Patent ID: 11951289
Assignee: WEST PHARMACEUTICAL SERVICES, INC.
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 8:
9. A syringe comprising a barrel and a piston within the barrel, the piston manufactured by a method comprising:
placing a first rubber sheet and an inert film between die plates of a first forming tool;
vulcanizing the first rubber sheet and the inert film between the die plates of the first forming tool to form a first piston body, the first piston body comprising a cylindrical portion, a central face portion at a distal axial end of the first piston body, and an annular curved portion, the central face portion and at least a part of the annular curved portion being enclosed by the inert film;
blanking out the first piston body from the first rubber sheet and the inert film;
placing the first piston body into a second forming tool;
placing a second rubber sheet into the second forming tool;
vulcanizing the second rubber sheet and the first piston body together to form a second piston body and joining the second piston body to the first piston body to form the piston, the second piston body comprising a proximal axial end that circumscribes the second piston body; and
blanking out the piston from the second rubber sheet at a trim edge, wherein:
the trim edge is spaced apart from the inert film between the inert film and the proximal axial end,
the cylindrical portion and the part of the annular curved portion maintain a fluid-tight seal with an inner wall of the barrel, and
an outer boundary of the inert film is configured to be proximate to a leading-distal edge of the fluid-tight seal to minimize contact between the inert film and the inner wall of the barrel.