Publisher Summary This chapter provides information on the utilization and suitability of ultrasonic welding, vibration welding and thermal impulse welding for joining Grilamid TR55, TR55UV, TR55LX, TR55LY and TR55FC parts. When welding, the surfaces to be joined need only be melted and rapidly pressed together. Standard welding machines are used for ultrasonic welding. The horn design should be according to the established recommendations. Injection molded parts of Grilamid TR55, TR55UV, TR55LX, TR55LY and TR55FC can be welded by high frequency as well as low frequency. It is also possible to insert metal parts ultrasonically. Parts which are not being welded within a few hours of molding should be stored in moisture proof packaging to insure adhesion when assembled later.