Resistance welding is a form of spot welding commonly used to join two pieces of metal by the application of electricity. Like other types of spot welding — such as laser welding — resistance welding is often used in the manufacture of medical devices because it works well with thin materials.
The choice of which welding method to use depends on the materials to be welded, the location of the weld, and the mechanical strength desired. Electric resistance welding works through the simultaneous application of pressure and electricity to the areas to be joined. Copper electrodes press the two pieces of metal together and then initiate a low-voltage, high-current DC electrical flow. The higher resistance experienced at the meeting point of the two pieces raises the temperature, and the resultant heat causes the metals to bond. The electricity is then turned off and heat is dissipated by water-cooled copper electrodes, which strengthens the bond between the two pieces.
Three types of bonds can be created. Thermocompression bonds can be used to weld dissimilar materials. The process results in excellent shear and tensile strength but poor peel strength. A fusion bond results when the materials are briefly heated to their melting points, resulting in a fusion nugget with good shear, tensile, and peel strength. A reflow bond uses a blazing material to form a bond that has high tensile strength but poor shear and peel strength. Resistance welding is ideal for the manufacture of medical devices because the low-voltage results in little to no deformation of the materials to be joined and does not produce any contaminants. The low amount of electricity used makes it a cost-efficient process. At Proven Process, our manufacturing engineers are able to perform all three types of resistance welding to ensure the connection conforms to the unique needs of the project.