FEATURE BEARINGS, SEALS & GASKETS
DEVELOPMENTS IN BEARINGS
PIONEERING
continue to play a key role. For example, with the increased demand for industrial lightweight robots over the last few years, the use of needle bearings permits light and compact joint designs by means of downsizing. The needle bearings provide minimal variability and the highest level of safety. The most recent example is the angular
contact needle roller bearing XZU from Schaeffler, which is used both as an articulated arm bearing in lightweight robots and cobots, as well as the main bearing arrangement in the new RTWH precision gearbox, a ready-to- install reduction gear unit for robot joints.
SPEcIAL cOATINGS
With increasing demands being placed on bearings, it is often necessary for manufacturers to offer customers unique combinations of coatings for particular applications. Even for extreme applications, combined coating methods can be implemented. Surface technology is enabling the
customisation of surfaces for a specific purpose, including the provision of built-in ‘intelligence’ by adding sensory properties. Depending on the application, these surface layers can be water-resistant, or can provide reduced friction levels on mating components, or they can even protect metals from corrosion.
Insight into needle roller bearing production in 1950
Although the basic design of ball, needle and roller bearings has not changed significantly over the last few decades, developments in terms of the materials used, coatings and sealing technologies certainly have. These developments are providing benefits in the form of lower friction, less noise, longer operating life and more compact, space-saving, energy efficient designs, as Schaeffler explains
A
s any manufacturer will tell you, the demands being placed by customers have changed, even if the basic design of the
bearing has not. Specific applications now require higher precision, custom engineered, bearings that can handle increased dynamic loads and harsher operating environments, and which can fit into ever-decreasing design envelopes. Many applications also require lower friction
bearings that increase the energy efficiency of a machine or vehicle. As a result, bearing manufacturers now work more closely with customers than ever before, often collaborating much earlier in the design process.
cAGE-GuIDED NEEDLE ROLLER BEARINGS
With the invention of the cage-guided needle roller bearing in 1949, Dr.-Ing. E.h. Georg
Schaeffler eliminated the serious disadvantages associated with the full complement needle roller bearings that had previously been used as standard. The development of the new needle cage overcame these disadvantages, such as the substantial amount of sliding friction generated between the rollers, and the skewing of the rollers causing the bearing to jam. This permitted considerably higher speeds and less friction. Engineers could substitute other bearing designs for cage-guided needle roller bearings and significantly improve the performance of their applications. Although needle roller bearings made an
invaluable contribution to the development of small, high-performance and affordable vehicles over the years, their use in industry has increased dramatically and in the future that won't change. Needle roller bearings will
22 DESIGN SOLUTIONS JULY/AUGUST 2021 MATERIALS AND hEAT TREATMENT
In recent years, there has been a significant increase in the demand for rolling bearings that, even under extreme operating conditions – including lubricant starvation, highly corrosive or high temperature environments – provide a long operating life and optimum performance. Depending on the application and the specific environment in which the bearings will operate, a suitable material or heat treatment process for rolling bearings can be chosen. There is a key role here for the type of
materials used for the various bearing components (i.e. rings, rolling elements, cage, etc.) and how these interact. Some of these materials are industry-recognised standard steels (in rolling bearing quality), but others may need to be specially developed by the manufacturer or may involve special surface or heat treatment processes to give the material a
Replica of the first cage-guided needle roller bearing from Schaeffler
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