Automotive and manufacturing industries are typically engaged in working with dissimilar metals. However, joining dissimilar metals come with its own sets of challenges. The major challenge is that when these metals are melted together, they tend not to join too well. This further results in weak welds or weld cracks.
Cold welding or contact welding helps do away with this challenge because they work on the principle of physics and material science. Cold welding is an interesting process that allows the joining of metals without any heating requirements. In other words, the cold welding process does not require heat input to cluster metal pieces, and metals are never molten at any stage.
Cold welding is not only used for joining metals but also for joining wires. For this reason, cold welding is also quite commonly used in laboratories or industries such as aerospace.
What Is Cold Welding?
Cold welding is a process that combines two metals by creating enough pressure to form metallurgical bonds. Cold welding has a history dating back to 700 BC. However, this welding process has become more refined and sophisticated over time. The first documented cold welding experiment can be found in the works of Reverend J. Desaguilers in 1724.
Also known as cold pressure welding or contact welding, this process is not used, unlike other welding processes that use heat or molten material to club two clean metals together. Since the process does not involve any liquid metal or heat phase, they are called cold welding.
How Does Cold Welding Work?
The cold welding process applies the fundamentals of physics and applied material science to fuse two materials. By applying metallurgical force to the metal pieces, the surface roughness of the metal is reduced, and other minor surface irregularities are also resolved.
Applying pressure and ambient temperature encourages atomic bond formation through free electrons. There are specific prerequisites to be mindful of before initiating the cold welding process.
Firstly, one must remove enough oxide layers from both working metals. Secondly, the joint’s geometry must be prepared, and any surface irregularities must be absent, as flat joint surfaces work best.
Different cold-pressure welding machines can be used to achieve the required pressure and temperature to weld metals together.
Advantages of Cold Welding
Here are some advantages of applying cold welding.
Low Risk of Metal Damage:
Since traditional welding methods require heat, there is a high risk of heat distortion. On the other hand, cold welding does not require heat. Thus, there is a minimal risk of metal damage due to heating.
Work On A Wide Variety Of Metals:
Traditional welding methods frequently require additional materials such as solder, flux, or filler to join the metals. These materials are not required when cold welding.
For instance, cold welding allows the joining of dissimilar metals like zinc, aluminum, or copper alloys without any additional material requirement.
Better Finished Material:
Cold welding can join metals with high precision, making it useful in applications where accuracy is essential. Moreover, the cold welding process results in clean and strong welds.
The physical strength is sometimes comparable to that of the parent metal. Cold welding using a hydraulic press machine produces finished products with exceptional physical strength.
Time and Cost Effective:
The entire process is time-effective and leads to no deformation of metals. In addition, cold welding requires less energy and materials than traditional welding methods, making it a cost-effective alternative. And, because cold welding generates no hazardous waste, it is an environmentally friendly method of joining metals.
Disadvantages of Cold Welding
Here are a few certain disadvantages when considering cold welding to weld metals:
Increased Preparation Time:
The preparation time before initiating the cold welding process itself is time-consuming. Moreover, if the surface of the metal is irregular, fusing via cold welding can be challenging.
High Preparation Wastage:
A good portion of metal or material is at risk of wastage in the preparation process, such as cutting, shearing, or brushing.
Limited to Certain Metals:
Cold welding is sensitive to the type of materials used. As mentioned previously, cold welding can only be worked on ductile metals and metals with no carbon content.
Although cold welding produces an extremely durable bond, joint strength can be limited in some cases, particularly in high-stress applications. Oxide layers, surface irregularities, and other factors can contribute to contamination, which can further cause weak joint strength of metals.
Applications of Cold Welding
Cold welding is used for various purposes in different industries and for fusing different types of metals. Ductile materials and metals are commonly used in the cold welding technique.
Such a technique can only be used when using both working metals with similar atomic structures. Here are some of the widely used metals on which the cold welding technique can be applied:
- Copper: Copper is widely used in electrical applications, and cold welding is an efficient method of fusing copper wires.
- Bronze: Bronze alloys are typically used in sculptures and bearings. Cold welding can be used to join bronze parts without affecting their properties.
- Brass Alloys: Brass is a copper-zinc alloy used in plumbing fixtures and musical instruments. Cold welding is an efficient method of joining brass parts without the use of solder.
- Silver Alloys: Cold welding is an effective way to join silver and nickel parts. Silver is another soft, malleable, corrosion-resistant metal commonly used in the defense and aeronautical industries.
- Gold: Gold is a soft, malleable metal frequently used in jewelry and electronics. Many jewelry makers use cold welding for joining gold parts.
Other commonly used materials that can be joined using cold welding are stainless steel, aluminum, zinc, and nickel. It should be noted that cold welding cannot be used to join carbon-containing metals.
In other words, some of the widely used applications of cold welding include:
- Welding similar or dissimilar metals
- Welding wires together, mainly underground cables.
- Seal containers, especially containers with explosives
In summary, the applications of cold welding are suitable in welding materials when there is a risk involving heat.
Cold welding has taken years to become a familiar welding technique in manufacturing, automotive, and related industries. This was partly because on-ground engineers failed to visit existing works and upgrade themselves to the latest practices.
The applications of cold welding are so diverse that various industries have realized the potential of applying this technique to join metals and materials together.
About the Author:
Vincent Hua is the Marketing Manager at TSINFA. He is passionate about helping people understand high-end and complex manufacturing processes. Besides writing and contributing his insights, Vincent is very keen on technological innovation that helps build highly precise and stable CNC Machinery.