Joining of plastics
Joining of plastics – interactive engineering module focused on plastic welding. Learning format: Interactive visualisation · Active learning. Explains the principle, technical relationships and practical use.
Topic overview
Plastic welding is primarily applicable to thermoplastics , which soften or melt when heated and solidify again on cooling. Thermosets, thermoset-matrix composites and highly cross-linked materials are not normally fusion welded; they are joined by adhesive bonding, mechanical fastening or special processes.
Joint quality depends on material compatibility, cleanliness, moisture, surface oxidation, pressure during joining, heating time, tool temperature, stable cooling and prevention of polymer degradation.
PE, PP, PVC-U/PVC-C, PVDF, ABS, PA, PC, PMMA and other thermoplastics can be fusion joined when they are compatible and the surface is uncontaminated.
Amorphous plastics soften around the glass-transition temperature; semi-crystalline plastics have a more distinct melting temperature. Their process windows, cooling behaviour and shrinkage differ.
What the module covers
- Plastics are not joined like metals: polymer softening, chain diffusion and controlled cooling determine the result.
- Material logic: what the welding engineer must know before selecting a process
- Weldable materials
- Amorphous versus semi-crystalline
- Overheating is not preheating
- Drying and cleanliness
- Overview of plastic-joining methods
- Typical heated-tool butt-welding cycle for PE
Related engineering terms
The module connects these terms with practical engineering explanations:
Continue with the practical module.
Open this topic directly in the interactive WeldScope portal.