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Video: Polyamides And Polyesters For Welded Components
Lanxess has developed four polyamide 6 and two PBT compounds (polybutylene terephthalate) specifically for plastic parts that are welded. The new materials are aimed primarily at applications under the bonnet and are optimized for large-scale production. "They meet requirements such as higher engine compartment temperatures, higher internal pressures for hollow bodies and the trend towards smaller installation spaces," explains Frank Krause, an expert in joining technologies at Lanxess.
Higher weld strength
Durethan BKV 30 XWP, BKV 30 XWP HV and BKV 30 XWP XT were developed for heating element, infrared (IR) and vibration welding, and Durethan BKV 30 XWP LT for laser transmission welding. All four polyamide 6 types are reinforced with 30% glass fibers. The abbreviation XWP stands for "Xtreme Welding Performance".
Durethan BKV 30 XWP fulfills higher requirements in terms of process safety, weld strength and weld resistance when it comes to IR, vibration and heating element welding. Its flexural strength is somewhat higher than that of the standard polyamide 6 Durethan BKV 30 H2.0. Potential applications include air intake manifolds and modules.
An advantage of Durethan BKV 30 XWP HV (High Viscosity) is its higher melt toughness compared to BKV 30 XWP. This pays off particularly when vibrating and heating element welding, because the processing window of both processes widens. "The compound produces mechanically very strong welds," explains Krause. "For example, it improved the burst pressure resistance of air intake modules for two four-cylinder engines by over 16% in one module and almost 40% in the other compared to corresponding counterparts made from a standard polyamide 6 with 30% glass fibers."
Long-term stability up to 200 ° C
The heat-stabilized Durethan BKV 30 XWP XT (Xtreme Temperature) can be used at long-term use temperatures up to around 200 ° C. Krause explains: "As far as we know, high-performance polyamide is a rarity on the market with its high weld seam strength after aging - both at room temperature and in 'engine room-typical' heat." The melt viscosity is comparable to that of Durethan BKV 30 XWP HV. Possible applications include charge air and intake pipes as well as hollow bodies in the oil circuit.
Durethan BKV 30 XWP LT (Laser Transparency) has increased laser light transmission in the wavelength range that is common for laser transmission welding. "It ensures a high and fast heat input into the joining area, which benefits economic production," says Krause. The new polyamide is offered in a natural color and in a special black color. Possible applications are housings for oil, airbag and other sensors, housings that are welded to a cover, and hollow bodies with complex, mechanically sensitive internal geometries such as air collectors.
Hydrolysis stabilized and laser transparent
The Pocan B3235 LT and B3235 HR LT PBT compounds were also adapted for laser transmission welding. They are natural in color and available in black coloring that is laser-transparent for the near infrared. "Pocan B3235 HR LT is hydrolysis-stabilized and is particularly suitable for engine compartment components that have to be insensitive to heat and moisture," explains Joachim Morick, product developer for Pocan. "For example, we see good application opportunities for housing components for control devices such as electronic parking brakes that are joined together by laser welding." In comparison to Pocan B3233 HR, laser transmission in the wavelength range from 800 nanometers to 1200 nanometers, which is relevant for laser welding, is more than double so tall. For laser weldable PBT components,Pocan B3235 LT is the material of choice for those who are not exposed to high temperatures and moisture. It is almost twice as laser transparent as the standard PBT Pocan B3235. (kj)