Cold welding is not a new concept. Archaeologists have discovered tools dating back to the Bronze Age that were joined using cold welding. In the 1940s, the process took hold for use in modern times. Although the process is not for all types of metal, it certainly has its place in the current world of welding. Let’s take a closer look at the method of cold welding and its various applications.
What is Cold Welding?
Cold welding is just what it sounds like: welding metals together without heat. The energy required to have a successful weld is provided by pressure. No metal is heated and the metal remains in its solid state.
The metal pieces are pressed together as closely as possible, and pressure is applied. The metal atoms bond with each other and create a homogeneous mass. If done correctly, the weld is effective and ideal for certain metals.
What Types of Metals Can be Used in This Process?
The most common application for cold welding is for joining dissimilar metals which do not meld well together under heat. Softer metals that are ideal for cold welding include:
These soft metals cannot be fusion-welded since they tend to crack under heat. Metals that contain carbon, such as steel, cannot be welded together using the cold-welding process. Cold welding is also ideal for welding together wires, particularly when laying underground wires when there is a danger of igniting flammable gases if a heat-welding process is used.
What Industries Rely on Cold Welding?
The aerospace industry now uses cold welding extensively. At first, there were mechanical problems with early satellites because the motion between the surfaces was not taken into account.
Now, the benefit of cold welding allows astronauts to do repairs outside of the spacecraft without needing heat or a liquid to effectuate a weld. On the other hand, caution must be used to avoid accidental cold welding. When two like metals come together in space, and there is no rust layer, they automatically fuse together permanently.
Other industries that often use cold welding include the automotive industry and advanced fabrication applications. Often, cold welding is used for laboratory experiments.
Cold welding is used to seal containers of explosives for any type of welding where there is a physical danger presented from the use of heat.
Is Cold Welding Difficult?
If done properly and with the correct metals, cold welding is not difficult. The key is to have all metals pristinely cleaned. This means removing every bit of oxide that has accumulated on the metal. If all the oxide is not removed, the metals will not bond.
The oxide can be removed using chemicals and/or by degreasing. After cleaning with these methods, the surfaces should finally be wire brushed. Wire brushing must be the last step. Otherwise, the impurities could be pushed deeper into the metal. Check the metal’s specification sheet to be sure you are using the correct brush type and bristle materials.
If unclean surfaces are attempted to be cold welded, the weld won’t work and may have a high probability of failure.
Flat pieces work better for cold welding, so any irregularities in the metal pieces should be flattened before the weld is attempted.
Pros and Cons of Cold Welding
As with any welding method, there are pros and cons to cold welding.
Some of the pros include:
- It is the best process for welding aluminum or aluminum with copper.
- It eliminates heat-affected zone (HAZ) problems since there is no heat.
- It makes it possible to join dissimilar metals that are difficult or impossible to join using heat.
Some of the cons include:
- The need to clean, clean and clean again the surfaces that will be welded together. There must be no rust left on the metal pieces or the weld will fail.
- The environment must be free of dust or other debris in the air since any recontamination of the cleaned surface will interfere with the weld.
- It does not work for carbon steel or any other hardened metal.
- It may not work if the surfaces are irregular, so if there are any irregularities, the pieces must be flattened for the cold weld to be successful.
Contact Arizona’s Leader in Welding Supplies for More Information
The professionals at Vern Lewis can help you choose the proper tools for cold welding and answer questions you may have about this process. For more information, contact us today!