Laser welding has for years been a good way to join parts made from the same or very similar polymers. Material options for the technique continue to expand.
DuPont Engineering Polymers, Wilmington Del. (www.plastics.dupont.com), for example, offers a wide range of suitable materials for laser welding.
It's relatively easy to produce strong welds with Delrin acetal, Zytel nylon (PA66, PA6, and PA12), and Zytel HTN (high-performance polyamide). Other weldable polymers attain strong welds but have limited processing latitude with respect to wall thickness and certain part configurations. Polymers in this category include Vespel TP, Crastin PBT (polybutylene terephthalate), Rynite PET (polyethylene terephthalate) thermoplastic polyesters, and Hytrel thermoplastic polyester elastomers, Special grades of Crastin PBT and Rynite PET with enhanced laser transparency provide the greatest process latitude in part thickness and welding conditions.
Most natural (uncolored) grades are sufficiently transparent to laser light to produce strong welds. There are also colored options that, though opaque to the naked eye, have enough laser transparency for successful welding. Standard black and some colored grades are suitable for laser-absorbent components of welded assemblies.
Key capabilities of laser welding
Automotive door lock covers are made from natural, laser-transparent Zytel PA66 welded to black, laser-absorbing Zytel PA66 housings
How laser welding works
Laser welding joins parts made from the same or very similar polymers. One part must absorb laser light and the other must be at least partially laser-transparent.
The laser beam passes through the laser-transparent part to reach the laser-absorbing component. Absorption of the laser energy melts the material in a localized area. Adjacent surfaces of the laser-transparent part melt via heat conduction. The molten surfaces cool and bond together when the laser beam removes or relocates.