Newark, Nottinghamshire. Here, it is also possible to assemble bespoke units featuring specific carriage preloads or lubricant types, for example.
The NH and NS series are far more than mere revamps of the previous design. Although they are inherently suitable for high-speed applications, offer extended working life and accommodate higher loads, the new precision linear guides are designed to enable machine builders to either increase the performance of their products even further, or to downsize.
The option of downsizing is of great importance. Thanks to the higher load ratings of the NH/NS series, it is possible to replace the linear guides used previously with considerably more compact variants offering the same service life. By way of example, consider an LH30AN guide; engineers can now select the more compact NH25AN, which offers 20% less width and 10% lower height profile. Moreover, it offers a weight reduction of approximately 30% and costs less – all with no detriment to functionality.
In real numbers, the calculated service life of the NH25AN linear guide is 2.24 times that of the LH25AN, while noise levels drop by an average of 3 dB(A). Another benefit relates to speed: owing to the use of high-speed end caps, the maximum allowable speed has been increased by a factor of three compared with predecessor models. Instead of 100 m/min, the new NH/NS series is able to traverse at speeds up to 300 m/min.
As a point of note, NH/NS guides are dimensionally interchangeable with the previous LH/LS units, unless of course the downsizing option is exercised. The cost and space advantages associated with downsizing mean that numerous machine and equipment builders have been quick to take advantage.
Kevin Delehanty, Principal Application Engineer at NSK in Newark, explains some of the main appeal factors: “The new linear guides have a 30% higher dynamic load rating, which has been achieved thanks to geometrically optimised ball grooves. This design ensures a more uniform distribution of forces between the ball and the groove. Furthermore, the contact surface pressures for the same loading are significantly lower, allowing the dynamic load ratings to be revised according to the valid ISO guidelines. The result of the higher dynamic load rating is a doubling of fatigue life.”
Ultimately, the versatility of NH/NS linear guides means they can be employed in a wide range of possible applications.
“In principle, this covers all applications in which something moves and where precision, speed, service life and process reliability are important considerations,” says Mr Delehanty.
Such has been the impact of NSK’s NH/NS Series that the products recently won the Cho Monozukuri Innovative Parts and Components Award. Established by the Japanese government in 2004, this prestigious award recognises the valuable contribution that manufacturing makes to both industry and society. The judges said that the linear guides and the technology behind them earned the award by contributing to longer equipment lifespan and smaller system size.
NSK can of course complement the NH/NS Series with a range of supporting products for precision machine applications, including ball screws, ball screw support bearings and monocarriers.
The company’s ball screws feature cutting-edge tribology (friction control technology), and are available in sizes from miniature to ultra-large. The most recent development is the S-HTF Series, which offers more than double the service life and 1.3 times greater dynamic load capacity than the company’s previous-generation product. These performance attributes have been achieved thanks to the use of a new steel material (named Tough Steel – TF) for the screw shaft that delivers an optimised combination of hardness and resilience. S-HTF ball screws are intended for high-load applications, such as those found in plastic injection-moulding machines and forming presses.
Similarly, high-precision angular contact thrust ball bearings for ball screws have also been designed to suit specific applications. For instance, a special series for machine tools provides large axial rigidity and precise rotation with low starting torque, while a high-load capacity series for electric injection moulding machines offers enhanced service life through the use of an optimally designed ball diameter and contact angle.
Last but not least, NSK monocarriers represent lightweight, single-axis actuators with an all-in-one structure that integrates a ball screw, linear guide and support bearing. They are designed to provide long life and maintenance-free operation.
