Design competition helps launch a clearly robust SL resin.
A whimsical night-light recently took top honors in a rapid-prototyping design competition. The solar energized buglike creature called Glimo along with other prototypes such as a diving mask, a model of a human nasal passage, a 3D puzzle, and a paintball marker helped the competition's host, Accelerated Technologies Inc., Erlanger, Ky., kickoff the launch of a new stereolithography (SL) resin called Waterclear 10120.
The SL resin from DSM Somos, New Castle, Del., reportedly is the first of its kind to be optically clear. It also mimics the flexural strength and modulus properties of polycarbonate, has a notched Izod impact strength on par with nylon 6/6, and sports a tensile strength similar to ABS.
Says night-light designer Lunar Designs Inc., San Francisco, the key feature tested during prototyping was the light's appearance when lit, but resin toughness and impact resistance helped the light stand up to drop tests and handling during promotional meetings. Unlike previous SL materials that are often brittle, the Waterclear's high flexural modulus also let the two-part assembly easily snap together. Glimo attaches to a child's bedroom window via giant suctioncup clodhoppers.
Good structural properties coupled with optical clarity were also key for prototype testing of the HydroOptix Mask from Herbst LaZar Bell Inc., Chicago. According to project manager, Mark Davis, the diving mask required several design features that generally are hard to accomplish in a conventional prototype model: complex mating surfaces, functional snap fits, a variety of hand finishes, and precise assembly.
The Waterclear 10120 built lens was polished to a "Level 4" finish and clear coated to further optimize its optical clarity. The lens fits inside a subframe made from another SL resin which is then snapped into the mask frame. With the addition of three production parts from a previous design, the final mask assembly looks realistic and survived rigorous underwater testing.
A SL model of a human nasal passage was built from a mathematical model generated from a CT scan by researchers at CIIT Centers for Health Research, Research Triangle Park, N.C. It is used in airflow modeling studies that help identify sites in nasal passages where toxic substances may be transferred from the environment.
According to CIIT's Julie Kimbell, conventional plastic-molding techniques can't be used to model the nasal passages accurately in life. Stereolithography provides a way to reproduce lifelike nasal passages without requiring tissue specimens. Prior to WaterClear 10120, SL models were made from a variety of amber-colored epoxy resins. However, because the nasal passage geometry is so complex, small intricate details could not be seen clearly. With the new SL resin, flow properties can easily be seen even through the thickest areas of the model.
Fluid-flow analysis is not limited to medical applications such as CIIT's nasal passage, says ATI's Todd Grimm. Designers of engine components and valve bodies can also take advantage of the material's high clarity and structural properties when testing new designs.
Although ATI chose to build all the SL models in the competition on a SLA 5000 from 3D Systems, Valencia, Calif., the material can also be run in SLA 500, 7000, and Viper Si2 machines. Typical build times for the models ranged from 6 hr for the 5.7 X 4.4 X 2.4-in. Glimo piece to 10 hr for the diving mask's 5.5 7.3 X 4-in. three-piece assembly.