While we see the world in three dimensions and expect nothing less from the products we use, the reality is that manufacturing is far easier in two dimensions. Laser cutters are no exception. Once a costly machining tool found only in industrial machine shops and laboratories, recent advancements in control have reduced prices to bring them to the casual user or hobbyist.
Laser cutters are typically designed to cut 2D parts from a single 2D sheet of material. Adding this third dimension to these parts would be potentially game-changing, an important new capability for an old workhorse. For the US Army, this is not only a minor matter of cost or convenience: our soldiers in forward bases are often isolated hundreds of miles from the nearest manufacturing center, and being able to rapidly make replacement parts in the field could save their lives. The technology could improve the quality of life in developing countries as well.
Inspired by the ancient Japanese art of origami, folding 2D materials to create 3D shapes is widely used in applications ranging from balloon stents in heart surgery to solar panel arrays on the International Space Station. At the US Army Research Laboratory, we recently demonstrated for the first time the creation of complex three dimensional parts directly from a blank sheet of metal using only a laser cutter. The power of this technique is clear in the below video, showing the steps in our process from initial marking to cutting to the final out-of-plane folding, all in minutes without any need for handling. Moreover going from fabricating one part at a time to thousands is trivial.
You may be wondering: how is that possible? It turns out to be simple. At its core, a laser cutter is merely a focused light source that, at high enough power levels, heats the metal so that material leaves the surface. If instead, we set the laser to a lower power level, we can cause controlled heating instead of cutting. And this heating causes relative expansion, which in turn allows the workpiece to be deformed or bent in a process known as laser forming.
One of the most powerful aspects of laser forming is that the direction the metal bends can also be controlled. If we scan the laser quickly, we create a difference in temperature down through thickness of the metal sheet which causes bending toward the laser, an effect known as the thermal gradient mechanism or TGM. If on the other hand, we scan the laser more slowly, heat is able to spread all the way through the thickness and a temperature difference is instead created laterally, which can be used to generate bending away from the laser through what is called the Buckling Mechanism or BM. This means up and down folds can be easily created in the same part:
Laser forming origami has opened up a wide range of possible parts from cubes and coils to arcs and cylinders, with a few examples shown above. While we have worked with metals here, a wide variety of materials can be laser formed including glass and crystalline semiconductors.
Beyond creating individual parts, we have also explored using this same approach to fold and position multiple parts without human intervention, another important innovation. By creating an optical reflector system this way, we were able to reflect the light from the laser cutter to etch the letters ‘ARL’ onto a part of the metal originally inaccessible on the underside of the sheet. With further development, this same technique could allow complete assemblies to be built directly in the laser cutter itself.
Cutting and folding with a laser cutter brings an important new functionality to a widely available tool. It is now possible for the casual user, with minimal effort, to use their laser cutter to create three-dimensional parts. While it is difficult to envision what uses this may enable for both the engineering and maker community, we certainly feel we are far from exhausting the capabilities of our process.