Cold welding

COLD WELDING: Meaning, Process, Working, Advantages & Disadvantages

Hello Readers, welcome to your own website to understand each and every topic related to the manufacturing process where we transform complex content into simpler ones. In this article, we are focused to cover the meaning of cold welding, process, working,metals that can be cold welded, advantages, disadvantages, and applications.

COLD WELDING

A solid-state welding process in which joining takes place without fusion or heating at the interface of the two parts is called cold welding or contact welding process.

There should not be liquid or molten phase present in the joint in the fusion-welding processes.

Cold welding was first recognized as a general materials phenomenon in the 1940s.

After research, it was found that the two clean, flat surfaces of similar metal would strongly adhere if they are brought into contact under a vacuum.

It is just found that micro and nano-scale cold welding has shown potential in nanofabrication processes.

When the atoms in contact are all of the same kind, there is no way for the atoms to know that they are indifferent pieces of copper, this is the main reason for the unexpected behavior.

PROCESS

First of all there is a need to clean the part which we have to weld.

Cold welding process
Cold welding process

Only a short section of part is sheared.

With the help of some extension the parts are clamped in the die.

For the completion of welding there is need to apply forging force.

WORKING

The main reason why cold welding can bond two metals together without heat is the removal of the oxide layers on the surfaces of the materials being joined.

A barrier is formed due to the metal oxides that prevent the metal atoms on the materials from being pressed together and bond with one another.

The metal atoms are able to join with one another with enough pressure after the oxide layer is removed.

Various mechanical and chemical methods are used for the purpose of removing the oxide layer.

There are techniques like wire brushing, degreasing, and other techniques which are used to make sure that the metal surface is free from oxides.

The metals must also be somewhat ductile.

For the purpose of creating the substantial amount of pressure needed to create the metallurgical bond Industrial machinery is used.

USE OF COLD WELDING

One of the most famous examples of cold welding is joining dissimilar metals.

This is because when dissimilar metals are melted together, they are not able to join well.

This results in metals not joining together which can lead to weak welds or welds with cracks.

Cold welding avoids such type of problem as it relies solely on the atomic bonds formed through free electrons.

For the creation of the butt or lap joints most of the time cold welding is used.

Laboratory experiments often use cold welding.

In Industries cold welding is done on aerospace, automotive, advanced fabrication applications.

It is also most of the time used for joining wires together.

METALS THAT CAN BE COLD WELDED

The metals which are commonly cold welded needs a ductile nature.

It includes Aluminum (including unweldable grades such as the 7XXX series), Copper and Brass alloys.

The carbon content metals are not able to join using cold welding process.

HISTORY

This process has centuries of history to it.

Excavators had found the cold weld utensils that date back to the bronze age.

In the period of 1724 by Reverend J I Desaguliers the first scientific experiment was successfully done.

His experiment was fueled by the observation that when he pressed and twisted two lead balls of the same diameter together, they would stick to each other.

The bond strength is almost similar to the parent metal which was shown by testing.

Currently, the accepted explanation is the creation of a metallic bond that comes as a result of the interaction between the free ions and electrons when two metals are pressed together.

CHARACTERISTICS

This process is generally stronger than the parent material and also it has the same electrical characteristics.

Without excessive work-hardening there is a need for at least one of the metals must be ductile.

Total absence of applied heating occurs.

Surface preparation is important.

Both the workpieces can be similar or may be dissimilar metals also.

Both workpieces should be cleaned.

Short sections on the workpieces should be sheared off.

ADVANTAGES

The resultant welds have the same bond strength as the parent material this is one of the noteworthy advantages of cold welding.

The Aluminum 2xxx and 7xxx series are often not possible with other forms of welding but through cold welding it is possible.

The ability to weld aluminum and copper together which are often hard to weld with other forms of weld techniques this can be easily done by the cold welding process.

The creation of a bond between the two materials by using cold welding is very strong.

Without the formation of brittle intermetallic compounds, cold welding provides clean and strong welds.

DISADVANTAGES

It gets very difficult to inspect if the welds are made in the solid state.

The contact surfaces are sheared together where the thickness of the parts is reduced significantly.

It is highly one of a unique type of welding with respect to joint design and materials to be welded.

CONCLUSION

We have covered all the important concepts related to cold welding process. Hope you all are crystal clear with understanding all the concepts mentioned here. If you have any questions please use the comments section to get in touch with us. Till then have fun and always keep reading!

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