Compressed Air in the Machine Engineering Industry
Hardly any other industry is so significant and versatile as mechanical engineering. This branch includes production for both powered and driven machines, machine tools, conveyor systems as well as machinery for the automotive industry.
The application possibilities can also be varied and therefore also the requirements for compressed air. This is utilised e.g. for compressed air tools, plant and hoists, in cooling processes, for treating surfaces, for cleaning or also in higher quality as respiratory air.
Particularly reliable and stable processes are elementary in the field of mechanical engineering in order to ensure cost-effective production. Energy efficiency or the carbon footprint are also becoming increasingly important. Individual design of the compressed air processing and treatment is therefore necessary depending on the application and ambient conditions of the compressed air station.
Otherwise there is a threat of machine failure and product rejection, high energy and operating costs as well as reduced service life of the machines.
Applications in mechanical engineering
Compressed air tools are often preferred in machine engineering compared to electrical tools because they are easy to use, no need for electrical voltage and their low weight. Some applications require the compressed air as drive unit energy. This does not require high compressed air quality, the installation of a refrigeration dryer and filter is often sufficient. The correct design for the processing and treatment is however important, otherwise unnecessary energy costs will result.
Compressed air is utilised e.g. for cleaning workstations, plants, systems and machinery: when the air is depressurised by using a special nozzle, there is fast and strong flowing air. Liquids or particles can be blown away with this air flow.
Mechanical engineering without robotics is almost impossible today - this provides support for procedures such as welding, assembly, gripping and induction. For these processes, pneumatic components are required on stationary or mobile handling robots which then means that compressed air is an important part within the framework of control and drive for robots.
Other additional application areas for compressed air include e.g.:
Compressed air precision drill
Compressed air jack hammer
Compressed air brakes
Grinding, sheet metal processing and screwing with compressed air
Many production areas include tasks executed in the area of dust, paints and other - much more dangerous - substances. In such cases it is applicable that the employee executing the task is protected against aerosols and fine dust and corresponding health hazards. The people will be supplied with breathing gas via a respiratory protective device or must even, like astronauts, wear totally sealed protective suits. In order to save space, compressed air is often stored in bottles - utilising respiratory air compressors. The compressed air must comply with high purity criteria for use as respiratory gas. The individual limiting values with regard to residual oil content and degree of drying are specified in DIN EN 12021.
Cooling and heating air
Cooling and heating with compressed air is executed by utilising a so-called vortex tube, in which gases are separated through rotation in hot and cold air flows. The gases then subsequently exit according to their temperature condition through different sized holes.
If compressed air is also available in the works, then it is advisable to use it for this application since it is a very cost-effective solution. Compressed air is, for example, therefore advisable within the framework of metal cutting for the cooling of a drilling or turning machine, since the otherwise necessary cleaning of the adhering liquid refrigerant is no longer necessary.
Sealing gas / Inert gas
Compressed air can be utilised for contact-free sealing of plants, systems and jigs: The cavity will be sealed without friction and wear by utilising compressed air. Particularly in mechanical engineering, especially sensitive components and surfaces must be protected against dust, dirt, humidity or moisture. This is performed by creating a so-called air curtain above the surfaces.
Compressed air can also be utilised for inspecting seals and leaks.
Surface treatment: Compressed air blasting and painting
Compressed air can be utilised for applying abrasives and atomising colours within the context of surface treatments:
Compressed air blasting and/or grit blasting is the description for the surface treatment of a material or workpiece (blast quality) due to the effects of an abrasive agent. Sand is used as an abrasive agent against rust, dirt, colour, scale and other contamination or for surface design via matting.
Care must be taken when painting with compressed air to guarantee a high level of purity class and the limiting values with regard to particles, oil aerosol and oil vapour, silicone containing materials as well as condensate are complied with. Furthermore, no paint-wetting impairment substances (PWIS) may occur.
Additive manufacturing and 3D printing are becoming more and more important in mechanical engineering – not only for the preparation of prototypes but also as a serious, supplementary manufacturing technology. There are fields of application for 3D printing or additive manufacturing in many other industries, too, such as in plastic and metal production.
There are different methods and approaches used in the field of 3D printing to manufacture three-dimensioning objects. However, compressed air is not required for all of these. Compressed air is used for the laser methods (SLS and SLM) for example. With these processes, compressed air is routed through a generator to produce nitrogen at low cost. The inert gas gained in this way is pressed into the work chamber to protect the printed material from oxidation.
In addition, almost all 3D printers require a certain amount of post-processing, with considerable deviations possible between the respective procedure and the effort involved. Sometimes, it is enough just to remove residual powder using compressed air and to submerse the component in water; in other cases more complex procedures such as the separation of polymer support structures is necessary.
An important aspect that is often overlooked is the influence of compressed air on product quality and as a reason for downtimes. Because particles, humidity and oil vapour in the compressed air can interfere with the printing process and influence product quality.