Imagine the scenario. You go to your local car dealership for a replacement part. A bracket has sheared in your engine bay and components are rattling against each other making every journey a nightmare. Only trouble is, a replacement part won't be in stock for another few weeks.

"Not to worry Sir, we'll have one for you in an hour". Disappearing into the back, he starts up a computer attached to an Additive Layer Manufacturing (ALM) printer, selects the required part, and within the hour the mechanics begin fitting the complicated metal bracket full of hollows, bolt holes and engraved lettering - a part that didn't even exist when you walked into the showroom.

Science fiction? Not any more. We've seen for a while that 3D printing can form components out of plastics and not long ago the Urbee car, claimed to be the "world's first 3D printed car" competed in the Automotive X-Prize.

The ALM technology is seeing increasing use in industries such as aerospace and motorsport, which have high demand for very specialized and relatively low-volume parts. Normally, these parts would be incredibly expensive thanks to the materials they're made of and the complex designs that would require casting, machining or forging.

Complication is no problem for ALM printing, and it's no more difficult for the system to produce a part of incredible intricacy than it is to make a solid block of metal. The object is simply built up, layer upon layer, at a microscopic level by thin layers of metal.

Controlled by a Computer Aided Design (CAD) system, layers of metal power of between 20-30 microns (less than a thousandth of an inch) thick are spread on a platform by a recoating arm, and then a precision laser melts and welds the power beads together. The platform then drops by another 20-30 microns, another layer is spread, and again the powder is melted together. The process is repeated many hundreds or thousands of times depending on the object being constructed to form shapes that are not only incredibly intricate, but very light and of equal strength to a more traditionally formed piece. There is also significantly less waste.

Urbee 3D printer car

Urbee 3D printer car

Some impressively complex shapes have been produced so far, including interlocking chain-mail and hollow honeycomb-like structures.

One firm currently using the technology is the European Aeronautic Defence and Space company (EADS), who builds components for the Airbus, satellites and helicopters. However, the technology is catching the eye of the automotive industry too. The McLaren and Force India Formula 1 grand prix teams are believed to be using the technology already and the Daimler company even hold shares in EADS.

Construction is currently limited by the machine size - a foot square by two foot deep - but as the technology progresses the limitations are sure to be reduced.

It might be a while before you can walk to your local garage and have them print you a car, but it might not be so long before the components themselves have been printed, offering greater strength and reduced weight over their forebares.

[Evo Magazine]