A new technology for 3-D-printing metal parts could be a cheaper and more versatile alternative to common industrial metalworking techniques. It also opens the door to new kinds of parts with unique properties that arise from the precise combination of multiple metals. Possible applications include structural parts for things like car or airplane bodies, as well as components of engines, electrical devices, or other machines.

That’s according to AJ Perez, CEO of NVBOTS, the Boston-based startup that developed the new method. The company says the technology, which is capable of printing 21 different metals from aluminum, nickel, and tin to alloys like stainless steel and nickel titanium, is the only one that can use multiple metals during the same job.

A ring made of pure titanium is 15 millimeters in diameter and five millimeters tall.

Using additive manufacturing to inexpensively make a wide variety of reliable parts out of metal would be a boon for many industries, since it would eliminate the cost of building the tools needed to manufacture new and unique parts by conventional means. Big companies like GE and Pratt & Whitney already use established additive manufacturing techniques to make high-value metal parts such as engine components, but the machines and metal powders required are very expensive. Perez says his company’s technology, which employs electricity to melt metal wire, is not only cheaper and much faster but also more flexible and efficient than those techniques and, crucially, provides more control over the printing process.

Printing metals is technically challenging for many reasons, but perhaps the most important have to do with heat. Large amounts of heat are required to melt the materials, and the way metals conduct heat complicates the process of building structurally sound parts layer by layer. The established techniques for doing this entail using either a laser or an electron beam to melt and fuse thin layers of metal powder.

These stainless-steel parts were made with the new printing method. The large hexagonal ring is 65 millimeters wide.

Perez says the new method can be thought of as a high-precision form of welding. The precision comes from a proprietary method of controlling the amount of heat used to produce every single voxel, or 3-D pixel, of a printed part. That provides a level of control over the final quality of the part that is not possible with the powder-based techniques, he says.

Right now the technology, which is still in development, can only be used to make relatively small parts. But Perez says that for small, high-value stainless-steel and titanium parts, it is already a viable alternative to a common industrial metalworking technique called casting. Casting is used in a variety of industries, including auto manufacturing, aerospace, luxury goods, and oil and gas.

The longer-term promise is the ability to print parts with unique properties that “you wouldn’t be able to manufacture any other way,” says Perez. For example, parts could feature corrosion- or heat-resistant metal on the outside and a very strong but susceptible metal on the inside. Or they could be designed to manage heat in specific ways. Companies aiming to build lighter-weight cars or planes could use the technology to make new designs that mix heavy, strong metals with lightweight but not-so-strong ones.

Later this year NVBOTS will launch a program through which industrial partners can participate in R&D aimed at refining the process and further developing the materials palette.