Colourful safety connectors

Wiring harness connections are one of the most complex assemblies in electric vehicles. The large number of connectors used not only need to be coloured differently to differentiate between the various functions and to facilitate assembly and maintenance, but also need to be highly flame retardant and mechanically stable. The polyamide 6 compound Durethan BKV30FN04. a material developed by LANXESS for these connectors, has been repeatedly tested in numerous applications, including harness connectors for electric vehicles produced by a European and American car manufacturer. ‘Compared to polyamides that use red phosphorus for fire protection, our halogen-free flame-retardant polymers can also be dyed in bright colours such as orange (RAL 2003) and yellow.’ Bernhard Stoll, a LANXESS expert working on the use of plastics in electrical and electronic components, said. ‘Both the compound and the colour are highly thermally stable, which means that the different (coloured) joints can be easily and reliably distinguished throughout the vehicle's life cycle.’ The connectors were manufactured by Amphenol-Tuchel Electronics GmbH in Heilbronn, Germany, a subsidiary of Amphenol, a leading global manufacturer of electrical connectors headquartered in the United States.

The connectors made from Durethan BKV30FN04 are used in cable harnesses for electric vehicles produced by a European and American car manufacturer. The halogen-free, flame-retardant polyamide 6 can also be dyed in bright colours such as orange (RAL 2003) and yellow, and has high strength and toughness. Image: LANXESS Chemical

Included in the ‘Yellow Card’ as ‘All Colours’.

LANXESS polyamide 6 compounds have excellent flame retardant properties. The compounds achieved a V-0 rating (test body thickness: 0.75 mm) in the UL 94 flammability test conducted by the US test institute Underwriters Laboratories Inc. ‘Our compounds are listed by UL in the ‘yellow card’ for ‘all colours’, which also includes yellow, orange and blue. This means that processors don't need to colour their products or have them undergo time-consuming UL certification. They simply use our pre-coloured compounds, which reduces costs.’ Stoll said.

Superior performance

Harness connectors are distributed throughout the length and width of a vehicle, bundling a variety of different on-board power supply cables used for power converters, battery charging systems, electric drives, infotainment systems, and other electrical and electronic functions. The total length of the cables can be several kilometres, which is one reason for the large weight of the cable harnesses. The complexity of cable harnesses makes them extremely expensive components, so the connectors must never break during installation. ‘Our compounds are extremely robust, which means that the joints can easily withstand being bumped or dropped.’ Stoll said. The thermoplastic is highly resistant to chemicals, which means its strength and stiffness are virtually unaffected by contact with dielectrics or coolants. It also has excellent resistance to electrical traces, with a CTI (relative trace index, IEC 60112) value of 600 (orange).

Wide processing window

Durethan BKV30FN04 can be used for joints in electric mobile travel as well as in signal transmission technology and industrial engineering. ‘Within a wide processing window, our compounds prove suitable for stable injection moulding. The material's flame-retardant additives leave virtually no deposits on the mould, which helps ensure long tool life and efficient production.’ Stoll said. In terms of occupational health, polyamide 6 is easier to handle than other polymers that use red phosphorus for fire protection.