Application Description
The Chamberlain Group's ceiling-mounted garage door openers have a worm that's injection molded from Minlon® mineral-reinforced nylon resin and a worm gear molded from Delrin® acetal resin. In earlier models, the parts were made of glass-filled nylon and steel, respectively.
The worm is mounted on the opener's motor shaft. It meshes with the worm gear, which turns a vertical shaft to drive a belt or chain that moves the door's operating arm along a track. The gears have an optimized double-lead design in which two sets of teeth are always in mesh. They provide a 16:1 reduction ratio to provide the torque needed to raise or lower a door.
Benefits Gained
Fights wear and noise. The gears of Delrin® and Minlon® run together quietly with minimal wear. They perform flawlessly in tests involving 25,000 open/close cycles, the equivalent of 15 years of service, according to James Chang, Chamberlain's mechanical engineering manager.
Designed-in reliability. Chang took advantage of the design freedom afforded by Delrin® and Minlon® to develop optimized double-lead gear geometry in which two sets of teeth are always in mesh. The design distributes loads efficiently, reducing the risk of gear damage; and it minimizes friction and backlash as well, according to Chang.
Reduces costs. The gears cost less than the glass/nylon and steel gears they replaced. The double-lead design and the mechanical strength of the gears also eliminate the need for a costly brake, according to Chang.
Materials Selected and Why
Delrin® and Minlon® provide mutual compatibility for low friction and wear in gear parts plus requisite levels of mechanical strength.
