3-D printers are building the cars of the future

Carmakers can spend a year building a working prototype for a new car. But researchers in Tennessee have an automated system endearingly known as BAAM (Big Area Additive Manufacturing).

Most people would call it a 3-D printer, albeit a particularly large one — and it is used to print cars.

The researchers work at the Oak Ridge National Laboratory, which is exploring a number of advanced manufacturing methods. In one experiment, BAAM made most of the body and chassis for an electric replica of a Shelby Cobra, a classic 1960s sports car. The printed parts that went into the vehicle were built up using a mixture of 80 percent polymer and 20 percent carbon fiber and weighed a mere 227 kilograms. It took the team just six weeks to design, print and assemble the car.

A few companies are using additive technologies to make limited runs of cars, but 3-D printing is still too slow for mass-produced vehicles. Even so, it will quickly become part of the automobile industry, said Thom Mason, director of Oak Ridge, not just for prototyping or customizing vehicles but also for making molds, tools and dies. "Now we can print these things overnight," Mason says.

Making things with 3-D printers has captured the public imagination. In recent years, improved hardware and software has turned the basic technology — which is about 20 years old — into a broad assortment of different processes. They all rely on building up layers of material additively, using plastics, metals, ceramics and even biological feedstocks. Such printers range from desktop machines that cost a few thousand dollars to hulking monsters to print metal parts that cost more than $1 million.

The size of what could be printed used to depend on what would fit inside the machine. Now some printers, such as BAAM, are coming out of the box. MX3D, a Dutch start-up, plans to print a 49-foot footbridge across a canal, using robots fitted with steel-printing equipment. Winsun, a Chinese firm, uses a fast-drying mixture of cement and recycled construction waste to print prefabricated sections of buildings, and Achim Menges at the University of Stuttgart is printing strands of carbon fiber to make one-off architectural structures such as pavilions.

One advantage of producing something additively is that material is deposited only where needed, so there is little waste. In traditional manufacturing perhaps 80 percent of the material is cut away.

The technique also lends itself to making complex shapes in new materials that can lead to dramatic performance gains. And although 3-D printing is still slow compared with mass-production processes such as pressing steel and plastic injection molding, in some industries that may not matter too much.

"Additive techniques give you a whole new degree of freedom," said Michael Idelchik at GE Research. The company has spent $50 million installing a 3-D printing facility in Auburn, Ala., to produce fuel nozzles for the new LEAP jet engine.

GE will begin by printing 1,000 nozzles a year, but eventually the number could reach 40,000. The fuel nozzle in a jet engine is a complex part that has to withstand high temperature and pressure. Normally it is made from 20 different components. GE instead prints the part in one go, with a laser fusing together layers of a powdered "super alloy" made up of cobalt, chrome and molybdenum. The resulting nozzle is 25 percent lighter and five times more durable than the old sort.

"Additive manufacturing will definitely win a lot of ground at the expense of existing processes," said Henrik Runnemalm, the head of engines for GKN Aerospace, a British company. Some of GKN's 3D-printed components are already in aircraft and jet engines.

The technology is also used alongside traditional techniques. In one process, a 3-D printer creates a component in its "near-net shape" (close to its final form), which is then finished conventionally with machine tools.

Additive manufacturing has plenty of potential left, not least because it can change the properties of materials as it goes along. "This is totally new," Mason said. "It is one of those things that is not in our design vocabulary right now."

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