The short- and long-term properties of welded high-temperature-resistant thermoplastics

Abstract

AbstractHigh-performance plastics, such as polyphenylene sulfide or polyphthalamide, are increasingly being used in highly stressed areas, primarily due to their outstanding thermal and mechanical properties. Due to the increasing demands on plastic components in terms of geometry, functional integration, etc., components produced by primary molding often have to be welded in an additional process step. Furthermore, there are often restrictions with regard to component cleanliness, which is why converting, non-contact welding processes are of great industrial interest. However, as a result of the changeover-step in these processes, the previously plasticized areas cool down. For materials with high melt temperatures this circumstance can lead to inadequate weld seam qualities.The aim of the investigations was therefore to expand the understanding of the process of welding high-temperature-resistant plastics, to identify optimum welding parameters and to determine the mechanical short- and long-term properties of the welds. Furthermore, a comparison was made between the changeover welding processes and single-stage vibration welding in order to clarify the relevance of short changeover times.It could be shown that a significant correlation exists between the changeover time, the melting temperature and the resulting weld strength. Furthermore, the selection of the welding process and thus the type of heat input seems to have an influence on the long-term properties of the welds at high test temperatures.