Metal 3D Printing Chills Out

Manufacturing has been forever changed by the introduction of 3D printers, which enable the inexpensive production of complex, one-off parts and facilitate rapid design iteration. This is accomplished through a process that builds objects layer by layer from a digital model. Traditional manufacturing techniques, on the other hand, often involve significant costs and lead times when creating bespoke or custom parts, but 3D printing can produce these items quickly and affordably. Designers and engineers can iterate designs rapidly, testing and refining prototypes without the need for extensive retooling processes.

The versatility of 3D printing has led to experimentation with a wide range of materials. Most commonly, these printers use some type of plastic, such as PLA or ABS, to manufacture objects. Plastics offer a good balance of strength, flexibility, and ease of use, making them suitable for a variety of applications. However, the reliance on plastics limits the scope of 3D printing applications, especially where higher strength, heat resistance, or durability is required.

For applications that demand greater strength or specialized properties, metals can be an excellent material choice. Existing systems that work with metal rely on high-power lasers to fuse metal powder into solid objects. While this technique allows for the production of complex metal parts with excellent mechanical properties, it remains more experimental and less accessible than plastic 3D printing. But a team of Rice University students demonstrated that there may be a more practical path forward with their innovative, low-cost cold spray metal 3D printer prototype.

The team was inspired by existing cold spray technologies, which use velocity, rather than heat, to make metal powder conform to the shape of, and adhere to, a substrate. While this technique is presently used to coat surfaces, they realized there was an opportunity to leverage the technology, with some modifications, for additive manufacturing.

A prototype printer was developed that contains a pressure vessel that heats and compresses nitrogen gas, which is fed in from a gas tank. In the pressure vessel, the gas is heated to 842 degrees Fahrenheit, but this is only to increase its velocity as it exits the nozzle. It quickly loses its heat and does not melt the metal powder. As the metal (copper was used in this case) comes into contact with a substrate, it adheres to it. Precision application of the powder allows for objects to be created by additive manufacturing.

Existing metal 3D printers can be very expensive — upwards of a million dollars in some cases — but by keeping things simple, this prototype device only costs about $5,000 to construct. With some further work, that could potentially be reduced to the point that metal printing could become mainstream. Further testing and refinement would be necessary before there could be a metal 3D printer in every home, however. The pressure vessel can be dangerous to operate, and metal powders can also be toxic if inhaled. In any case, this work is certainly a step in the right direction for additive manufacturing.