Many different factors come into play when creating a telescopic linear movement. Is it a horizontal or vertical movement? What is the surrounding environment like? These are some of the factors. It is therefore wise to first make a thorough assessment of all available relevant information.
Requirements analysis of telescopic movements
Depending on the function of the telescopic linear movement there are different requirements. Therefore, the first step is always to make a thorough assessment of all demands. It is important to take all factors into account, not just the most obvious ones, such as loads and speed requirements. The surrounding environment, for example, is highly significant when choosing construction and suitable materials. Water, humidity, sawdust and temperature are important for material selection and possible enclosures. If the telescopic linear movement is to be enclosed, limitations in the physical space also have an impact on strength and function.
The application sets the requirements
An important consideration is where and how the movement should take place. Telescopic movements are mostly used for manual applications without heavier loads and a lower number of cycles, for example filing cabinets or chest of drawers. Automated applications used in the manufacturing industry and constant motion in stressful environments require a more robust construction.
In the manual application, aluminium or sheet steel may be sufficient for the rails, when there are light loads and low stress. In industries with large loads and often strong vibrations, the rails need to be manufactured in hardened cold-drawn carbon steel, which is significantly stiffer and can handle heavy loads even when fully extended.
In these cases, the extension rails also need to be made of hardened steel to ensure smooth movement regardless of vibrations, shocks or shock loads.
Most telescopic applications are driven by cylinders which are intended for applications with few points of contact. But for precision applications that require exact movements, such as pick and place, telescopic belt-driven actuators can contribute to optimally controlled movement.
The surrounding environment affects
Depending on the application environment, there are different needs. The ambient conditions affect, for example, the choice of materials and which surface treatments are required. If it is a humid or otherwise corrosive environment, where the components are exposed to e.g. corrosive liquids, cleaning agents or frequent cleaning, it may be a good idea to invest in stainless steel or chemically nickel-plated rails. In a less exposed environment, rolled steel or aluminium may be sufficient, if the loads and precision requirements allow. Even the type of lubrication grease is affected by the surrounding environment. Lubricants have different properties and temperature tolerances, so depending on whether it is high or low temperature, make sure to select grease with suitable properties.
Horizontal or vertical
Another factor that affects the design is whether the telescopic linear movement should be horizontal or vertical. Since vertical movement naturally tends downwards, it is more challenging and requires special solutions. One way is to move slower by increasing the preload. Then the movement is controlled and intact. Another solution is to design the telescopic rails so that they can extend in both directions and always expand the rails to their end positions. Depending on the conditions and the application, there are various suitable products.
