When you think about welding, you make a mental picture of two metals joining under very high temperatures, preferably involving molten metal. For this reason, cold welding goes against your fundamental belief of what welding means. But why is cold welding generally discouraged in the industry?
Cold welding isn’t necessarily bad; it’s just impractical for most circumstances. Since the metals must be deoxidized and smoothened before welding, it can be pretty difficult to get perfect welds with most cold welding techniques.
In this article, you’ll learn all you need to know about cold welding and why it’s an important welding procedure. Also, I’ll outline some of the most practical applications of cold welding and some of the disadvantages that make cold welding look bad.
What Is Cold Welding?
Defining cold welding can be very complicated. Since it encompasses a wide range of very different welding processes, different welders have their uniquely correct opinion of cold welding. However, we’ll use the commonalities between all cold welding procedures to curate an acceptable definition.
Cold welding refers to any welding procedure that doesn’t require as much heat as conventional welding. Depending on the specific process you have in mind, the heat output can be very little, and it can also be almost as hot as natural welding.
Cold welding is advantageous and it’s very easy to imagine situations where you’ll need a cold weld. While most welders will avoid cold welding if possible, it’s passably strong, with the ability to keep up with regular welding in some cases.
There are many different types of cold welding, causing the complications that come with the definition. While some types of cold welding require pretty high temperatures that make them not very different from regular welding, others occur at regular room temperature with other factors facilitating the weld.
In the next section, you’ll learn the different types of cold welding and the situations where they work best.
Types of Cold Welding
As mentioned above, not all types of cold welding are really cold. Some are so hot that you’ll be amazed at how they justify referring to the process as “cold” welding.
Without further ado, here are the major types of cold welding, some of which will change how you regard cold welding.
- Cold Metal Transfer
The cold metal transfer technique isn’t cold welding; it can be more accurately described as low-heat welding. It is a metal inert gas or tungsten inert gas welding process that uses about 10% of the heat of traditional welding procedures.
The heat is introduced to the metals for the fraction of a second, giving out just enough heat to join the metals. The cold metal is best for metals that could melt under too much heat, as the heat output will only join but not melt the metals.
If the metals involved are too soft to sustain 10% of the heat of the conventional welding technique, there are real cold welding techniques as explained below.
- Contact Welding
In the case of contact welding, the metals are joined with pressure instead of heat. This process is a bit more complicated than simply pressing two metals against each other to join them together.
Before starting the process, the welder must first ensure that the oxide on the surface of both of the metals is removed. This surface oxide is what prevents the atoms of two metals from bonding upon normal contact.
After removing this oxide, the two metals can be joined under great pressure to create bonds between the atoms of the metals. Understandably, pressure welding machines apply the pressure to create the bonds, as it will take much more than a regular press to join two metals via contact welding.
While cold welding is the best for specific metals, their applications are way too specific to be a general welding procedure. Unless you have the right metals in the right conditions, it will almost always result in a bad weld.
Advantages of Cold Welding
Cold welding isn’t necessarily best. There are some specific instances where it’s much better than any other welding technique out here. Here are some of the most important advantages of cold welding that make it stand out from other welding techniques.
- Best For Aluminium Welding
Aluminium, amongst some other types of metals, is unable to withstand the insane heat from regular welding techniques. When trying to join aluminium, you don’t have plenty of options. In this case, cold welding comes in very handy.
- Joins Dissimilar Metals
When joining two dissimilar metals, using cold welding is almost always the best option. Other heat-based welding techniques can be difficult to join using conventional welding techniques due to the differences in the qualities of the metals.
- It’s Strong Enough
While cold welding is not the strongest welding technique out there, it’s strong enough to create a weld that’s just as strong as the weakest parent metal. In most cases, this is usually strong enough to achieve the welder’s aim.
In cases where cold welding will produce a weak weld, it will be impractical to use. Unless in the specific circumstances where it’s recommended, you should generally avoid cold welding.
Why Is Cold Welding Bad?
If cold welding was better than the conventional welding techniques, it would have become the industry standard. Here are some of the major disadvantages of cold welding that make it pretty difficult to recommend for most cases.
- Only Applicable For Specific Types Of Metals
Cold welding only applies to specific types of metals. If a metal has gone through any serious hardening process, it will be impossible to join it using any of the cold welding techniques. The metals you’re joining through cold welding must not contain any form of carbon.
- It’s Very Complex
Cold welding can be quite complicated, given the different procedures required to achieve a good enough weld. Before it can be possible to join two metals through any cold welding techniques, they must be smoothened and deoxidized.
It’s also impossible to join some metals with cold welding due to their shapes. However, you don’t always get to join regularly-shaped metals.
