Chemical firm Lanxess has developed three new compounds suited to laser plastic welding.
In addition to good, process-safe laser-weldability, the new materials possess a range of other properties that enable them to be used in the manufacture of a broad range of components, including those for electrified vehicle drives and driver assistance systems.
High hydrolysis stability with good weldability
The first compound, Pocan B3233XHRLT, is a new, 30 per cent glass-fibre-reinforced PBT (polybutylene terephthalate) compound that exhibits good laser transparency and an excellent resistance in a hot and humid environment. According to Lanxess, such materials are almost unprecedented on the market, as standard additives for hydrolysis stabilisation generally cause the laser transparency of PBT to deteriorate significantly.
The exceptional hydrolysis resistance of the new compound has been demonstrated in the SAE/USCAR-2 Rev. 6 long-term tests of the American Society of Automotive Engineers (SAE).
‘This test on the finished part is recognised worldwide as the ultimate test of hydrolysis resistance,’ said Dr Claudia Dähling, an expert in technical plastics at Lanxess. ‘In a series of highly stringent, in-house tests conducted on test specimens, our product achieves USCAR test results of between Class 4 and 5 – the two highest classes.’
Flame-retardant and laser-transparent
The second compound, Durethan BKV30FN04LT, is a halogen-free material based on polyamide 6 which offers flame-retardant properties. This is particularly desirable, as according to Lanxess, most flame retardants will diminish the laser transparency of thermoplastics.
The new material passes the UL 94 flammability test of the US Underwriters Laboratories testing organisation for small test specimen thicknesses, with the top classification of V-0. The material can be safely processed within a stable process window and leaves hardly any deposits in the tool. Its high tracking resistance of 600V (CTI A, Comparative Tracking Index, IEC 60112) makes it ideal in for use in components for high-voltage batteries and plugs – such as those in electric vehicles.
Tailor-made for greater wall thicknesses
The third new compound develop by Lanxess for laser plastic welding is Pocan TP150-002, a 30 per cent glass-fibre-reinforced PBT compound optimised for extremely high laser transparency. It exhibits a transmission of 13 per cent, which is around double the transparency of most other laser-transparent PBT product types (measured with a LPKF TMG-3 device at 980nm and a test specimen thickness of 2mm). The material was tailor-made for the cost-efficient laser welding of components requiring a greater wall thickness.