To make a device that helps sleep-apnea patients breathe easier and sleep more comfortably, Airway Management Inc., Dallas, switched from an investment casting to metal injection molding (MIM) for a key structural component. The Thornton Adjustable Positioner (TAP) holds the patient's lower jaw in a forward position. This keeps the jaw from falling open during the night and causing the patient's airway to collapse. This helps maintain a clear airway to reduce snoring and improve breathing.
The appliance consists of a metal core surrounded by a thermoplastic called Thermacryl that softens when heated and can be molded to the patient's dentition when seated in the mouth.
"Previous generations of the TAP device employed investment-cast-metal cores that needed to be machined. "The switch to MIM and Catamold feedstock from BASF Corp., Florham Park, N.J., let us achieve tighter tolerances," says Airway Management President Lauralee Gunby. And the injection-molded parts are stronger, sleeker, and more comfortable for patients."
Catamold is a granulated (powdered-metal) feedstock for MIM. The composition used in the TAP cores is a mixture of Panacea (nickel-free) stainless steel and proprietary polymeric binders.
"MIM produces near-net-shape components in fewer steps compared to investment casting and machining. Secondary operations are minimized and this reduces part costs," said Uwe Liebelt, vice president of BASF's Inorganics business group in North America. "Multicomponent assemblies that are machined or investment cast can be injection molded as one piece using MIM."
TAP cores are injection molded by Smith Metal Products. "MIM let us incorporate more geometric features so the device works better and is more comfortable for the patient, says Mike Brown, a spokesperson for the Minneapolis-based molding house. "Panacea stainless steel beat out titanium because it has greater mechanical strength, better resists corrosion, and is nickel and allergen-free a requirement for many medical devices."
The FDA is currently reviewing the newest TAP device. Other versions of the product are currently available.