After trimming, additional features are added by die cutting, routing, CNC milling, hot-gas welding, or chemical bonding to produce the final part.
Hot-gas welding is used to add drains, structural supports, mounting supports, or lifting features.
Chemical bonding is used when heat from hot-gas welding would deform or damage the part, or the material used in the part is not suitable for welding.
Hot-gas welding is as well the most widespread method of unit repair in plumbing, marine an automotive body works, leading to a considerable saving for the customer and also decreasing waste by increasing the lifespan of the units.
To ensure reproducibility of the welding parameters (temperature, pressure, velocity, and gas flow), double-V welded joints were prepared using a computer-controlled hot-gas welding device, described elsewhere [10, 11].
Engel worked with German moldmaker Hummel-Formen, which applied for a patent on in-mold hot-gas welding
, and German welding equipment supplier KVT Bielefeld.
Hot-gas welding is one of the external heating methods, as it uses hot gas to increase the surface temperature of the materials to be welded up to the softening point.
Based on the data found in the literature , the quality of the welded seam prepared by hot-gas welding is defined by three parameters (welding temperature, the force that squeezes the welding material into the seam groove, and the flow rate of hot gas).
The welding parameters of manual hot-gas welding became controllable through the automation of the welding process, i.e., the human factor was eliminated.
Thermodynamic Description of the Hot-Gas Welding Process
, in which surfaces of thermoplastics at the joint area are heated by a stream of hot gas and then the fused surfaces are pressed together to weld the thermoplastics .