Selection of Processing Methods and Parameters for Composite Inserts in Window Profiles with Regard to the Strength of Their Welds

In the study of structural materials, the analysis of fracture and deformation resistance plays an important role, particularly in materials widely used in the construction industry, such as poly(vinyl chloride) (PVC). PVC is a popular material used, among others, in the manufacture of window profiles, doors, pipes, and many other structural components. The aim of this research was to define the influence of the degree of milling of the glass-fibre-reinforced composite on the strength of the window frame welds, and in the next step, to propose new welding parameters to obtain sufficient strength properties that allow reducing the cost of the technological welding operation. During the tests, it was found that the average failure load of the composite samples was highest at a milling depth of 1 mm and lowest at 6 mm. Up to a depth of 1 mm, the values of destructive loads show an increasing trend, while above this depth, a decreasing trend. A clear reduction in strength was observed when milling to a depth of 1.5 mm, which is related to material discontinuity and the lack of a visible weld joint caused by milling too deep. The differences in average failure loads between the samples of 0 mm, 0.5 mm, and 1 mm milling are minimal.