Tack welding is a specific process in which you apply a small dot-like bead along the joint length before the final weld is completed. The amount of dots or tacks needed will change based on the material thickness, metal type, geometry of the joints and the length of the weld. 

Tack welding is an important skill for any welder and should be learned as one of the fundamental skills in welding. Tack welds are used in nearly every welding project and are very important in welds with complex joints. 

The Purpose of the Tack Weld

The tack weld is designed to create a proper alignment that is held in place for when the actual weld is performed. While the tack weld is not part of the main weld it still needs to be done properly and when done improperly can cause lots of issues. Tack welds allow the joint to be held in place without the use of clamps but clamps and magnets may be used for some projects. Tack welds can hold up to the stress created by welding keeping the joints and metal in alignment. Tack welds don’t restrict access the way clamps do allowing a welder to access all points without restriction. The internal stresses of welding like metal expansion and contraction can cause the joint to warp and separate but the tack welds keep it in place. 

Size and Amount of Tack Welds

Tack welds have to stay small so they can be incorporated into the final weld but still be large enough to hold the panels together properly. The balance can be challenging but tack welds should never be larger than the final weld. An example of this is if the weld joint is going to be ½-inch wide you should keep your tack welds to 5/8-inch wide or smaller. If the tack welds are too large the weld shape can be affected and cause a stress point 

When choosing the size and amount of tack welds there are a lot of factors to consider. First consider internal stresses. The larger the final weld the more stresses the tack weld will be subjected to. Next the length of the joint should be considered, longer joints need more tack welds. The complexity of the joint is also important and a short complex weld may need more tack welds than a long simple joint. The material thickness is also something to be considered, thinner material often needs more welds. The position of tack welds is as important as the amount and size. 

Depending on the type of weld being performed tack welds are performed differently. Tig welding, stick welding, and MIG or FCAW welds all have specific methods for creating a tack weld. 

There are a few different methods of applying a tack weld. The standard tack weld is placed on the joint and will be conceded by the final weld. This is designed to hold the pieces together so the final weld can be performed. The Bridge tack weld is used on joints that need a root opening like a pipe. This tack weld bridges the gap. This method requires more skills than the standard tack weld. Finally the hot tack weld is used to close a significant gap. The tack is excessively heated and then hammered into place. The high heat can help to create a contraction bringing the parts together. 

When done properly tack welding is a great method for joining materials before the final weld. A tack weld is a vital part of any welder’s skill set and can be a great method for joining materials prior to the final weld. Jacks metal works can help with welding projects of any size. We are happy to work with you on your welding project no matter how big or small. Our team is highly skilled and can perform welds ranging from basic to highly technical.