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Stud welding versus resistance welding – Which is best for your project?

When designing in a weld fastener for your project there are several different weld fastener processes from which to choose. Two common choices for weld fasteners are resistance weld and stud weld fasteners. For your project, it’s important to know that not all welding processes are alike. Two common choices for weld fasteners are resistance weld and stud weld fasteners. Most often, design constraints, time, money and the finished look you want for your piece will determine which fastening process is best for your particular project.

Resistance weld fasters versus stud weld fasteners

These are two of the most common welding techniques, and they are two very different processes:

Heat: No Arc versus Arc

In resistance welding, both the fastener and the base material are heated by the flow of electricity through a resistive junction (two piece of metal contacting each other). They are each heated to a point where they are soft enough to melt together.

With stud welding, the heat is generated by an electric arc over an air gap between the stud and the workpiece. The tip of the stud is melted along with a localized spot on the workpiece. When the heating is complete the stud is plunged into the puddle on the work piece. This all happens in less than one second. When the stud plunges into the molten puddle there is molten material displaced. This displaced material is captured by a ceramic shield (ferrule) and forms a ring of expelled material around the fastener. This resultant ring must be accommodated by designers.

Pressure versus no pressure

In resistance welding as the parts are being heated, hundreds of pounds of pressure is being applied to push the fastener into the work piece. These means that the resistance welding equipment must have accesses to both sides of the work piece or that the work piece must be backed up somehow. This prevents resistance welding from being done with portable equipment. Most often, this means resistance welding must occur within a designated shop area where the equipment is located and can reach both sides of the work. Typically this pressure is applied to the work piece and a flange on the resistance weld fastener. There doesn’t HAVE to be a flange on the resistance weld fastener, but most often there is a flange for the equipment to apply pressure. Designers must allow for this flange in their projects.

Stud welding, on the other hand, requires no pressure. After loading the stud into the gun and initiating the arc, the gun applies the stud onto the base material.

The force supplied by the gun provides all the pressure needed to achieve a proper weld. Stud welding, therefore, can be accomplished with access to only one side of the work piece.

Weld Quality

Both process produce high quality welds. However, resistance welding typically melts several (3-4) small projections into the base material. Stud welding melts the full cross sectional area of a weld. There is more welded surface area in a stud weld when compared to the same size resistance weld fastener.

If you’re like other industrial users, you will appreciate the portability of the stud welding equipment, the speed of completion for each weld (less than one second), and the full cross sectional weld area. It makes stud welding a flexible and convenient welding choice.