Plastics joining extrusion

Conventional friction stir spot welding leaves behind a keyhole (exit hole) after the weld has been done. In order to avoid this, GKSS of Germany invented a process that would fill the keyhole (Ref 4). This method was called the refill FSSW process. The joined region consists of a spot of material that has been plasticized, displaced in a process similar to a back extrusion, and then replaced, forming a fully consolidated weld that is nominally flush with the original surface. 

Laminate la-m3- nat (1665) (1, n). A product made by bonding together two or more layers of material or materials. The term most usually applies to preformed layers joined by adhesives or by heat and pressure. However, some authors apply the term to composites of plastic films, with other films, foils, and papers, even though they have been made by spread coating or by extrusion coating. In the reinforced-plastics industry, the term refers mainly to superimposed layers of resin-impregnated or resin-coated fabrics or fibrous reinforcements that have been... 

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