Plastic: Material with a Future

Plastic is increasingly gaining acceptance in thermal management: from surround seals to fan wheels, from cooler tanks to HVAC modules. For this reason, the Competence Center Plastics has been formed under the leadership of Snjezana Boger. All Behr’s expertise related to plastics is to be pooled under this umbrella. “This new field takes into account the increasing significance of plastics at Behr”, explains Boger. Another aspect is that the properties and processing of plastics differ immensely from aluminum, for example. The complete plastics process includes:

• processing methods (e.g. MuCell®, welding, etc.)
• tools and machine technology (e.g. injection molding machines including peripheral equipment)
• method development (validation processes)
• materials

In conjunction with suppliers, Behr develops a suitable material and machinery plus peripherals for the respective application. As an example, the specification profile for materials used in the engine coolant circuit is very exacting. Plastic used there has to

• be resistant to media in the engine compartment and to the hot coolant, i.e. it must not become brittle or corrode in contact with the coolant
• have good mechanical properties, i.e. it has to be sufficiently rigid, insusceptible to creep and withstand impact
• heat resistant, i.e. it must not age prematurely under heat nor warp
• be easy to process

All these requirements are verified in initial tests and subsequently validated in the laboratory facilities. Once this step is completed, the process parameters for the working of the material into a component can be established. On the basis of performance specifications, the machine required for the process is defined and an inquiry is submitted to the appropriate supplier in conjunction with Purchasing. The principle is basically the same for the necessary tools. As the dimensioning of a component is also influenced by the properties of the used material, the competence center provides support to ensure that the design engineers come up with feasible solutions for plastic. The simulation of the filling process is gaining in importance in this respect. The heating of a tool can be computer-simulated - a useful method when it comes to the dimensioning of tools and components.

The future and new trends in plastic

What are the latest developments? “A trend toward high temperature resistant plastics is emerging. These are used in charge-air coolers, for example, which are increasingly being fitted in turbocharged Otto engines”, states Boger. The problem is that in some engine versions the aggressive exhaust gas condensate comes into contact with the cooler. For this reason, it must be made sure that the used plastics are also resistant to this contamination. New materials must also meet other requirements: in Russian and Asian regions calcium chloride is frequently used to de-ice the roads in winter. However, this corrodes polyamide so this plastic material has to be suitably stabilized. At the same time, work in being carried out on the development of new, more resistant materials.

In the case of HVAC systems, on the other hand, factors such as reduced weight, odor neutrality and good acoustic properties are the main issues. A reduction in weight is attained, for instance, by expanding the plastic. “Another key issue will be the recyclability of the used materials”, adds Boger. “For this reason, work is already being carried out on gaining raw materials from plants for the production of plastics.”