Munich, Germany - The PolyBright research project has demonstrated laser welding of commercial components from several industries such as automotive, medical, and white goods manufacturing. In the latter, after part selection, preparation of the polymer masterbatch by Treffert, injection molding and part machining by Electrolux, the welding was carried out using Fraunhofer ILT's TWIST setup, on PolyBright WP5 prototype machines.
Compounds for a door handle and cover (Fig. 1) are supplied by Treffert: 1. PC, white cover on ABS, white door handle, and 2. PC, grey cover on ABS, grey door handle. Polymer compatibility is ensured for the PC-ABS combination. Welding at 1567 nm is preferred compared to the regular fiber laser wavelength of 1060 nm, due to higher transmittance and lower reflectance for the upper cover part. The measured optical properties of the grey 2 mm PC cover are shown in Figure 2.
The cover's thickness has to be reduced from between 1 to 2 mm to avoid unwanted burning effects at the top surface during processing. Important welding parameters are laser power of 30 W, welding speed of 15 mm/s, beam diameter of 1.8 mm (estimated), TWIST frequency of 1000 Hz, and TWIST radius of 0.5 mm.
Electrolux is the white goods manufacturer, Treffert is the compounder, and PolyBright project coordinator is the Fraunhofer Institute for Laser Technology ILT.
This project extended the process limits of laser polymer welding with high-brilliance beam sources. It started in October 2010 with 18 partners from 9 countries with an aim to develop high power, high brilliance lasers with new wavelengths between 1500 and 1900 nm that are adapted to the absorption properties of polymers.