Resistance Welding

While AMADA WELD TECH did not invent resistance welding, it perfected the technology and was the first to apply it to welding small microelectronic modules in the early 1950’s. Today, AMADA WELD TECH offers a wide range of welding technologies which have been used successfully for decades. Core technologies include Linear DC, High Frequency Inverter, Capacitive Discharge and AC. They are used for spot welding, seam welding, gap welding, projection welding, thermo compression bonding, strand welding and insulated wire welding. Four key parameters influence the quality of resistance welding and need to be closely monitored to achieve best in class results: materials, energy, weld force and time.

Materials

The physical metallurgy of the materials to be welded determines the application of the process variables. In general there are two categories of metals to be welded: “Conductive” (such as aluminum, copper, silver and gold), and “Resistive” (steel, nickel, Inconel, titanium, tungsten, molybdenum) with a third, small, middle ground category occupied primarily by brass. In general, electrically conductive materials are also more thermally conductive and are softer. To determine whether your materials are suitable for resistance welding, please refer to our Material Weldability App.

Force

A key parameter of all three types of resistance welding is weld pressure or force. The proper and consistent application of force improves the mating of the materials increasing the current paths, reducing the interface resistance, and insuring that any oxide barriers between the workpieces are broken through. Repeatable force control insures repeatable weld quality through consistent electrical contact resistance and consistent heat balance. Force control can also be used to trigger welding energy when a pre-determined force level has been achieved, often called “force firing.” Optimum welds are achieved when the applied force is precise, repeatable, controlled by time schedule, used to fire the power supply, and regulated both to reduce the initial impact and not to become excessive after the weld.

Energy & Time

Energy is supplied by a welder with either an internal or external transformer which both powers and controls the application of heat and time in the resistance welding process. In general terms, resistance welding applies high current with low voltage; in a little more detail, the welding power supply transforms, modulates and controls the electrical energy of the power line and applies it to the weld according to a user defined or user programmed “weld schedule.” Depending on the complexity and intricacy of the power supply the user can program from one to more than 100 attributes and permutations of the welding process, and, using a microprocessor, store these attributes as a uniquely defined “weld schedule.” AMADA WELD TECH offers a full range of resistance spot welders with 5 – 200,000 A output power including high frequency inverter, linear DC, capacitive discharge and AC technologies capable of addressing both small and large welding applications.