Cold welding is a welding process that needs little to no heat to fuse two metals together. Instead of heat, pressure is used to join the metals together, and no metal is liquefied during the process.
Welding is most often thought of as something that involves molten metal and sparks flying everywhere, however, there are many types of welding that do not fit the criteria. Here are some of the commonly used welding processes:
The Four Types of Welding
There are four main types of welding; Gas Metal Arc Welding (GMWA) also called MIG welding, Gas Tungsten Arc Welding (GTAW) also called TIG welding, Shielded Metal Arc Welding (SMAW) also called Stick, and finally Flux-cored Arc Welding (FCAW) which is also called Flux-cored welding.
One of the most common types of welding that does not include the melting of metal is cold welding. Industrial applications have used this type of welding process for nearly 100 years because of the many advantages it possesses over alternative processes. In essence, cold welding is a welding process that needs little to no heat to fuse two metals together. Instead of heat, pressure is used to join the metals together, and no metal is liquefied during the process.
How Does Cold Welding Work?
You might be wondering, how do two metals join together just through pressure? The main principle behind cold welding is the removal of the oxide layers on the surfaces of the metals being joined. Nearly all metals in normal conditions carry a layer of oxidation on them, where it is visible or not. This gives the metal a barrier that doesn’t allow their atoms to press together and bond with each other. However, once this barrier is removed, the atoms can be fused together with the right amount of pressure.
In order to get rid of the oxide layer, a number of different chemical and mechanical methods can be used. Degreasing and wire brushing are just two of the many techniques used to make sure that each metal’s surfaces are ready for joining. Both metals must also have a decent level of ductility, and then industrial machines can be used to apply a significant amount of pressure that will allow the metals to create metallurgical bonds.
Cold Welding Drawbacks
Cold welding is not perfect by any means, first of all, achieving and perfect cold welding is an extremely difficult task. The weld formed will only be as strong as the two metals themselves if the perfect techniques and methods are used. If not, the weld will be a weak point in the metal. There are a number of reasons why imperfections may creep into the weld. It typically involves the presence of oxide on the surface of the metals, surface irregularities, contamination of the surface, and others.
The oxide layer can be quite difficult to remove, as you cannot see it sometimes even if it is still there. No matter how you clean and wire-brush it, there may still be oxide residing on the surface. Furthermore, if the surface of the two metals is not prepared properly and there are imperfections on one or both of the joining surfaces, it will make it very hard for the weld to be successful even if there is absolutely no oxide on the surface.
In short, the metals must be prepared meticulously, be clean, free from irregularities and of the same shape. If not, you will be inducing a weak point into the metal, and because of these many limitations the welding industry does not use cold welding as a default process anymore.
Cold Welding Advantages
While there are some significant disadvantages to cold welding, it is important to note that there are some advantages to it as well. The main advantage to cold welding is that it takes on the strength of the parent material(s). It may seem impossible to get the right conditions to cold weld, but once the right conditions are in place, the weld created will be stronger than most others. It will definitely be hard to find a weld that is stronger than the one formed with cold welding.
Aluminium and copper are two metals that are commonly joined with cold welding as they are difficult to weld using any other method. Cold welding makes the process of joining these two metals simple, and a strong reliable weld is formed leaving the welder with a peace of mind when finished.
Cold welding is a good option to create very strong welds on flat, clean surfaces, when the conditions support it. No intermetallic compounds are formed that make the metal brittle, and this is important to maintaining the strength of the finished product.
Cold Welding In Space?
While cold welding is not a very commonly used method in the welding industry anymore, its current main application is the welding of wires. This is due to the sharp weld it creates and because there is no heat integrated into the process. Heat is known to damage wires, which is why cold welding is such a perfect option for that application.
The weld the cold welding produces is long lasting and is typically made from 70/30 zinc, brass, aluminium, copper, silver, silver alloys, nickel, and gold. Conveniently, you can buy handheld cold welders to use when working on wires that require a portable tool. These can be extremely handy and time-saving when working on a project.
Cold welding is also used for joining two metals together that are not the same material. Aluminium and copper are two metals that are commonly joined with cold welding, and this can form an extremely strong bond between the two metals. Stronger than any bond that can be formed using other methods.
This method can also be used in space, where if the metals are touching. This is used as the above mentioned regular welding processes will not function in space as there is no oxygen.
So what do you think about cold welding? Do you have any experience in this field? We would love to hear any knowledge or stories you have to share on this topic in the comments below!
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- What is Electroforming and where is it used?
- What is Electropolishing and what is it used for?
- Bandsawing – process description and design guide
- 5 Absolutely Mental Manufacturing Processes
- Laser Beam Machining (LBM)
- Plasma Arc Cutting (PAC)