When engineers noticed a shrapnel getting welded tanks thanks to high velocities, DuPont patented a controlled explosion technique in the 1960s to weld together two workpieces that were difficult to weld together using normal methods. By eliminating problems such as different melting temperatures of different materials or the mixing of metallic compounds that affect the quality of the weld, this method can be used to weld together materials that previously proved to be very difficult or even impossible to weld. This could potentially boost industries involved in metal fabrication, especially stainless steel fabrication, aluminium fabrication and steel fabrication.
In explosion welding, a clean surface is left behind on the two base metals due to the violent explosion. The pressure forms a high-quality weld between the materials. Although, a very effective welding technique, it is not very practical as it cannot be adopted by all fabricators easily.
A modern iteration
In 2011, Professor Glenn S. Daehn and his research scientist Anupam Vivek were working on electromagnetic forming, a process involves a large pulse current sent through a solenoid coil from a capacitor. Forces from the two opposing electrical fields of the two materials caused a forming action.
Those initial experiments have since then produced a process known as vaporizing foil actuator welding (VFAW). In principle, this method of welding is the same as explosion welding wherein two materials are forced together using high velocities in a controlled way. This is why both methods are classified as impact welding techniques. However, the main difference lies in the type of force that pushes the workpieces together.
Unlike in explosive welding, the VFAW uses an intense and sends it into a foil. That foil is placed between an anvil and the flyer. That is the base material that is to be pushed into the other base material, also known as the target. The flyer and target are separated by a small standoff distance through which the flyer moves in order to impact the target.
Bringing it to the world
To bring this technology to the industrial market, the researchers at OSU have been working with different industry and government partners some of which include industry giants like Honda and Ford. Moreover, the researchers have teamed up with Coldwater Machin Co. in Ohio to create a pedestal machine that feeds the foil actuator material under the flyer base material.
As of now, the team faces a significant challenge. Currently, foil coupons are fed into the work area by a coil. Once the weld is done, the coupon is vaporized. However, some of the foils are in a plastic packet, which, once the foil has been vaporized, leaves behind some debris which has to be cleaned out. Right now, they are developing a way to keep that area clean.
Although the OSU team is currently focused on using this technology in the welding front, collaborators see potential use in other production environments such as metal bending, and metal rolling and cutting, which might prove to be more effective than laser cutting.
