Resistance welding a porous metal layer to a metal substrate
AssigneeZimmer, Inc.
InventorsJoseph R. Vargas, Steven Seelman, Clarence M. Panchison
Life of this patent
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Abstract
An apparatus and method are provided for manufacturing an orthopedic prosthesis by resistance welding a porous metal layer of the orthopedic prosthesis onto an underlying metal substrate of the orthopedic prosthesis. The resistance welding process involves directing an electrical current through the porous layer and the substrate, which dissipates as heat to cause softening and/or melting of the materials, especially along the interface between the porous layer and the substrate. The softened and/or melted materials undergo metallurgical bonding at points of contact between the porous layer and the substrate to fixedly secure the porous layer onto the substrate.
Claims21
A method of manufacturing an orthopedic prosthesis comprising the steps of:
- providing a metal substrate;
- providing a previously-manufactured porous metal layer having a manufactured thickness, the previously-manufactured porous metal layer having a porosity of 55% to 90%;
- positioning the previously-manufactured porous metal layer against the metal substrate to form an interface between the previously-manufactured porous metal layer and the metal substrate, wherein said positioning generates a net contact area of 15% to 25% between the previously-manufactured porous metal layer and the metal substrate at said interface;
- applying a weld pressure holding the previously-manufactured porous metal layer against the metal substrate, wherein said weld pressure is at least 100 psi (0.7 MPa) but less than 3,000 psi (20.7 MPa), and wherein said net contact area is maintained despite applying said weld pressure;
- and
- directing an electrical current to the interface between the previously-manufactured porous metal layer and the metal substrate to resistance weld the previously-manufactured porous metal layer to the metal substrate while maintaining the manufactured thickness of the previously-manufactured porous metal layer.
A method of manufacturing an orthopedic prosthesis having a metal substrate and a previously-manufactured porous metal layer, the method comprising the steps of:
- positioning the previously-manufactured porous metal layer against the metal substrate to form an interface between the previously-manufactured porous metal layer and the metal substrate;
- holding the previously-manufactured porous metal layer against the metal substrate with a weld pressure of at least 100 psi (0.7 MPa) but not exceeding a compressive yield strength of the previously-manufactured porous metal layer;
- and
- directing a pulsed electrical current to the interface between the previously-manufactured porous metal layer and the metal substrate to resistance weld the previously-manufactured porous metal layer to the metal substrate, the pulsed electrical current including at least a first pulse and a second pulse separated from the first pulse by a cooling time,
- wherein said positioning step generates a net contact area of 15% to 25% between the previously-manufactured porous metal layer and the metal substrate at said interface, and wherein said net contact area is maintained during said holding and directing steps.
A method of manufacturing an orthopedic prosthesis comprising the steps of:
- providing a metal substrate;
- providing a previously-manufactured porous metal layer having a net surface, the net surface of the previously-manufactured porous metal layer being formed by:
- providing a porous structure having an outer surface;
- coating the outer surface of the porous structure with metal to produce the porous metal layer;
- and
- after the coating step, maintaining the outer surface without machining the outer surface to arrive at the net surface;
- positioning the net surface of the previously-manufactured porous metal layer against the metal substrate to form an interface between the previously-manufactured porous metal layer and the metal substrate, wherein said positioning generates a net contact area of 15% to 25% between the previously-manufactured porous metal layer and the metal substrate at said interface;
- holding the previously-manufactured porous metal layer against the metal substrate with a weld pressure of at least 100 psi but not exceeding a compressive yield strength of the previously-manufactured porous metal layer;
- and
- directing an electrical current to the interface between the porous metal layer and the metal substrate to resistance weld the previously-manufactured porous metal layer to the metal substrate, wherein said net contact area is maintained during the directing step.
A method of manufacturing an orthopedic prosthesis comprising the steps of:
- providing a metal substrate;
- providing a previously-manufactured porous metal layer having a manufactured thickness, wherein the previously-manufactured porous metal layer includes a porous structure in the form of a layer that has an outer surface coated with a metal coating forming an outer coated surface;
- positioning the previously-manufactured porous metal layer against the metal substrate so that said outer coated surface contacts the metal substrate at an interface, wherein said positioning generates a net contact area of 15% to 25% between the previously-manufactured porous metal layer and the metal substrate at said interface, and wherein said positioning step maintains said manufactured thickness yet includes applying a weld pressure of at least 100psi (0.7 MPa) holding the previously-manufactured porous metal layer against the metal substrate;
- and
- directing an electrical current to the interface to resistance weld the previously-manufactured porous metal layer to the metal substrate.
Dependencies are inferred from the claim text.