"In terms of trying to assess design and mechanical performance of the product in actual use conditions, it was really good."
It cost about $6000 to make the prototypes by 3D printing, versus up to $20,000 by injection moulding. Prototyping is a critical step when the cost of producing the steel moulds for a production run can be $25,000.
"The trick is to get the design correct before you commit to the tooling, because if you get it wrong it can be very expensive to undo any design errors. That's where 3D printing is fantastic for the injection moulding industry," Galantai says.
The language of 3D printing is the STL file, a format used by computer-aided design (CAD) software. Working in a similar way to an inkjet printer, a 3D printer interprets the STL file, then deposits successive layers of plastic or metal powder about 0.1mm thick, each of which is fused by a precision laser beam.
The process, called sintering, can produce objects with complex internal shapes. It has long been used for prototyping, but is increasingly delivering finished products.
"It is starting to be feasible for high-value products where you can actually afford to make the real thing," Diegel says.
Diegel has developed his own sideline - making electric guitar bodies. Using a machine at Massey made by German company EOS, he churns out three nylon bodies at a time, which takes about 34 hours.
Diegel, who plays guitar, printed his first one to see if it could be done. "It was so good that I decided to set up a start-up business selling them."
Although the non-traditional shapes may not be to the taste of a guitarist such as The Who's Pete Townshend, notorious for smashing instruments on stage, their resilience could be a selling point.
"You could throw one against the wall without worrying about it breaking," Diegel says.
The designs are to some extent determined by the size of the sintering machine.
"It's the biggest I could fit in the machine."
Musical instruments are a good example of the kinds of high-value items 3D printing is suited to. Diegel expects his guitars to sell for $4000 to $5000.
The process makes possible designs that simply can't be produced using other manufacturing methods.
"For example, 3D printing would let you build an acoustic guitar with an individual tuneable acoustic chamber for each string."
Music might be food for the soul, but won't help you walk again if your hip crumbles, or hear if your ears fail. Another application of additive manufacturing will solve both those conditions, however.
The process is being used to make bone replacements with the same lattice structure as the human skeleton, which has the double benefits of lightness and being suitable for bone to grow into.
Diegel says an Italian company is producing tens of thousands of replacement hips using the technology.
On Auckland's North Shore, meanwhile, Plastic Design Technologies is making hearing aids.
The technology's advances are showcased each year at Euromold, a German trade show.
The Economist reports that last December's show featured 3D printers ranging from car-size to desktop models, and 3D-printed items as various as artificial limbs, aircraft door hinges and high-fashion clothing creations.
Anthony Doesburg
