Earlier this month, a Navy ship called the USS Essex received a huge printer. The printer and the large gray box it sits in – together weighing around 15,000 pounds – were hoisted onto the ship, via a crane, at Pearl Harbor, Hawaii. The printer does not print with ink. It prints using hot liquid metal, making it a small aluminum fabrication rig in a box.
The idea behind installing the device on the ship is that the Navy has a way to make the metal parts it might need at sea. Here’s how it works.
It reaches a temperature of 1,562 degrees
The printer, called ElemX, is manufactured by Xerox. It measures 9ft wide and 7ft tall, and will stay in its approximately 20ft long conex storage box when deployed on the Essex. It alone weighs about 4,630 pounds and requires a 480 volt power supply.
The material he prints with is aluminum and he uses aluminum wire as his raw material.
“The wire is introduced into the heated print head. Print head reaches 850 Celsius [1,564 Fahrenheit], which basically melts the wire, so you get this liquid mass of metal,” says Tali Rosman, Elem Additive manager at Xerox. “And then we activate pulses on the print head and eject [metal]drop by drop, to build the room.
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The impulses which expel the liquid metal are magnetic. The print head does not move, but a plate underneath does, allowing a custom part to take shape. “You can have the part in your hands in less than a minute from when it’s finished printing,” she adds. Once the print is complete, the creation and the plate it is attached to must be soaked in water, a process that separates the two elements.
The result, she says, is “a mini-factory in a conex box.”
She notes that the printer is not simple enough for an untrained sailor to use. “We’re not there yet,” she said. The printer training program lasts three days. In other words, it’s not as simple as loading a file for a key and hitting print.
The story of two printers
The printer currently on the Essex has a brother: the same machine model has been installed at the Naval Postgraduate School (NPS) in Monterey, California, since December 2020. “The Navy and the NPS print the same parts at sea and on land,” says Rosman. Once the ship docks, they will compare and contrast the parts made in the different environments to see if they differ. They “will ensure that being at sea has not caused any significant variations or changes”.
So what could go wrong with printing parts using hot liquid metal over a length of 844 feet Wasp-class ship that floats in the ocean?
A variable on Rosman’s radar is ship vibration, which could affect the printing process. The next concern is “the climate” the printer will experience on board, in terms of salt air or even salt water, although the printer remains protected in its large box and is inside the ship itself -same. “But in the interest of being fully transparent, since no one has done this before, we don’t know,” Rosman says. “There may be things we haven’t thought of as this printer is now at sea printing parts, there may be things none of us have put on our to-do list. risk control.”
[Related: This huge Xerox printer can create metal parts for the US Navy]
The type of objects you want to make using this printer is quite simple. The idea is to be able to create objects that could be useful at sea when a stop at a hardware store would be logistically inconvenient. “They want to make relatively simple parts that often break on a ship,” says Rosman.
Printers capable of creating three-dimensional objects can lead to “greater autonomy for Navy ships,” Commander Arlo Abrahamson, a Navy spokesman, notes via email. He says the metal items that have been printed so far on the Essex are “Common Valve Handwheels, Antenna Seal Strip Holders, Fire Hose Wrenches”, and more.
Abrahamson also notes that a previous polymer-based 3D printer on the Essex produced non-metallic parts and created some 735 items during a deployment between 2018 and 2019.
Take a look at a video showing how a metal object is made, below: