Resistance welding a porous metal layer to a metal substrate

An apparatus for manufacturing an orthopedic prosthesis having a metal substrate and a porous metal layer formed of a plurality of ligaments defining open spaces therebetween, the apparatus comprising:

• a housing defining a chamber with a controlled atmosphere, the chamber sized to receive the orthopedic prosthesis;
• a controller;
• a power source;
• and
• a weld head configured to be in electrical communication with the power source, the weld head comprising:
• an electrode mounted to the weld head and configured to establish electrical communication between the weld head and the orthopedic prosthesis via direct contact with the orthopedic prosthesis at an interface such that during a manufacturing process, the controller directs a pulsed electrical current from the power source to the orthopedic prosthesis to bond the porous metal layer to the metal substrate;
• wherein the electrode comprises an initial contact surface that has a microarchitecture comprising a plurality of projections that are shaped to approximate a surface texture formed by the plurality of ligaments and open spaces of the porous metal layer at the interface before bonding occurs;
• and
• wherein the weld head is configured to move the electrode into and out of contact with the orthopedic prosthesis such that the electrode can be reused in multiple bonding processes.