What is Tack Welding? A Brief Guide

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Tack welds are small welded areas that are designed to clamp two base pieces of metal together until another process can be used to create a permanent connection. These are temporary welds designed to hold the base elements the right distance apart and in perfect alignment so your hands are free to work.

What is Tack Welding

Tack welds are more reliable than clamps because clamps can move and allow the materials to shifting and that can mess up the entire project. The tack weld holds the item perfectly in place and does not allow any movement.


The spacing of the tack welds

The tack welds are spaced specifically to make sure the base materials are held firmly at their most crucial points. Most of the time tack welds are done in a series that are spaced a specific distance from each other.

Tack welds are normally between ½” and ¾” in length. There is no standard set of rules for this size these are just the common lengths that you will find tack welds made in. The size of the welds and the distance between the welds depends on the material you are connecting and the thickness of that material.

It is common for the welder to create evenly spaced tack welds so the base materials are safely secured. Tack welds are temporary and can be removed if you decide you do not have them properly spaced to maintain perfect alignment of the components you are working on.

Welding Symbols

On proper blueprints, the welds are marked with a series of coded symbols so the welder knows the specific type of weld to create in a specific area. For the majority of manufacturers, tack welds are not commonly marked with a specific symbol. These welds are more likely to be noted as a footnote on the blueprint drawings.

The weld that is to be created on the opposite side of the material away from the tack weld will have a specific symbol denoting the type of weld that should be performed.

Tack Weld Creation

You should place small tack welds along one side of a joint where two base metals are being fastened together. You will use the same type of filler rod and the same welding process that you are going to use for the final welding of the pieces. Once the tacks have cooled, you will then going to weld the opposite side of the material to seal the joint properly.

Tack welding not only keeps the materials in a position it also keeps the materials from warping or becoming distorted while you are completing the final weld process. The small evenly spaced welds will stop overheating and will allow you to create a better final weld that is stronger and more aesthetically pleasing.

Tack Weld Problems

Tack welding is a great method of securing the metal but you must be certain that the welds you create do not have any negative effects on the final welding process. If tack welds are done shoddily the result can be cracks, weakened welds, craters, hard areas and more. Tack welding should be taken seriously.

Be very careful not to lift or move the metal that has been fastened with tack welds. You can cause the welds to pop loose and the material to shift. You can even cause serious bodily injury if you rely on a tack weld to hold the metal and the metal shifts and pins a portion of your body or falls on you.

When you create a tack weld the metal gets heated and cooled rapidly. Sometimes this rapid heating and cooling can cause the metal to become brittle.

Are Tack Welds worth the time and risk?

Tack welds are definitely worth the extra time they take to create.  The process of creating these welds is one that you will have to practice to master, but once you have it mastered this form of welding will:

  • Help you properly align and hold base materials until the job is complete
  • Give you stronger and more durable final welds
  • Help you to maintain the joint gap

Tack welding is used on a wide variety of metals and a wide range of thicknesses. Most welding professionals learn to perform this welding type at some point in their careers.

Richard Boyer
 

Richard wants to educate you, inform you, and prepare you to make the best decision you can concerning welding related items.

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