Motorized Spindles

Driving an air bearing spindle without introducing error requires integrating a motor with the bearing. We obtain frameless motors from the world’s top manufacturers, finish-machine them for improved roundness, and attach them as closely as possible to the bearing mounting face. In this way, pure torque is delivered to the bearing, with no unwanted radial, axial, or moment impulses; in addition, the torque output is not limited by transmissions or couplings.

The air bearing’s smoothness is complemented by the smoothness of the motors we install. Our encoder-commutated, brushless‑DC motors with high-power linear servo amplifiers and frequency-locked speed control offer velocity stability of .0001%. We continue to work closely with leading servo-system designers in our quest for ever-smoother motors.

Whether you perform memory-disk research, generate aspheric optics, or build liquid-mirror telescopes, Professional Instruments Company has a motorized air bearing spindle that will suffice. More on motorization.

The model 4R Twin-Mount spindle combines a high-power brushless-DC motor (liquid cooled) with a model 4R air bearing for the most demanding applications. This is the spindle to use in a rapid-cycle, start/stop operation, or when the ultimate in speed stability is required.

The model 4R Foot/Flange spindle integrates a 1hp AC induction motor with a model 4R air bearing in a convenient-to-install package. Featuring a flange for face mounting and a dovetail for foot mounting, the spindle is best suited for such continuous duties as grinding, flycutting, and turning, especially to optical finishes.

The A.C. Cube has a precision ground square motor housing that provides users with reference surfaces for alignment of the spindle to machine tool slides. The A.C. Cube employs the same 1hp AC induction motor used in the 4R Foot/Flange. It is ideally suited for continuous-running applications, such as ultra-precise grinding and flycutting.

The motorized 10R is available as a foot-mount spindle (shown), or with a flange for face mounting. We integrate a water-cooled 10 horsepower brushless-DC motor with the bearing, so there is no coupling to influence bearing accuracy or limit torque. Optional extras include high-resolution optical encoders, through-spindle pressure, vacuum, coolant, or electrical signals, and special workholding devices. Many of the world’s finest optical-surface generators are built around this spindle.

Higher-speed applications require a special air bearing design to manage the thermal effects of air-film shear. The motorized ISO spindle design is capable of 60,000 rpm with the high-accuracy/high-stiffness combination that is our specialty. When equipped with a high-power motor, this spindle is ideal for precise I.D. grinding and flycutting. High-speed memory-disk spindle stands are another popular application, where low asynchronous error motion is crucial. If you need high speed and high accuracy, the ISO spindle should be your first choice.