Welding the unweldable with smarter machines

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Mars G. Fontana Prof. of Metallurgical Engineering & Exec. Director, Honda-OSU Partnership Program, Ohio State University

We are always looking for new ways to make manufacturing more efficient. Whether it’s the data-driven reuse of components or the research and discovery of new polymers, we’re striving for optimal usage with minimal waste. But what happens when we look at solutions that challenge core physical processes as we understand them?

The next generation of manufacturing equipment will be designed to change the game. They’ll be able to reuse a variety of metals and alloys, regardless of composition. They’ll use less ore and energy, and output better shapes (truss-like, perhaps, with higher performance per mass than simple blocks). And they’ll flexible enough to produce products near locations where they are used, reducing energy use in transportation and minimizing wasteful overproduction.

And these new-age machines will also be able to weld the unweldable, a fact that has real-world impact for several major industries, including automotive and aerospace.

Currently, there are challenges when you set out to weld components made of materials that don’t “belong” together (high-strength steel + low-density aluminum). Melting temperatures are wildly different, and even when this problem is solved, iron and aluminum form very brittle compounds that can render such welds almost useless. And joining items with different shapes and flexibility properties can provide additive difficulty.

In the building of cars, for example, we see these challenges come to life, in that the strength of base metals is weakened by the welding process. The predominant method is resistance spot welding, where a pulsed current melts a stacked sheet of two or more sheets of metal and they re-solidify and fuse together. To combat this weakening, more metal is added, which adds to cost and lessens efficiency, making it difficult to achieve the end-goal—which is to create safe, fuel-efficient vehicles out of thin, high-strength materials.

So what happens when we overcome those challenges by doing things differently? Stronger metallurgic bonds and more efficient productivity.

My team and I, a research group at Ohio State University, have developed a new way to efficiently join components of dissimilar shapes and materials. A sort of “solid-state welding,” it will be 80 percent more energy-efficient per weld and possess properties that are as strong—or stronger—than the base metals used.

We use special apparatuses that vaporize something not too dissimilar from an aluminum gum wrapper with an intense pulsed current from a capacitor bank—and use the force to join metals at high speeds (2,000 mph over 3 mm of travel). If formed, cut and joined at the right velocity and angle (300–700 m/s, or roughly 600–1,500 mph and around 15° or so), native or oxidized surfaces are jetted off and a weld is created with little to no melting. 

We can leverage this technology to make better products, for less cost. And beyond that, we can also change the world for the better while we’re at it. We’re in an era where there is more copper and iron per cubic meter in our landfills than in our ore mines, and efficient usage is a core problem that needs to be addressed. And there is as much opportunity for sustainability improvements in industrial applications as there is on the residential side.

By developing new ways to weld and by innovating other manufacturing processes, we can flip the script, and live well while making the best use of our finite resources.