Difference Between Spot Welding and Tack Welding

Welding is a very important part of construction industry along with fabrication, maintenance and repair of structures and metallic parts. Though there are other methods of joining metals together, welding is the easiest and fastest method. Welding is a term that refers to the process of heating metals and making them flow together to join easily. A lot depends upon the efficiency of the welding process as not only structures but also the safety of people hinges upon welding. This is why a welder in industrial applications needs to be of the highest order. There are many techniques of welding and we shall talk about spot welding and tack welding along with their differences in this article.

Spot Welding

It is also known as resistance spot welding because of the application of heat and pressure to secure two or more metal parts together. The metals being joined together show resistance to the passage of high electric current that is used and heat is generated in the metals held under high pressure. Spot welding is used to sheet materials using copper alloy electrodes for the application of pressure and electric current. Because of heat and electric current the surface of the metals being joined melt, creating a molten pool. This molten metal is contained in its place by the application of high pressure through electrode tip and the surrounding metal.

Spot welding is one of the oldest welding techniques and can be used on thin foils as well as thick sections but avoided for sheets having a thickness of more than 6mm. All over the world, spot welding is widely used in many industrial applications, particularly assembly of automobiles and other vehicles.

Tack welding

Tack welding is a preliminary part of many welding techniques. It is a type of temporary weld and ensures that the parts to be welded together are secured in their places. This helps in avoiding any defects arising after welding has finally been completed. The main purpose of tack welding is to align and secure the parts to be weld till final welding is done. It helps in saving a lot of time and effort as otherwise much time would be required in assembly of parts. Several tack welds at short distance ensure that parts to be weld finally are secured in their place. One advantage of this process is that if any defect is detected before the final welding procedure, tack welds can be easily removed and parts can be reassembled and realigned and tack welded again.

It is improper to think of tack welding as unimportant as it is a pre welding procedure but often it turns out to be as important as final welding saving much time and material.

Difference Between Spot Welding and Tack Welding

• Tack welding is a preliminary process in any welding project

• Tack welding takes place before spot welding

• While tack welding ensures that parts to be welded finally through spot welding are held securely and properly aligned, spot welding finally joins the parts together