vibratory welded connections are formed between first and second members of thermoplastic material by interposing a junction piece of similar material and vibrating the junction piece at high speed while pressing the first and second members in a controlled manner against opposite sides of the junction piece . friction created by the vibration generates heat which melts a small amount of material at the engaging surfaces which upon cooling provides a strong welded joint having minimal flash . entire frame systems such as window frames can be fabricated by an apparatus system which forms a friction welded joint between adjacent ends of the frame members . furthermore the frame can be fabricated around a panel such as a glazing panel . the welded connections formed by the system do not mar the finish of the frame members and produce no unsightly flash bead requiring subsequent machining steps for its removal .