Dangers during resistance welding

Resistance pressure welding and the equipment required for it are among the joining technologies that are highly controllable in terms of safety. Numerous DVS leaflets and ISO standards have been developed over the last few years and contribute to the high level of safety. Nevertheless, hazards can arise when using the various methods of resistance pressure welding. Primarily, these are hazards due to the electric current, mechanical processes, burns (from welding spatter), noise and emissions.

All resistance pressure welding processes work with low voltages below the maximum permissible contact voltage and the process-related high currents. Due to the low voltage (safety extra-low voltage of less than 42 volts), direct contact with the parts carrying the welding current and the workpieces during welding is basically not dangerous. In the direct vicinity of resistance welding equipment, strong magnetic fields also occur during welding due to the high welding currents.

Workplaces at resistance welding equipment must be marked with the prohibition sign “Prohibition for persons with pacemakers” and the warning signs “Warning of magnetic field”. Especially in the case of the very widespread medium-frequency welding systems, a voltage that is dangerous to touch is still contained in the so-called intermediate circuit of the inverter after the power source (inverter) has been disconnected from the mains. Depending on the type and design, the discharging time can be up to several minutes.

This should also be taken into account. The units are equipped with appropriate warnings. More safety instructions can be found in the operating instructions of the machines, devices and systems as well as in the ISO, DVS, DKE and VDE information.