Compressed Air In The Automotive Industry

The car has come a long way since the first Benz vehicle was patented in 1886. Originally hand-made from steel tubing and wooden panels, the car's construction evolved to include glass, rubber, copper, aluminium and steel panels. While much of the work continued to be done manually, Ford built the first assembly line in 1913, while after WW2 the Japanese were front-runners in developing automated production lines. Modern vehicles have replaced a lot of the less durable and heavier metals with lightweight, hard-wearing plastic composites.

As the materials and construction of cars developed, the use of compressed air for many of its processes became more widespread. Today, automotive industry uses for compressed air cover almost every aspect of the vehicle's life cycle. These range from engine construction and vehicle assembly to cleaning, finishing and painting, as well as the obvious everyday use of compressed air for inflating tyres. From the local body shop or tyre fitter to the vast corporate assembly lines of the leading manufacturers, compressed air is a key element in the automotive industry.

How Is Compressed Air Used In The Automotive Industry?

Over the past 100 years, automotive industry uses for compressed air have greatly enhanced the manufacturing process, increasing the safety of workers as well as the plant's overall efficiency. Compressed air tools help machines to cut, clamp and stamp out component parts such as panels, and they provide the power for machinery which lifts, moves, positions and fastens those parts together. Compressed air is also used to paint and clean vehicles, inflate car tyres and carry out welding and repair jobs in body shops and garages. Robotic machinery with pneumatic cylinders is used for all the strenuous work of vehicle assembly, and many compressed air applications are chosen for their greater precision.

Car parts need to be machined and cut to very precise measurements and tolerances. In the modern automotive industry, this precision is governed by automated programming. Computer-aided designs (CAD) are used by computer-controlled applications and pneumatic machinery to produce large numbers of identical products. There is a continuing drive to make car parts using lighter materials, such as thermoplastics, while at the same time ensuring they maintain their rigidity and strength.

Below, we’ll look at some typical automotive industry uses for compressed air.

Air-Operated Robots

In the earliest assembly stages, the bare shell of the car is put onto an air-powered conveyor system which moves it along the production line. Major components are installed on its journey, including the suspension, axles, fuel tank, brakes and steering assembly. Modern robotics obviate the need for heavy lifting by human operators, and robotic arms powered by compressed air can easily position and install the engine and transmission. Robotic machinery can also handle most of the other major components such as door pillars, side panels, quarter panels and roof pieces. Many of these pieces will have been cut and welded by air tools, aiding in the speed and reliability of assembly.

Air Tools

Compressed air tools are chosen for many tasks during the construction of larger components, including fastening bolts and screws with air-powered wrenches. Air ratchets can also be used to remove nuts and bolts, while an air-powered saw will carry out cutting and grinding operations. In fully automated systems, robotic arms with compressed air grippers are used for picking and placing individual components, particularly delicate items such as windscreens. In body shops, compressed air tools include air sanders for smoothing out rough metal pieces.

Plasma Cutters

Other uses for compressed air in the automotive industry include high definition plasma cutting machines. These can be hand-held torches or large-scale industrial machines, but they all work by forcing a stream of electrically charged compressed air or gas particles (the plasma) through a nozzle, and into the metal surface. This process, usually using nitrogen, is recognised to be more economical, safer and vastly faster than traditional metal cutting machinery.

Finishing

Once a new vehicle is fully assembled, it must be cleaned and painted – processes that both make use of compressed air. The car must be inspected for defects, making sure doors fit and work properly, seals are tight, and there are no uneven or damaged surfaces. Then it must be thoroughly cleaned before the paint can be applied, and the air supply must be checked for absolute purity. To get a perfectly even, mirror finish on the car when painting, the compressed air must be clean, dry, and free from oil and contaminants (see below). A contaminated air supply can cause significant problems, and will lead to spoilage, expensive re-working and production loss.

Paint Shop Work

Manufacturers, body shops and garages use low-pressure compressed air to propel paint through spray guns (perhaps using robots) onto the surface of the car body. Compressed air is also used in a paint bath, to agitate the contents and prevent the paint from clumping. In addition, this helps to mix the colour so it's perfectly consistent. To ensure that the paint spray is consistently reliable, it is critical to pair the spray gun or delivery system with the right type and size of compressor. Air dryers can help to achieve a smooth mirror finish, especially if the vehicle is customised with airbrushed painting.

Tyre Fitting

Tyre fitters use compressed air tools to remove wheel nuts, and screw them up again after the tyre is replaced. Compressed air is, of course, the means of inflating the tyre, which can also be done at most garages. The introduction of mobile compressed air units with on-board power means that tyre fitting can now be done on the roadside, instead of having to go to a workshop. Vans are also fitted with air jacks for raising a car off the surface, and a blast cage to ensure the safety of anyone in the vicinity should the tyre explode.

What To Consider When Using Compressed Air

Contaminant-Free Air

To ensure the smooth running of a compressed air system, it's essential that the air supply is always perfectly clean and dry, especially when applying spray paint and finishes. Solid particulates such as rust can clog up spray gun nozzles, as well as producing an imperfect finish. Oil in the air supply can cause paint to flake, crack or bead. It can also prevent paint from adhering properly to the surfaces, affecting the final finish and providing the potential for future corrosion.

Water particles in the air supply are equally, if not more damaging, blocking the compressed air's path and sticking to the walls of pipes. Moisture can get pulled back into the system, collecting in the receiver or at low points in the pipework, then squirting unexpectedly from a paint nozzle. On the final finish of a vehicle, water in the air stream can create unwanted textural and visual effects, such as spotting or ‘fish-eyes’.

Air Preparation

Contamination can damage downstream pneumatic equipment, leading to expensive production downtime and costly replacement of damaged equipment. In order to reduce the contaminants in a compressed air supply, it's essential to ensure the compressed air is properly prepared for use. This means installing and maintaining a filter, regulator and lubricator system, or FRL unit. This cleans the air, regulates the pressure and adds a necessary amount of lubricant to the final air supply so that actuators and power tools run smoothly. A compressed air dryer may also be employed when using spray guns, with coalescing filters to make sure any naturally occurring moisture is removed.

Energy Consumption

Using compressed air is a much cleaner form of energy, but in terms of cost, it's much less efficient. The amount of electrical energy required by a compressor to produce the compressed air is entirely out of proportion to the amount of compressed air actually produced, though there are initiatives that are beginning to address this. In most systems, only 10-20% of the electrical energy going into the system will reach the point of use, with the rest being lost in wasted thermal output and leakage.

It is possible to reduce the expense of an inefficient air supply. There should be regular inspections to identify and repair leaks, which can account for 20-30% of the energy lost in compressed air production. Check for leaks around pipe joints and couplings, condensate traps, pressure regulators and shut-off valves. Eliminating leaks can also reduce the pressure demand on the compressor. Adjusting its output controls can help reduce system run-time, prolong its working life, and generally cut down on its maintenance.

Evolving Processes

Advances in computer technology have made many vehicular processes more streamlined, and fully automated assembly systems now frequently replace human operatives. Part of this evolution is due to the use of high-quality compressed air, which is becoming cheaper, safer, and more energy-efficient than electric or oil-driven motors. Throughout the various production stages, automotive industry uses for compressed air help to make, position, and assemble car parts. It’s the driving force on the modern production line.