Just two types of polymer resin-PBT, nylon (6 and 6.6)-account for over 90% of plastics applications in automotive electronics.
But in the past, the only black-coloured resins that could be laser welded have been PBT and Nylon 6.6. Not any more. BASF now claims that it has developed a laser weldable black Nylon 6 – the Ultramid B3WG6 LT – that is indistinguishable in appearance from normal black Ultramid grades.
Laser welding of thermoplastics offers a number of advantages over conventional welding techniques. Parts to be joined are not subjected to high mechanical loads, the amount of heat energy applied is small and localised, and laser welding is of course a contactless process.
Compared with Nylon 6.6 and PBT, the Nylon 6 base polymer has higher transparency to laser light, allowing short welding cycle times, more complex geometries and/or thicker walls.
The heat stability of Ultramid B3WG6 LT is also as good as that of normal Ultramid grades, which can withstand sustained service temperatures of 130 degrees C and short-term exposure of up to 150 degrees C.
One particularly interesting application area for the new laser-weldable Ultramid B is engine-intake modules, which are currently assembled by vibration welding. Unlike vibration welding, which leaves a rough burr of polymer at the mating surfaces, lasers produce clean, smooth joints and thus avoid the possibility of turbulent fluid flow in air or liquid carrying parts.
BASF expects many laser-welded production parts to appear with model year 2004.