Polyamide under-bonnet applications

In the automotive sector, engineering polymers such as polybutylene terephthalate (PBT) are replacing polyamide in some car electrical components because of their improved dimensional stability. Also, with the ever increasing temperature requirements in under-bonnet applications, liquid crystal polymer (TCP) and polyphenylene sulfide (PPS) have also been replacing polyamide [1]. 

Polyamides are used in a wide range of applications including under-bonnet applications such as the air intake manifold, and the air and cooling system peripherals. It is also used to manufacture electrical components such as switches, connectors and contactors. Applications are as diverse as castor wheels for furniture to aerosol valves. 

As an example of the complexity of organisational issues associated with Life Cycle Engineering, Figure 6.1 shows the possible stakeholders in a recycling scheme of an automotive under-the-bonnet application, in this case a radiator end-cap made from a reinforced polymer, short glass fibre-reinforced polyamide 66 (PA 66 + GF). 

Polyamide is used in all of the main automotive application areas. Under-the-bonnet applications is by far the largest area of application followed by electrical and lighting systems, exterior and interior applications. 

The main under-the-bonnet applications for polyamide include the air intake manifold, the air and cooling systems, peripherals, throttle body housing, the cylinder head cover, the water-glycol circuit and engine parts. High performance PA is also used to make tubing for under-the-bonnet applications such as fuel systems. 

Metal replacement has been a main driver for the use of polyamide in automotive applications in the past. Most of the obvious replacement of metal by PA has already taken place in the car interior, exterior and electrical systems areas. Under-the-bonnet applications however still offer some scope for further penetration by polyamide, particularly for high-performance grades. 

Polyamide is used for the manufacture of tubes for protection of wire and cables. Due to its high temperature resistance, flexibility and chemical resistance, PA tubes are mainly used in automotive under-the-bonnet applications. 

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