In addition to filtration, the plastics technology of MANN+HUMMEL has a huge potential to increase the efficiency of modern engines. The use of technical plastic parts by the Ludwigsburg company goes right back to the seventies.
Just like our petrol pump attendant, I can well remember the large metal box which served as an air cleaner in my first car. Mounted right on the top of the engine, it could be unscrewed to remove the air filter so that you could tap it out at the side of the road and then refit it. In 1968, MANN+HUMMEL presented the world’s first air cleaner made from plastic and in the nineteen seventies and eighties gradually replaced the metal housing of existing air cleaners with plastic. Then in 1984 the first oil filter made from plastic followed. Those were the first parts produced in plastic by us at MANN+HUMMEL.
Weight, costs, flexibility
The changeover from metal to plastic addressed the three main points of weight, costs, and, most importantly, flexibility of design. The use of plastic allows the manufacturing of products with almost any complex design. Whereas with metal we would roll and stamp the manufacturing material to make the part, with plastic we pour the molten plastic into a mold and so it does not matter whether the plastic flows into a mold with a simple or complex geometry. If we take a look today into the overcrowded area of the engine compartment of a car, we see the air cleaner has a complex design to enable it to hug other parts with just a gap of a few millimeters. This kind of flexibility would be almost impossible using metal.
We have also been producing dirty and clean air ducts in plastic for air cleaners since the end of the eighties. They direct the intake air to the air cleaner and then take the filtered air to the engine. The result was the development of complete air intake systems. A further step was then the inclusion of the intake manifold, the final component which distributes the clean air to the cylinders in the engine.
If you could imagine being an oxygen molecule, you would only see MANN+HUMMEL parts on your way to the engine. That was real pioneering work. In 1989 we were the first company in the world to produce an intake manifold in plastic and in 2003 also the first to present an oil filter module with an all plastic housing.
Naturally, the increasing complexity of our products has led to higher requirements for materials and production processes. The plastics have to be resistant against oil, fuels and alcohols, whereby even cooling water can be very aggressive. An intake manifold, for example, has to be mechanically robust to provide support for the mounted parts, e.g. a heavy part like a throttle valve. As a result we work with very high quality plastics such as polyamide, PPA and PPS which maintain their function even at temperatures over 200° C.
We know from our everyday life that plastic parts age and become brittle when you purchase a cheap part. That cannot be allowed to happen with our parts. They have to work perfectly over long periods in the harsh environment of an engine. That means in summer the plastic has to handle temperatures in direct sunlight of up to 100°C and in winter temperatures down to 40°C where combustion takes place in an ice cold engine. So we are not talking about a plastic ruler on the office table, but rather about technical plastics which have to meet extremely high requirements.
Another example is the air ducting after the turbocharger. Today most new cars are fitted with a turbocharger. The turbocharger compresses the air and therefore the ducts downstream of the turbocharger have to be able to withstand very high temperatures and pressures. Apart from that, the ducting in the crowded engine compartment is complex. That may sound trivial, but in fact it is not.
Since the middle of 2014 we have also been producing a plastic switching valve which regulates the cooling water circuit. The plastic here has to be resistant to the glycol in the cooling water and also remain absolutely stable. This is the only way to ensure that the valve will switch with the necessary precision over a long period of time. Other manufacturers use aluminum to achieve this whereas we are able to exploit the advantages of using plastic.