Robust, wear-optimised guide systems in EME Parker linear actuators

Linear actuators with a conventional guide system can cause a variety of problems in a design, e.g. they often involve a large moving dead mass in the slider. In addition, there is an unfavourable leverage ratio between the support arm and load arm in the case of internal guides, as these are located far away from the load. The speed is limited (especially with recirculating roller bearing guides) and acceleration is restricted. Track roller guides in particular give way quickly under high moment loads – as track roller axles can be bent or misaligned, they are very susceptible. Not forgetting the lubrication usually required for these machine elements, which attracts dirt and can contaminate the entire system if grease or oil is discharged. They must be installed in a protected location or fitted with bellows as a cover. The regular maintenance required – usually cleaning and relubricating – also makes them expensive. Last but not least, the multi-part overall system means high assembly costs. Christoph Lindemann, Product Manager for Mechanical Components and Systems at Parker EME in Offenburg, also knows the risks and side effects in practice: "Our existing linear actuators are predominantly equipped with track roller guides. The track rollers are fastened to the slider with screws and eccentric bearings for clearance-free adjustment – a so-called "cantilevered fastening" is created. If the track rollers are already working close to their maximum load capacity during normal operation, a collision, for example, can easily lead to these fastenings becoming misaligned or even bent. Even short-term overloaded guides can therefore cause serious permanent damage to the entire system. The ratio of harmful to typical load is in the range of 3:1 and 5:1."

This is not the case with the drylin WQ guide systems from igus, which Parker EME installs in its "LCB" linear actuator. Here, this ratio is between around 100:1 and 500:1. These figures demonstrate the extreme robustness of the guides. After all, the slider transmits the forces directly to the guides. There is no possibility of misalignment and the risk of bending is practically eliminated.
The sliding elements are made of high-performance polymers. The use of iglidiur J material is recommended for most applications due to its wear and friction properties. The drylin linear bearing systems are generally designed for dry operation. Contamination from grease or oil is therefore a thing of the past. Ambient dust or abrasion during machining do not stick to the bearing point. drylin guides are divided into two main groups with different geometries: Linear guides and shaft guides.
In the drylin T system, the carriages run on a T-rail made of hard-anodised aluminium. All connection dimensions are identical to most commercially available recirculating ball bearing and guide systems. A miniature version can also be accommodated in the smallest installation spaces. Extremely flat "N" variants are available in four sizes from 17 to 80mm rail width. The carriages move in C-profiles made of anodised aluminium.
drylin R linear plain bearings, on the other hand, which correspond to the size of recirculating ball bearings, use round shafts as a mating partner. Different shaft materials are used here. Hard-coated aluminium shafts, for example, guarantee low wear and a low coefficient of friction. The drylin W linear guides used by Parker EME combine two round shafts, rectangular guides and the carrier profile for the linear actuator in one profile made of hard-anodised aluminium. They allow maximum design freedom thanks to different shaft diameters, profile widths, slide lengths and geometries.