Friday, September 1, 2000
To create motion within a vacuum chamber, typical rotary
feedthrough devices use a ferrofluid or O-rings to seal the shaft or a magnetic
feedthrough device. But ferrofluids are expensive and complicated, O-rings wear
out, and magnetic couplings don't provide a positive connection, according to
Alan Clements, Harmonic Drive Technologies (Peabody, MA) Senior Applications
In contrast, ChamberLink™ from Harmonic Drive Technologies
combines a rotary feedthrough and precise harmonic drive servo actuator in one
stainless steel device that seamlessly integrates the harmonic drive with the
chamber wall, keeping the motor and input elements on the chamber's ambient side
and the geared output shaft on the vacuum side. Because the device has no
chamber-wall penetrating shafts that require seals, vacuum leakage is prevented.
"It reduces particle count, downtime, and maintenance costs," says Clements,
"because there are no seals to wear out and fail.
The vacuum is not compromised even if the motor is removed. The
company recently introduced two new sizes, ChamberLink 14 and ChamberLink 32.
Size 14 is rated at 40 inch-lbs continuous torque at 70-rpm output speed and can
provide accurate positioning for wafers and small cassettes in load lock,
transfer, and process chambers. The size 32 unit, rated at 500 inch-lbs
continuous torque, is recommended for turning indexing platens operating in
vacuum process chambers.
For more information about ChamberLink from Harmonic Drive
Technologies check out http://www.harmonic-drive.com.