Fast and energy efficient hot gas welding of plastics: New process patented by BASF
Last update on May 27, 2026
Hot gas welding of high-performance thermoplastics – particularly polyphthalamides – presents persistent processing challenges: long heating times, high gas temperatures, narrow nozzle-to-rib tolerances, and the risk of nozzle clogging by molten material.
BASF has patented a novel hot gas welding process designed to address these constraints simultaneously, enabling thermoplastic components made of Ultramid® Advanced PPA to be welded faster, more energy-efficiently, and in a more material-friendly manner than with conventional hot gas welding processes.
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A channel-based tool design for even gas distribution
At the heart of the patented solution is a modified tool architecture. Rather than directing hot process gas onto welding ribs selectively from individual nozzles, the process guides gas along the welding ribs via channel-like structures. This ensures even gas distribution and minimizes heat losses, plasticizing the welding ribs more homogeneously without requiring high gas temperatures or very small nozzle distances.
"Tests on PPA specimens have shown that the patented process can produce durable welded joints after very short heating times of around ten seconds," says Stefan Mochev, team leader Materials & Parts Testing. "By comparison, with conventional hot gas welding technologies, it is often not possible to achieve any joint at all within these short times. At the same time, high weld seam strengths are achieved, making the technology particularly attractive for function-integrated components with high mechanical requirements."
The process also produces a greater melt layer thickness within short heating times, providing additional leeway to compensate for component warpage – an important consideration for large-format or geometrically complex components.
Lower process temperatures and reduced nozzle clogging
The patented process allows lower process temperatures, reducing consumption of both energy and inert gas. The larger permissible distance between gas nozzles and welding ribs virtually eliminates the risk of individual nozzles becoming clogged by molten material – a recurring reliability and maintenance issue in conventional hot gas welding setups. According to BASF, this increases process reliability and reduces maintenance effort.
Polyphthalamides are identified as key materials for eMobility and fuel cell system applications due to their high thermal, chemical, and hydrolytic resistance. The patented hot gas welding process expands the processing options available for this material class, supporting more efficient component joining and further functional integration in these application contexts.