RENSHAPE® STEREOLITHOGRAPHY MATERIAL USED ON GLAUCOMA EARLY DETECTION UNIT HOUSING
30 September 2003 - Huntsman Advanced Materials

RenShape SL 7560 photopolymer produces extremely accurate, complex parts with ABSlike durability. It is the only SL material currently available that produces functional prototypes that can be assembled using self-tapping screws without cracking. With its combination of rigidity and durability, SL 7560 effectively simulates production parts that have been injection moulded from ABS thermoplastic.

The SL housings for the new optical equipment were built by FineLine Prototyping in the US, for the manufacturers, Welch Allyn.

“We chose RenShape SL7560 for the housing prototypes because it offered us the
strength and durability needed for the functional prototypes along with the accuracy
required to ensure complete matching of multiple mating surfaces,” explained Rob
Connelly, President of FineLine.

The housing also had to be able to retain light to perform in sensitive optical tests. The opaque colour of SL 7560 allowed FineLine to minimise the amount of paint used to coat the housing to eliminate light transmission, as multiple paint layers can reduce accuracy when the parts are assembled.

FineLine used Welch Allyn’s CAD data to produce a series of housing design iterations on a Viper™ SL system. Each set of six prototypes took about a day to complete with the fast processing SL 7560 material. As each model was built Welch Allyn engineers worked on the prototypes to make further refinements. This new design data was then sent to FineLine to produce the next set of housings.

Once the engineers, sales and marketing teams at Welch Allyn were all satisfied, the unit was put into production.

“Designing the optical housing and building the prototypes was complicated because of the number of advanced functions featured on the glaucoma detection equipment,” said Steve Slawson, Engineering Specialist, at Welch Allyn. In addition to holding the optical lenses for the unit, the housing is the support base for light meter and camera control circuit boards and infrared LEDs. It also carries small triangular details to aid alignment of the patient before the test is done.

“As the operating characteristics were refined, engineers changed apertures and lens diameters, altering the shape, size and placement of the various components of the housing,” continued Slawson. “With the multiple design iterations required, the processing speed and accuracy of the RenShape SL material were key to moving the project ahead in a timely manner.

“With its ABS-like performance, SL 7560 met our needs for a material that was durable and accurate enough to be used in functional prototypes that were packaged and shipped around the country and withstood frequent handling without breaking,” concluded Rob Connelly.

The glaucoma detection unit will be available worldwide from this autumn.

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