an apparatus and method for the manufacture of plastic couplings for joining together two lengths of plastic pipe . the couplings are manufactured from blanks of plastic material , such as polyvinyl chloride , which are heated to the thermoplastic state . the blanks are expanded between two mandrels which come together inside the ends of the blank . the mandrels have an outer member with a thin walled section and a nosepiece inside of that section which collapses at the end of the inward stroke of the mandrels so that the center shoulder of the coupling is not as wide as that of the prior art coupling . this results in a coupling which is shorter and lighter than the prior art coupling and yet is the full equivalent of the prior art coupling .