Picture of Leine & Linde 500 series encoder with extended lifetime option.
How long should an encoder last in an industrial application? The answer is simple: as long as possible. Despite the difficulty in achieving this, a great advance has been made by the Swedish encoder manufacturer Leine & Linde.
Maintenance, machine downtime and loss of production cost the industry millions each year. Leine & Linde understand this, which is why we are proud to offer an option that provides extended lifetimes on our 500 series of rotary shaft encoders. Incremental speed encoders and absolute positioning encoders can be equipped with certain components including robust hybrid bearings from SKF, which together with many other lifetime optimizing measures, offer encoders an extended lifetime.
Hybrid bearings have rings of bearing steel and rolling elements of bearing grade silicon nitride (Si3N4). In addition to being excellent electrical insulators, hybrid bearings have a higher speed capability and will provide longer service life than all-steel bearings.
Excellent electrical insulation is one of the key features of silicon nitride. This protects the rings from electrical current damage and so-called washboarding, therefore increasing the bearing’s service life. Silicon nitride has a density that is just 40 % of bearing steel. The rolling elements therefore weigh less and have lower inertia. This means reduced cage stresses during rapid starts and stops and significantly lower friction at high speeds. Lower friction means cooler running and longer lubricant service life. Hybrid bearings are therefore suitable for high rotational speeds.
If there is insufficient lubrication, there is no smearing between silicon nitride and steel. This allows hybrid bearings to last much longer in applications operating under severe dynamic conditions or lubrication conditions with low operating viscosity.
Silicon nitride has a greater hardness and higher elastic modulus than steel. This results in increased bearing stiffness and longer bearing service life in contaminated environments. Silicon nitride rolling elements have a lower thermal expansion than steel rolling elements of similar size. This means reduced sensitivity to temperature gradients within the bearing and more accurate preload control.