Pronto Prototypes For Full Testing

At one time, in the not too distant past, if you had said that it would be possible to connect a device to a computer and print a solid object, people would have assumed you were talking about science fiction. Nowadays, however, that fiction is a reality, with more and more people and businesses being switched on to the potential of 3D printing.

The mid 1980s saw availability of the first commercial 3D printers, which used stereolithography – a technology that is still used today. However, it is the more recent development of polyjet matrix technology that has seen 3D printing become more widespread. Generically referred to as material jetting, this method forms object layers from liquid photopolymer emitted by an inkjet-style, multi- nozzle print head. Each layer is set using a powerful UV light before the next layer is printed.

One UK company to embrace the technology is Rutland Plastics. The injection moulding specialist provides a full range of services from design, through making the mould, carrying out the moulding and the machining, to final assembly services. Having identified prototyping as a gap in its offering, the company first started looking at 3D printers around six years ago, but didn’t initially find anything to suit its needs. "The 3D printer we looked at then offered quite a cheap and quick way to print prototype parts, but they were very fragile. It was good for checking form and fit, but in most cases they weren't really functional,” says marketing manager, Stuart Lovett.

A few years down the line, the company came across the Objet Connex. Unlike many alternative 3D printers on the market, the Objet Connex can print multi materials. In fact, it was this feature that was the deciding factor in Rutland Plastics’ choice of 3D printer.

"With the Objet Connex there are two cartridges with two different materials, so you can either print the material that is in the cartridge, or these materials can be blended together to produce what are called digital materials,” says Lovett.

"The end result is that in excess of 100 different materials are available and they can be anything from the equivalent of polypropylene, ABS, and transparent materials to rubber- type materials. This means the prototypes we get are fully functional – they can be painted, drilled, machined, even chrome plated.”

The maximum build size of any part produced on Rutland’s Objet Connex 350 is 342 x 342 x 200mm, although larger prototypes are possible by joining two or more smaller pieces. The time it takes to produce an item will depend on its size – the smaller the item the less time it will take – but Lovett reckons that a typical undertaking can be produced over night, drastically reducing lead times. And it’s not just time savings that can be made: Lovett cites a figure of £200 to print a cavity that can be used as an alternative to an aluminium tool that would cost around £3000 to produce!

Importantly, the prototypes Rutland produces using its 3D printer are suitable for full testing, often negating the time consuming and costly need to produce a mould tool, which might then have to be changed afterwards. In practical terms, cheaper and easier prototypes that can be fully tested also mean that it costs less and is more straightforward to produce optimum designs.

In an example that Lovett refers to, one of Rutland’s customers tasked the company with redesigning a specialist draining pump. The customer was concerned that the inlet on the new design would allow some of the water to flow back out of the unit and suggested an alternative that, while it addressed these concerns, would have resulted in reduced overall efficiency. To solve the dilemma, Rutland suggested that a prototype of each design be produced on the 3D printer. Armed with these, the customer was able to carry out full product testing on both versions and ascertain that there was no risk of flowback on Rutland’s original, more efficient, design.

"None of the other printing process available would have been able to make a prototype that withstood that kind of testing,” says Lovett. "And to make it by some other method would have been too expensive. This way they got the prototype relatively cheaply, proved the design and went ahead and modified the tool to get the best possible output from their product.”