Influence of the welding parameters on the structure and mechanical properties of vibration welded joints of dissimilar grades of nylons

Because of very attractive mechanical properties, nylons make interesting group of materials, used in many engineering applications. Vibration welding is a welding method used to join various kinds of thermoplastics. Almost 15% of all welds of thermoplastics are made with the use of vibration welding. The ability of vibration welding of different kind of polymers may present cost advantage over the other welding techniques and may allow to produce elements of lower weight and of a high quality. This work presents results of vibration welding of dissimilar materials joints made of nylon 66 (PA66) and 30% glass fibres nylon 66 (PA66 GF30). The aim of the studies was to determine the influence of the welding conditions on the quality of vibration welded joints. The quality assessment was done on the base of tensile tests and microscopy examination, conducted on light microscopy and scanning electron microscopy (SEM). Results of the tensile test indicate that it is possible to achieve good quality of joints at the proper welding conditions. The light microscopy examination showed that the welding parameters influence the orientation of the glass fibres in the weld zone, on the continuity of the material in the weld and on the thickness of the weld. The results of the SEM indicate that the vibration welded joint is formed as a result of joining of the matrixes of two welded nylons.