Imagine a machine where you could pop in a unique object and get an exact copy back. Unrealistic? Expensive? In fact, it's achievable and cheap, and happening right now at the University of Greenwich.
What is rapid prototyping?
It's a process that can make a prototype of a machine part or toy, for example, in a matter of hours. The manufacturer can then take that prototype away, test it, come back to us for fine-tuning, and have it in production in days.
How does it work?
A company can either provide a computerised specification, known as a CAD file, or a model of the item. The model is popped into a scanner, which makes a three-dimensional virtual model. The company can even bring a drawing and the team will convert it into the standard technical language (STL) understood by computers.
The information is fed into a 'fusion deposition machine', which builds up a model, a layer at a time. "It's a bit like an inkjet printer, with the print head crossing the page again and again," says Ian Cakebread, one of the university's engineers. "It builds up layers of acrylic plastic and is accurate to 0.25mm. The detail is so good, the Imperial War Museum recently worked with us to reproduce a finely engraved war medal."
Working with Delphi Diesel Systems
Rapid prototyping has proved to be highly successful for Delphi Diesel Systems Technical Centre, which is based in Gillingham. Paul Charman, centre manager, says: "Delphi develops high pressure Common Rail Pumps. We also produce prototypes for development teams and supply to our customers. It is vital that these prototypes are made to the highest quality and delivered on time.
We have been associated with Greenwich for some time. The availability of a local centre where we can develop models of new components in a few hours is a significant advantage and has allowed us to shorten our own lead times. We have used models produced by Greenwich to make aluminium castings for our prototype pumps and these are now on test vehicles located throughout Europe."
A clear commercial advantage
Ian Cakebread says: "Before, an engineer would produce drawings of the new product and then a modeller would manufacturer it using conventional machine tools. The development process could last months. Now we can offer local manufacturers not just the machinery but the expertise in IT and engineering to help them develop products quickly and cheaply."
The university has used rapid prototyping to make a robotic hand, sports science equipment, industrial moulds and engine parts. Projects under consideration include architectural models and scale models of ships.