How Does Cold Welding Work?

Cold welding seems like it shouldn’t exist. Isn’t welding the act of melting metal until it fuses together, and therefore something that requires heat? However, welding refers to any method of binding two objects together, which is why it is even possible to weld without a welding machine. 

Cold welding is a form of welding that doesn’t require high heat to fuse two metals together. The equipment and techniques used are very different from regular welding. If you are interested in this welding technique, here is what you need to know.

cold welding examples

What Is Cold Welding?

Cold welding is exactly what it sounds like—welding that does not use heat to fuse two metals together. Instead, cold welding uses pressure to combine two materials. 

Cold welding is also called solid-state welding because the materials stay solid the entire time. This is different from regular welding, which works by melting the edge of the materials into liquid, then waiting for it to solidify into one combined piece. 

Cold welding is a truly innovative process that uses the laws of physics to create a new way of fusing materials together. It corrects many of the deficiencies of regular welding, such as the prevalence of heat-affected zones.

What Is Cold Welding Used For?

Cold welding is growing in popularity in many different industries. Many heavy industries, such as the aerospace, automotive, and manufacturing industries, are incorporating cold welding into their activities. Cold welding is also important in the electrical industry because it is a popular technique for joining wires.

Manufacturers use cold welding in very specific applications. This technique is useful when combining different metals. Heat welding only works with the same or similar metals, which isn’t always possible in industrial applications. Certain materials, including exotic metals and more delicate metals such as aluminum, also don’t hold up well to regular welding because they don’t tolerate heat.

Plus, cold welding is useful in situations when using fire is inadvisable or even dangerous. Industries that work with explosives or flammable gases use cold welding, which is much safer than regular welding. While traditional arc welding is here to stay as it is easier and more affordable than cold welding, cold welding has unique uses that fill the gaps arc welding cannot.

How Does Cold Welding Work?

Regular arc welding is simple enough to understand. The welding machine produces a flame, which melts the metal and allows two pieces to join. However, understanding how cold welding works requires a bit of physics knowledge.

Cold welding uses pressure to combine two metals. A machine presses the two metals together under very high pressure. When they are pressed so close together, the atoms in one piece of metal bond with the atoms in the other to create a metallurgical bond. The bonded atoms at the edge result in a unified piece of metal.

For cold welding to work, manufacturers need to meet several prerequisites. The metals need to be thoroughly prepared. 

  1. Manufacturers need to clean the metal as any impurities will affect the strength of the bond even more than in regular arc welding.
  2. Manufacturers need to remove the oxidation.

Removing oxidation is very important during cold welding. All metals naturally have an oxidation layer, but it is not a sign that the metal is dirty. However, oxidation prevents the metal atoms from bonding during cold welding, so it has to be removed.

Which Metals Can Be Cold Welded?

One of the benefits of cold welding is that you can weld metal that are harder to weld using arc welding or traditional heat welding. 

Most metals that can be cold welded are softer and more ductile, making them better for cold welding and more prone to breaking during fusion welding. Metals for cold welding need to be ductile instead of rigid to withstand the pressure without cracking. In terms of atomic structure, the metals need a face-centered cubic structure. These metals include:

  • Copper
  • Aluminum and some aluminum alloys
  • Lead
  • Zinc
  • Silver
  • Brass
  • Platinum
  • Gold

You cannot cold weld harder metals such as steel. You also cannot cold weld any material that contains carbon because the atomic structure is wrong.

Types of Cold Welding

The most common type of cold welding is also known as contact welding. Contact welding uses pressure welding machines to create a molecular bond that welds two metals together.

There are also many processes that people often confuse with cold welding because they don’t use as much heat as regular welding, but technically do not belong to this category. These are some of the types of welding often confused with cold welding.

Cold Metal Transfer

Cold metal transfer is not a completely heatless form of welding but uses about 90% less heat than regular fusion welding. Cold metal transfer is a type of MIG welding. The process uses a welding arc and filler wire, just like regular MIG welding, but at much lower temperatures.

Usually, a robot or machine performs cold metal transfer because it relies on precision.

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TIG Cold Welding

TIG welding is another form of welding that is often confused with cold welding because it uses so much less heat than regular arc welding. In TIG welding, a machine uses an electrical current to weld metal. When you set the machine to “cold,” it only zaps the metal with powerful electricity for a half second, generating much less heat than regular TIG welding.

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JB Weld

JB Weld is actually the name of an adhesive. JB Weld produces epoxy, a form of glue tailored to certain materials such as metal. While the brand’s marketing claims it is “the original cold weld,” you shouldn’t confuse it with the manufacturing process known as cold welding. Glue is a way to weld without using a welding machine, but JB Weld is not a form of cold welding.

Is Cold Welding Strong?

Cold welding is extremely strong because what occurs is essentially the creation of a new, unified piece of metal. A molecular bond is nearly impossible to break. No visible seam can degrade over time or create a weak point in the material. 

However, cold welding is only strong if the metals bond properly, so it is very important to clean and deoxidize the pieces properly.

Equipment Required

Cold welding is not easily accessible to DIY welders because the equipment is very different than what you have for regular arc welding. You need a pressure welding machine, which applies enough pressure to the metal for the atomic bonds to form.

Besides a pressure welding machine, which only high-end manufacturers can usually afford, you also need equipment to clean the metal, such as solvent and sponges. You also need equipment that will remove the oxidation layer, such as a wire brush.

Final Thoughts

Cold welding has been around since the 1940s, but new technology makes it easier for manufacturers to add it to their factories. This technique uses pressure to form a molecular bond between metals, making it a perfect application for situations when using heat isn’t safe.