Resistance welding

The resistance welding process

Resistance welding is a widely used technology in the sheet metal fabrication, and has been for a long time. The experts at Minifaber, which has been involved in cold sheet metal fabrication for years, including resistance welding, will explain it all to you.

Resistance welding involves melting and joining two metal parts by means of the heat generated when an electric current flows through them. Exploiting the Joule effect, the heat required for fusion is generated precisely at the point where the current flows. This point is where the two metals to be welded are closed between two welding electrodes, which are pushed together by a closing force.

What will we explore on this page?

What to consider before welding

The types of resistance welding

Minifaber's fleet of machines

The advantages of welding in Minifaber

The parameters to be considered in resistance welding

Resistance welding is performed by means of a high-intensity current, which causes the metals to melt as it flows through them in a very short time. This is precisely why it is necessary to know the material to be welded, its physical properties and the shape of the parts in contact. Another important aspect to be taken into account is the force of the electrodes, which must act as the current flows.

So the main process variables are:

• The type of material to be welded

• The welding current

• The welding time, which should be minimal but adjustable

• The pushing force of the electrodes

• The shape and profile of the contact surfaces to be welded.

What electrodes for resistance welding?

In resistance welding, the heat required to bring the material to fusion is generated by a current flowing through two electrodes connected to a transformer. These are copper alloy electrodes that must withstand high currents and temperatures, mechanical forces and high productivity. 

Electrodes can be made in different shapes, rounded or tapered tip to better suit the geometries of the parts to be welded. 
They should always be cooled so that they do not wear out quickly and to prevent the welding parameters from changing.

The types of resistance welding

Resistance welding is usually used to weld thin sheets (usually less than 2 mm thick). Materials that can be welded by this process include ferrous materials, electro-galvanized materials, stainless steel and aluminum. By taking certain precautions, it is also possible to weld materials as different as stainless steel and a ferrous material.

There are different types of resistance welding:

• Spot welding: the metal sheets to be welded rest on each other, with flat contact surfaces

• Projection welding: projections (bosses or other types of projection on the sheet metal) facilitate controlled current flow to optimize the joint weld between the two parts to be welded

• Butt welding: the parts to be welded are held in two clamps and pressed against each so that the contact surfaces weld

• Roll welding: the parts to be welded are pressed by two rollers rotating on the sheet metal to create continuous welds.

Resistance welding is widespread in a variety of industries: from automotive, home appliance, gas distribution and more. 

Focus: resistance welding in the gas distribution sector

A special and very advantageous application is welding turned and threaded bushings on sheet metal parts that were previously cold stamped. This makes continuous welds quickly without using consumables.

Minifaber's fleet of resistance welding machines

Minifaber has a fleet of state-of-the-art machines to perform resistance welding, ensuring precise and flexible solutions. We have developed a new series of machines designed specifically for this type of welding. They offer a wide variety of assembly combinations and feature electronic control. The latter is an essential element of the resistance welding process because it provides a perfect combination of performance and control for each welding application.

Resistance welding with Minifaber

Minifaber has several flexible and very practical resistance welding machines called spot welders. These can be arm-mounted, hanging, fixed on the bench.

In addition, Minifaber makes special production machines dedicated to the customer's specific project, with solutions for high productivity and power (up to 120,000 Amps).

Minifaber provides a resistance welding service that is performed in-house from start to finish: we are available to work on both small and large quantities, to make semi-finished products or complex finished products. A special Minifaber service: adding resistance welding machines to assembly lines specifically for a customer’s special product. 

With more than 65 years of know-how in sheet metal welding, continuous investment in technology and a customer-oriented approach, we are now able to manufacture complex parts for international companies.