Linear actuators use a specific form of energy – hydraulic, pneumatic or electric – to produce linear motion. Over the past decades, Rotero has built up an extensive range, varying from actuators and ball screws to electric cylinders, lifting columns and slides. Innovations are regularly introduced in various areas, such as sustainability, compactness and accuracy. Consider the LMCA series from Unimotion, with a positioning accuracy of up to ±1 μm and accelerations of up to 10 m/s2…
Linear drives are used in many industrial and commercial applications. They are indispensable in the manufacturing industry, particularly in assembly and logistics departments. In heavier sectors such as the petrochemical industry and offshore, jacks are used to safely and accurately adjust the height of large drilling platforms. The same type, in a lighter version, can also be found for adjusting hospital beds or office furniture. And what about the high-precision ball screws that give CNC machines the high accuracy required for the precise machining of a wide range of products?
The best solution for every assignment
Ultimately, the application in combination with the environment in which it operates determines which linear drive is preferred. Hydraulic variants are used, for example, in applications where high power density is required. This quickly leads to the aforementioned heavy industries, hoisting applications or other heavy transport. Hydraulic variants can move accurately but are often more complex in terms of engineering. They also require many additional components, regular maintenance is important and there is always a risk of oil leakage.
Pneumatic systems are popular for applications in hygienic environments such as the food industry or pharmaceuticals. Pneumatic linear drives can also offer a solution in potentially explosive atmospheres. The installation often determines which choice is made. If pneumatics are already present, the choice for pneumatics is obvious. In other cases, this is not necessarily the case. Because air is compressible, these drives can often be overloaded for short periods without any problems. However, this same property also makes high-precision applications difficult. In addition, compressed air is one of the most expensive media in industry.
Rotero deliberately leaves the hydraulic and pneumatic variants to specialists in the relevant fields. On the other hand, specialist knowledge in electric drive technology is widely reflected in an extensive range of precision linear drives. The electric variant is also by far the most common. Although the initial costs (for purchase) are somewhat higher than the other two types, these versions can be controlled with extreme precision. This is certainly the case when using a feedback system such as an encoder that can provide feedback on position and speed. Electric motors are also available with both very small and very large power ratings, offering a suitable solution for a wide range of applications.
A special variant of the electric linear drive is the linear motor. This drive can be regarded as an unrolled electric motor that directly generates a linear movement without a mechanical spindle or belt. An example of a linear motor is the drive of the magnetic levitation train.
Sustainability and accuracy
Although most linear actuators are virtually fully developed, manufacturers of linear motors are not sitting still. They are participating in the industry-wide focus on sustainability. On the one hand, this translates into striving for lower energy consumption and, on the other hand, a longer service life. The first factor can be achieved by, among other things, using an electric motor with high energy efficiency and ensuring low friction through proper alignment and optimal lubrication. Gearboxes are often lubricated for life and no longer require specific (preventive) maintenance, making a service life of 30,000 hours no longer unusual.
Modules that can recover energy also contribute; the recovered (braking) energy is fed back into the grid or temporarily stored in, for example, a servo controller. A longer service life is achieved through the use of high-quality materials and (also) good lubrication, which minimises wear and tear.
Furthermore, the role of the control system is essential in maximising the efficiency of a complete drive. For example, by controlling the drives from a controlled motion profile, overloads of the mechanical system are avoided. There are no shocks, as is the case, for example, with the end stop of a pneumatic movement. This increases the service life, not only of the linear drive itself, but also of the driven load and associated guidance.
High power density
Technical developments have also led to ever-higher power density. This is one of the characteristics of the Unimotion LMCA series from the Rotero range. This means that these new linear motors enable efficient machine design as well as fast and accurate movements. In concrete figures, the positioning accuracy is 0.1 µm and the accelerations are up to 10 m/s2. These properties are based on a coreless design and direct drive. This makes the LMCA series particularly suitable for use in the laser industry, medical technology and electronics assembly, among other things. The absence of mechanical transmissions also contributes to a reduction in wear and maintenance costs.
The special properties are also related to the thermal efficiency of the motors. This helps to extend the service life of the motor and reduces the need for (external) cooling mechanisms. The low winding temperatures prevent overheating, which is a major advantage for laser welding applications. This is reinforced by the fact that the LMCA series is designed with remarkably low cogging torque. This promotes smooth and accurate linear motion, minimises vibrations and improves cutting accuracy.
The new Unimotion LMCA series linear motors have been specially developed for applications where high acceleration, precise positioning and reliability are essential – such as precision laser cutting. Accelerations reach up to 10 m/s².
Read about:
