Taking the Explosion out of Explosion Welding

Written by: James Wilkey

Military personnel first noticed the ability of an explosion to fuse metals during World War I when exploding bombs caused shrapnel to embed itself in nearby metal objects. The process was then recreated under lab conditions and perfected for manufacturing. There are many benefits to traditional explosion welding. For instance, it is an ideal way to join metals that are typically difficult to bond. The process also produces stronger and cleaner bonds than those formed through melting-based processes. Today, however, a new process is revolutionizing explosion welding by completely eliminating the explosive blast from the equation. The novel process is called magnetic pulse welding, or MPW. MPW joins metals through the use of powerful magnetic forces that recreate the propulsive power of an explosion without the heat, danger, or waste.

Typical wave pattern of a weld created with the explosion welding process
Typical wave pattern of a weld created with the explosion welding process

Explosion welding is slowly being replaced with other methods because it does raise several safety concerns. First off, the process itself can be very dangerous. For example, explosion welding is conducted by spreading a chemical explosive on one of the metals that need to be joined. That metal is then detonated. The blast hurls both pieces of metal at each other at very high speeds. The force of acceleration temporarily transitions the colliding pieces into a plastic state. That brief moment of malleability allows metals to fuse together at an atomic level. Although the process creates strong and clean welds, it also produces incredibly loud noises and wasteful byproducts that limit where the process can be performed. In fact, explosion welding must be conducted in extremely remote locations.

In the last few years, many industry innovators have taken note of the drawbacks of explosion welding. These researchers have tried to capture the weld quality of explosion welding while making those bonds easier, safer, and more cost-effective to make. For example, Ohio State University scientists introduced a process called Vaporized Foil Actuator Welding (VFAW). VFAW uses the same principles of explosion welding, but on a much more controlled scale. The process centers around a superheated sheet of foil used to create a gas of “foil plasma.” The rapidly expanding gas slams the particles of the two workpieces together. The process results in a joint that is cleaner and stronger than the one produced through explosion welding. It also uses less power and produces less waste. Due to its many benefits, various industries are looking into VFAW as an alternative to explosion welding.

Explosion vs Magnetic Pulse Welding
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Currently, however, both VFAW and explosion welding are quickly being outshined by magnetic pulse welding. Magnetic pulse welding produces better welds than VFAW, and it can be used for the same applications. However, the process does it all on a much smaller scale, and without any heating or melting. According to The Economist, the process is conducted by placing two metal pieces into a machine; these pieces are spaced about a millimeter apart. When prompted, the machine sends an intense magnetic pulse into one of the pieces. The magnetic pulse charges the metal, causing it to travel the millimeter distance in just microseconds. The atoms of the two metals collide with such force that they begin sharing electrons at the point of contact, creating perfect fusion. The result is a sturdy and clean joint that supersedes those created with VFAW or explosion welding. As if that wasn’t enough, magnetic pulse welding can also be utilized in other applications, such as shaping metals. For example, the magnetic pulse can be used to propel a sheet of metal into a mold, creating any shape.

This added level of utility, combined with its cleanliness and superior weld quality, is making magnetic pulse welding a high ticket item within the manufacturing industry. In fact, companies that sell magnetic pulse welding equipment and products are beginning to draw large-scale attention. Bmax in Toulouse, France is one such company.  Founded by industry veterans and physicists, the company develops technologies that use magnetic impulse welding to shape, weld, and crimp. Due to the high demand for magnetic welding equipment, Bmax is quickly becoming a leader in metal processing systems.

Do you have experience with explosion welding? What do you think about using magnetic pulses instead of a blast? Let us know in the comments below!

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One thought on “Taking the Explosion out of Explosion Welding”

  1. MPW has great potential. I’m interested in miniaturized, dissimilar weld metal applications. If you have coil development experience, reach out to me.

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