The benefits of composite materials in connectors

For many people, ‘plastic’ means ‘cheap and breakable’. But when engineers search for new ways to enhance weight savings, corrosion resistance, shock and vibration dampening and stealth, they immediately turn to plastic - the only alternative material capable of meeting, and beating, the established performance of aluminium, brass, titanium and steel.

The name plastic refers to the ability to form or shape a material, or to the ‘mouldability’ a material adopts under forces such as pressure or heat. Engineers often use the term ‘polymer’ when referring to plastic materials, because it more clearly describes how many (poly) chemical units (mers) form up in complex chains to create modern plastic resins.

Polymers can be reinforced with glass, minerals and conductive and nonconductive graphite fibres to meet a diverse range of mechanical, physical, chemical, thermal and electrical requirements. While certain fibre additives provide additional strength, others address electromagnetic and radiofrequency shielding. Additives can also be used to increase flame retardency, to improve lubricity or, in the case of pigments, simply to change the colour of the final product.

Several factors, including the environmental drive to develop cadmium-free alternatives to plated-aluminium parts, have contributed to the wider use of composites. Other important benefits of composites over metal materials include corrosion resistance, vibration dampening, weight reduction and stealth. High-temperature plastic is not sacrificial to plating, so composite products last longer and require less maintenance than metal components such as the above.

Corrosion resistance: One of the most appealing attributes of composites is their unlimited corrosion resistance as compared to conventional materials. Aluminium interconnect components, for example, are subject to galvanic coupling which causes the metal material to be ‘sacrificed’ to its cadmium/nickel plating. Since high-temperature plastic is not sacrificial to plating, finished products last longer, require less maintenance and directly reduce the overall cost of ownership of the interconnect system.

Vibration dampening: Another benefit of composite thermoplastics is vibration dampening. Unlike metals, polymer plastics are less subject to harmonic resonance due to their lighter weight and inherent attenuating properties, which means threaded components made from these materials are far less likely to vibrate loose when subjected to prolonged periods of vibration and shock. Again, reduced maintenance and reduced cost of ownership are the major benefits realised by systems built from vibration-dampening thermoplastics.

Weight reduction: The typical weight savings for composites over aluminium is approximately 40% (depending on component design). Weight savings versus other materials are even more pronounced: 60% for titanium, 80% for stainless steel and 80% for brass.

Stealth: The reduction of magnetic, corrosion-related magnetic and acoustic signatures is critical to the development of stealth applications. The reduction of these signatures can improve survivability of military systems, leading to improved effectiveness and fewer casualties.

Glenair (distributed in Australia by ConnectorTech)