Mechanical Glue

It usually takes additional mechanical components to provide a complete motion system, especially a highly complex motion system. The mechanical components discussed in this section include a coupling, air bearing and a gimbal. Although all are quite different, they address similar needs in various systems for precise positioning.

AIR-BEARING SPINDLES

Designed to provide superior angular positioning and velocity control, Aerotech’s ABS2000 series direct-drive, air-bearing spindles have sub-arc-second resolution at high speed. Coupled with the Aerotech A3200 controller and Npaq drive rack, the spindle resolution can be as high as 0.05 arc sec with no speed trade-offs. A low-loss brushless motor produces over 0.25 Nm (38 inch-oz) of continuous torque with very low motor losses, which eliminates the need for external cooling. The air bearings have an active preload on both vertical and horizontal surfaces and an opposing thin-film pressure maintains the bearing’s nominal gap tolerance. The spindle has a velocity ripple of less than 0.1 percent, an asynchronous error motion of less than 20 nm and total error motion of less than 100 nm. Balanced to ISO 1940 G 0.4 tolerances, the spindle’s design uses labyrinth-type sealing to minimize particle migration from the spindle. The sealing allows certification for Class 1 clean-room operation. For a vacuum supply, an integral rotary union is provided. The units target semiconductor equipment, fiberoptics, photonics and other critical industrial automation applications.

DIRECT-DRIVE GIMBAL

Providing ultra-precise angular position, rate and acceleration for development and production testing, Aerotech’s AMG position and rate gimbal mounts integrate several motion components. Combining motors, bearings, and encoders, the unit provides continuous 360-degree rotation of azimuth and elevation. Using direct-drive brushless servomotors, provides zero backlash and a cog-free design. Large diameter, matched-set ABEC-7 precision bearings minimize wobble and rotating friction, while providing high moment stiffness. The large diameter bearings allow the gimbal to handle loads up to 600 mm diameter. To maintain gimbal accuracy under dynamic conditions, cast gimbal yokes provide high stiffness. Standard options include travel limits, hard stops and brakes. Ideal for directing optics, lasers, antennas and sensors at high speed to very precise pointing angles, the gimbal targets applications in missile seeker test and calibration, LIDAR, electro-optical sensor and FLIR testing, airborne targets tracking and optical testing of space-based sensors in a vacuum, among others.

COMPLIANT COUPLING

For servo motor applications with high reverse loads and precision positioning requirements, Zero-Max ServoClass Couplings provide zero backlash and higher torsional stiffness. The couplings use 304 stainless steel disc packs and 7075-T6 aluminum hubs and center members. To avoid system resonance in servo systems, the coupling’s design provides high torsional stiffness with low inertia. Units have a torque rating range from 4.43 inch-lb (0.5 Nm) to 530 inch-lb (60 Nm) and handle system speeds up to 10,000 rpm. With 16 sizes and combinations of inch and metric hub bore sizes, the couplings match a number of servo drive requirements. A clamp style mounting hub with recessed, corrosion resistant clamping bolts is used on all models and sizes. The couplings target high precision applications including packaging machines, pick and place systems, printing machinery, machine tools and most systems that use servomotors.