B29C 65/3456

Joining {or sealing} of preformed parts {, e.g. welding of plastics materials}; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" {characterised by the type of heated elements which remain in the joint being a layer of a multilayer part to be joined, e.g. for joining plastic-metal laminates}