When projection welding, the component parts must be specifically manufactured with dimples or projections, in order to ensure that they fit together and maximize contact between the parts. The welding process is tailored to the material and component’s intended use.

The welder applies force and electrical current through the welding machine at one point of contact. The pressure, current strength, and amount of time that the current is applied will vary depending on the material and processing specifications.

Projection welding offers a wide range of benefits over more traditional welding methods, including:

• Increased production. The process allows for more than one weld to be completed at one time, thereby increasing production output.
• Extended lifetime. Projection welds have a longer life expectancy than spot welds, as it requires less heat and pressure during the welding process.
• Versatility. Projection welding equipment is easy to adjust to different parameters, so it can be used for a wide variety of parts and components.
• Ease of use. Projection welding uses highly automated equipment and multiple welds can be handled at one time.
• Clean finish. The point of contact is on one side and the pressure is minimized, so projection welding allows for reduced surface imperfections at the welded joint and results in a smoother finish.
• Closer welds. Projection welding equipment allows for welds that are closer spaced, because there is less pressure applied to each joint.

Spot welding and projection welding have some similarities, but they are typically used in different situations.

• Spot welding is the most common form of welding and differs from projection welding in a number of ways. This process is typically used to connect large components or sheets of metal using metal currents along the joint. The current is directed at one point—as opposed to the multiple projections found with projection welding—and requires more current and pressure. Spot welding is particularly useful for corners and thin materials.
• Projection welding is more useful for thick metal materials and products that require an exceptionally strong weld, since less heat and pressure during the welding process yield a stronger joint. Projection welds are also less visible than spot welds, allowing for a more aesthetically pleasing finished appearance. Projection welds can also used to weld a nut, stud, or projection on steel and is used in many automotive assemblies.