Testing product design to the max
Testing product design to the max
Rapid prototyping has traditionally been seen as a way of testing whether a design will work before taking it to full production. With tooling costing potentially hundreds of thousands of dollars, it’s of obvious benefit to make sure the design works before you get to this stage.
However, while increasing numbers of designers and manufacturers are using this technology to test products, some are actually using these machines to make the products themselves. 3D Systems, for example, says use of its machines by clients has revolutionised the dental and hearing aid manufacturing process. In fact the increased use of “RP” machines in manufacturing has changed the industry accepted terms of “Rapid Prototyping” to “Additive Manufacturing”.
3D Systems sells rapid prototyping machines, materials for use with different application in the machines and a service where companies can have their CAD designs printed without actually purchasing a printer themselves. Its portfolio of 3D production printers suitable for use with polymers include stereolithography (SLA), which uses a UV photopolymer, and Selective Laser Sintering (SLS) machines, which use powdered thermoplastics.
3D Systems supplies SLA machines to a US company called Align Technologies, which have shaken up the orthodontic market. Align use the SLA 7000 and more recently the iPro 8000 SLA System to print its range of Invisalign braces. Not only are these clear and therefore less obvious for the wearer, they are also created in a unique way. It is estimated that over 50,000 aligners are made each and every day, making this the largest additive manufacturing application in the world by a wide margin.
A decade of experience
“The business has been around in the US for over 10 years but is relatively new to Europe,” says Lee Dockstader, vice president of business development (at 3D Systems). “An impression is taken of your teeth, which is then X-ray scanned and software breaks down the realignment of your teeth so that they are straightened over 24 steps.
“For each stage the software generates a computer model of the patient’s teeth and the rapid prototyping machines make a physical model of the different stages,” says Dockstader. “Then a thin bit of plastic is formed around the plastic teeth and it is this piece that forms the aligner and the printed teeth are thrown away.”
A similar manufacturing idea has already shaken up the worldwide customised hearing aid market. Ten years ago 3Shape, a small Denmark company, created a scanner and software application that revolutionised the manufacturing process for custom hearing aids. The 3Shape manufacturing process produces custom hearing aids at a much faster rate than those that are hand made as it is an extremely specialist job. “It takes a year to be able to train someone to make these products by hand so their remake rate is acceptable,” explains Dockstader.
With the 3Shape process, an audiologist takes a mould of an individual’s ear, which is then scanned and computer software works out where the internal workings of the hearing aid should go within this shape. A CAD model is created and sent to the production software, which then prints it on the Viper SLA System using biocompatible resin. Each individual hearing aid can cost up to Euro 4,000 and each machine can print a couple of hundred a day.
The majority of the world’s custom hearing aids are now made with this process. Dockstader estimates that between aligners and hearing aids alone more parts are printed per day on 3D Systems machines than all the other additive manufacturing systems combined.
Another unusual application for rapid prototyping has been found by California-based business Bespoke Innovations. It uses the 3D Systems’ SLS technology to create customised cladding for prosthetic limbs. Scott Summit founded the business with an orthopedic surgeon in a bid to offer limbs that were personalised to the user. “I wanted to create a leg that had a level of humanity,” Summit says. But there is also the added bonus that the limbs are dishwasher safe.
Bespoke Innovations scan the customer’s remaining leg and use this to create the PA shape of the prosthesis. They then interview the customer about their lifestyle and hobbies and come up with a design to overlay onto the prosthetic. Dockstader adds: “One customer was a Harley Davidson owner and so his leg was all chrome and leather.”
Source : www.prw.com
