High-precision industrial spindles, such as those used in rotary stages, are crucial for applications requiring absolute precision, including semiconductor wafer processing, imaging, and inspection. Beyond the semiconductor industry, air bearing spindles are also vital in optics production, scientific research, and even automobile painting.

Air bearings, also known as fluid film bearings, utilize pressurized air to reduce friction, similar to how liquid or mechanical lubricants work. The compressed air acts as a cushion between the spindle’s rotor and stator, as well as providing stiffness, enabling highly reliable high-speed and precise movement. The complexity of predicting the performance of air bearings is rooted in nonlinear differential equations, but the benefit is seen by minimizing moving parts and wear resulting in enhance reliability. One critical design/integration aspect of air bearing spindles is the high degree of precision gained when paired with slotless motors.

Low-profile, large through hole BLDC motors are particularly suitable for spindle applications due to their large internal aperture, which accommodates optics, cabling, or prisms, while remaining compact enough for deep system integration. Another benefit of using traditional slotless or ironless stator slotless motors for air bearing spindles is architectural, due to the reduced, or in some cases, elimination of attractive forces between the rotor and stator. The lack of a stator iron enables a thinner, lighter weight, and ultimately more mass efficient spindle, saving both volume and mass.  Finally, the lack of cogging inherent in slotless motors provides a smooth rotational output and avoids even the smallest disturbance torques that can translate to the workpiece.

ThinGap’s TG Series of slotless BLDC motor kits are ideal for high-speed air bearing spindle applications due to the lack of iron in the stator, leading to zero radial and axial forces between the rotor and stator. The slotless, ironless stator delivers smooth, zero-cogging motion, making these motors perfect for spindle use. The TG Series has the added benefit of zero hysteretic and Eddy Current drag, ensuring true bidirectional repeatability in both angular and vertical movements, while also making it exceptionally efficient at high speeds. Lastly, the TG Series ironless stators boast harmonic distortion below 1%, and provide a linear current to torque output throughout the entire torque range (up to the peak torque limit) reducing servo induced disturbance and ultimately improving torque, and velocity control.

ThinGap’s TG Series of slotless motor kits stands out as an industry leader for air bearing spindle applications. With standard kits ranging from 29 to 190 mm in outer diameter and continuous torque outputs from 0.14 to 9.46 N-m, these motors are always cogless, low-profile, large through hole, and high in power density. Available in standard and modified configurations, ThinGap’s TG Series is the optimal choice for air bearing spindle motors.