Welding of thermoplastics reinforced with random glass mat

Abstract

Thermoplastics reinforced with random glass mat have high strength and stiffness; the fibers dominate the mechanical behavior of these composites. The results of this investigation have shown that fibers are ineffective for reinforcing hot‐tool and vibration welded butt welds. The maximum weld strengths attained with GMT are comparable to the strengths of good welds of the unfilled material. The optimum hot‐tool welding parameters for the reinforced materials are different from those for the unfilled material. Unfilled polypropylene is easier to weld than unfilled polyamide. This characteristic is also true of the reinforced materials. In vibration welding, high welding pressures and high amplitudes result in lower mechanical properties. The optimum penetration depends on the fiber content of the bulk material. This penetration dependence is different from that for unfilled thermoplastic, for which the mechanical properties are independent of the penetration once a steady state has been attained.

Fusion Bonding/Welding of Thermoplastic Composites

“…It should be noted that the welding penetration has a direct relationship with welding pressure. The influence of welding penetration on the mechanical performance of the weld can also be explained through a typical stress-strain curve for a hot-tool welded specimen (see Figure 17) [13]. Samples with low welding penetration have high strength because the fibers remain mainly in the direction of the load path.…”

“…Figure 15 shows a schematic of the hottool welding. Figure 16 shows the variation of pressure with time during the welding process [13]. The surfaces to be joined are heated to the melting temperature by direct contact with the heated tool under application of pressure.…”

“…Several researchers have shown that vibration-welded joints have better mechanical performance than adhesive bonded or riveted joints [7,13]. Several parameters affect the welding process, including material properties, weld type, vibration frequency and amplitude, welding pressure, and welding time.…”

“…Also, it has been employed to weld thermoplastic composite parts [11][12][13]. In linear vibration welding, the two parts to be joined are brought into contact under pressure.…”

The effect of the welding parameters and the coupling agent on the welding of composites

“…The results that depend on heating time have provided a comparison for a variety of filler-reinforced PP composites. M. Gehde et al 14 have investigated the effect of melting length and joining length for different heating times (0 s, 60 s and 120 s) on the material reinforced PP with a random glass mat (PP-GM). PP-GM attains the highest strength at a low joining length.…”