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A giant, high-speed 3D printer is producing large, ultra-strong steel components and weapons for the US Army. It may also have non-military uses.

The prototype printer, commissioned from 3D Systems in South Carolina for $15 million, can create objects up to a volume of 1 by 1 by 0.6 metres. The makers call it the largest, fastest and most precise steel printer ever made, big enough to print entire parts for military vehicles, such as hatches.

The US Army also had to develop a new kind of 3D-printing 鈥渋nk鈥�, or feedstock.

鈥淥ur big limitation was the feedstock material,鈥� says Brandon McWilliams of the US Army Research Laboratory (ARL). 鈥淲e needed to be able to print something with high strength for armoured or ruggedised parts.鈥�

McWilliams鈥檚 team took a nickel-alloy steel called AF96 that was developed for bunker-busting bombs and adapted it to the printing method, which lays down layers of powdered metal and fuses them with a laser.

鈥淲e weren鈥檛 sure if you could print with it,鈥� says McWilliams. 鈥淲e did not know if we would get the same properties. In fact, we got better.鈥�

The 3D-printed steel alloy turned out to be 50 per cent stronger than the same material when cast or forged, thanks to the different microstructure of the 3D-printed alloy.

The prototype printer will be operational this summer. By funding its development, the ARL hopes to pave the way for the technology and make it commercially viable, as manufacturers are keen to adopt it, but reluctant to sink in money until its usefulness is proven.

If the prototype is successful, McWilliams says steel parts could be routinely printed in the next two to three years. The printers will also produce instant spares near the front line.

鈥淲e鈥檝e been predicting for a while that a large organisation would take on this technology to supply legacy items, to get a digital inventory and to protect their supply chain,鈥� says Connor Myant at Imperial College London. Being able to print parts on demand will make it easier to repair old or obsolete kit, he says.