Compressors have been around for thousands (!) of years – as an indispensable aid in the production of high-quality metals. Modern screw compressors, on the other hand, are a relatively new invention from the 20th century. What distinguishes the technology in detail and where is it used today? Answers can be found here!
1. How exactly does a compressor work?
The literal meaning of the term makes the task of a compressor very clear: the machine increases the pressure and density of gases or air drawn in, whereby different designs are used. Experts distinguish between piston, screw and turbo compressors. In these machines …
- either pistons are used, which compress the air by moving it up and down,
- or the design consists of two parallel rotors (“screws”) with a helical profile that transports the gas further when they mesh and presses it against a wall. Alternatively, the gas pressure is ensured by an increasing pitch of the tooth profiles.
- Or the gas flows through various compressor stages (with small guide vanes), which are arranged one behind the other on a shaft. The whole thing is similar to an airplane turbine – only in reverse.
Basic principle of a turbocompressor: The compressor stages are arranged one behind the other on a shafts.
Source: NASA, Public domain, via Wikimedia Commons, https://upload.wikimedia.org/wikipedia/commons/c/ca/Axial_compressor.gif
2. Where is this technology used?
Compressors are available in countless designs and areas of application – the best known is probably the generation of compressed air, which is required for various cleaning processes in industry, during transportation or for the cooling system of components in production, for example. In fact, many manufacturing processes rely on compressed air. Think of painting systems, sandblasting or compressed air-powered impact wrenches. Last but not least, a compressor is installed in many motors. It supplies the drive with compressed air (and, therefore, more oxygen), which provides an additional performance boost.
3. Who invented it?
It may come as a surprise – because you wouldn’t immediately think of it – but the invention of the first compressor dates back thousands of years (!), as depictions of foot-operated bellows can already be found in Egyptian hieroglyphics. When mankind began to produce high-quality metals such as iron, the development of powerful compressed air technology of this kind was inevitable because it was the only way to generate very high temperatures of over 1,000 degrees. Some of the more advanced applications of compressed air are more than a hundred years old. For example, pneumatic brakes for railroads or pneumatic tube systems were already being used in the 19th century. It is no longer clear who was the first to develop a real compressor in its current form. In 1955, the Swedish engineer Alfred Lysholm succeeded in producing the first functional screw compressor – albeit without much success on the market, as the internal power losses at the screws were too great. The decisive breakthrough in this technology came around 40 years later with the use of oil injection in the compressor stage, which minimized the loss rate.
Illustration of a piston compressor from “Meyers Konversationslexikon” towards the end of the 19th century. The piston principle including push rods can be clearly seen here.
Source: Unknown author, Public domain, via Wikimedia Commons, https://upload.wikimedia.org/wikipedia/commons/9/96/Meyers_b10_s0995_b1.png
4. What does all this mean for the production of compressors?
The rotors and “screws” in particular are high-precision, high-tech products. The central component in rotary and screw compressors must be able to withstand permanently high loads and be resistant to locking – at extreme motor speeds of around 25,000 revolutions per minute. In addition, the profile shape is largely responsible for the performance of the devices. They are, therefore, manufactured with the highest precision, which is ensured by the final profile grinding process. In this context, EMAG has developed grinding machines specifically for this task. They score points with integrated processes – including fast format changes for a wide variety of workpieces. For example, a CBN grinding wheel is used for rough-machining and a ceramic grinding wheel for finish-machining. Both run directly one after the other.
Rotor of an air compressor, milled on an EMAG CLC 260 HW.
5. What does the future hold?
Digitalization does not stop at compressors. Manufacturers are working on real-time monitoring of processes, for example, with sensory equipment measuring the vibrations or temperatures that occur. The associated data can then be evaluated in order to detect anomalies at an early stage – especially in demanding application areas such as the energy and chemical industries, unplanned compressor failures should be avoided. At the same time, the focus is increasingly shifting to energy consumption. For example, the amount of electricity required can be reduced if the associated motor only provides as much power as the pump actually needs. In short: the compressor of the future is smart and green.
Profile grinding ensures high-precision surfaces for screw compressors. Machining on an EMAG GRX 500 H.
