To ensure high-quality joints of polyurethane foam with hot air, it is necessary to determine the optimal welding parameters. We welded foams of different densities with different temperatures and nozzle dimensions. The welding speed and the distance between the nozzle and the foam were constant throughout the process. An insufficient amount of energy input results in not enough welded material and lower joint strength. Excessive energy input can lead to excessive remelting of the material, lower joint strength, because of a smaller cross-section, and a harder weld to the touch. We performed a test hot air welding within predefined process parameters. We evaluated the welds according to three criteria: visual evaluation of the welded joint, a break point in the tensile-shear test (at the joint or in the base material), and the hardness of the weld to the touch. We found that the density of the foam strongly influences the selection of process parameters. In our case, we determined that the most suitable nozzle was the 20 mm x 2,5 mm dimension nozzle, and optimal welding power of hot air gun at level 3,5.
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