Modelling the future

Rapid prototyping is constantly evolving and inkjet-style 3D printing using multi-material printers is one of the latest developments. Emily Pacey discovers that with relatively low costs and improvements in technology the future of this process is bright

For more than 20 years, rapid prototyping has been saving designers valuable time, money and effort in the creation of working models for a product’s all-important testing phase. The rather small field is dominated by a handful of companies, which create new technologies that broaden the choices for designers seeking the best option for a particular product’s needs.

The latest technology to come onto the market – capturing the imagination of the public more than any other – is inkjet-style 3D printing. This is the cheapest and fastest way to prototype, and holds the most promise in terms of mass manufacturing from consumers’ desktops. But it remains unpopular with designers.

’We haven’t had a huge amount of success with 3D printing, partly because the materials are very unstable,’ says Therefore director Patrick Hunt. ’We also rarely use it because we need parts that clip and fit together with tolerances of a fraction of a millimeter, not half a millimeter.’

A relatively new technology created in the 1990s, inkjet-style 3D printing is more flexible in the materials that it can use than its more stalwart forbears, which include selective laser sintering, fused deposition modelling and stereolithography. At the University of the West of England, Paul Thirkell, senior research fellow at the Centre for Fine Print Research, is engaged in a project in which artists are creating 3D forms from 2D designs. ’As well as the esoteric, artistic side of the project, we have really been testing the limits of different printers,’ says Thirkell. Working with Objet and its major competitor Z Corporation’s 3D printers, they’ve found the cheaper Z-Corp model offers greater flexibility, even offering what Thirkell describes as ’mind-bogglingly bright’ colour, while Objet achieves greater precision ’and is more of an engineering machine’.

As with any technology, improvements are made in fits and starts. The most recent and biggest advance in inkjet-style 3D printing – and in rapid prototyping as a whole – is the appearance of the first multi-material printer, the Objet Connex 500. This allows objects with hard and soft elements to be made in one go. Hunt is impressed, offering the example of a shower gel bottle that incorporates a hard cap and a soft valve to squeeze the soap through. ’The fact that you can now replicate that in 3D printing is very interesting, but there is still the problem that after a couple of weeks or two dozen operations, it gets a bit wobbly,’ he says.

The older rapid prototyping technologies, including selective laser sintering – which softens and fuses plastics and powders to create shapes – and stereolithography, which involves a bath of fluid that moves up and down while a laser hardens parts of it, remain more popular with some designers.

’There are different types of 3D technologies and some are low and some are high quality, and you get what you pay for,’ says Nottingham Trent University head of product design Paul Johnson. ’It depends on what you are looking for. If you are after lots of different quick visual models then the inkjet process is useful.’ Architects, who are not creating moving parts or handleable prototypes, are particularly fond of this method.

For precision, selective laser sintering is recommended. The method involves melting powdered plastic. ’Structurally strong, good in terms of detail and offering assembly of functional parts, but it is not great aesthetically and needs a lot of tidying up afterwards,’ says Johnson.

Selective laser sintering is seven or eight times more expensive than inkjet-style polyjet 3D printing, making 3D printing the obvious choice financially, if not practically.

But its future is bright. Hunt believes that ’the technology is going to massively improve. After all, when stereolithography came out, the models turned brittle over time and also didn’t look great. The future of 3D printing is amazing because these machines are constantly evolving’.

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