Mon, 09 September, 2024
TWI addressed the challenge of laser welding difficult-to-weld polymers through thermal management and control of interface temperatures. Polybutylene terephthalate (PBT), polyphenylene sulphide (PPS) and thermoplastic elastomers (TPE) are all considered to be difficult to weld, despite their widespread use across a range of industries.
Our recent ‘Poly-Smart’ project investigated transmission laser welding of PBT, PPS and TPE polymers, including interface temperature monitoring using a Hamamatsu LD-Heater laser, which is being used at TWI Cambridge.
Figure 1. Overhead view of PBT coupon held under pressure, underneath laser welding head
The LD heater is a spot heating light source incorporating real-time temperature monitoring that allowed us to develop a welding procedure specification for transmission laser welding of PBT, PPS and TPE following the production of demonstration coupon samples of the materials.
This exploratory project successfully produced welds in all three materials with associated temperature monitoring data, creating demonstration samples in lap weld configurations.
Figure 2. Welded PBT demonstrator sample
Figure 3. Welded PBT demonstrator sample
The use of the real-time temperature monitoring data ensured that there was fine temperature control during the welding process along with the identification of any potential welding defects. The project also delivered demonstrable benefits in terms of productivity, reduction in reject rates and cost/time savings over other joining methods such as ultrasonic, hot plate or adhesives.
Potential applications for this project include:
- Aerospace - EVTOL/UAM systems using PBT and TPE
- Medical - medical devices – TPE
- Electronics - PBT, PPS packaging systems
- Automotive - chemical/leak proof packaging (PBT, PPS, TPE)