Servo Coupling – Stiff or Stiff Enough?

Overview

This white paper discusses the selection of precision couplings for motion applications, focusing on optimizing performance and cost. It outlines two primary types of flexible shaft couplings: torsionally stiff metallic couplings and vibration-damping elastomer couplings. Torsionally stiff couplings minimize twisting deflection, ensuring synchronized rotation between shafts, while elastomer couplings absorb vibrations and shocks, albeit with some torsional wind-up.

The paper emphasizes the importance of torsional stiffness in applications involving servo motors and linear motion systems, particularly when connecting to ball and lead screws. It highlights that while high stiffness is often desirable, elastomer couplings can be effective due to the mechanical advantage provided by screws, which mitigates the effects of torsional wind-up on positioning accuracy.

Additionally, the document addresses the challenges of coupling wind-up, especially in systems with significant load inertia, which can lead to positioning errors and oscillations. It provides guidelines for assessing coupling requirements based on factors such as mechanical advantage, positional accuracy, and inertia ratios.

The paper concludes by recommending that manufacturers be consulted for guidance on selecting the ideal coupling for specific applications, as various designs exist to accommodate different misalignment compensation needs and installation situations. Overall, it serves as a comprehensive resource for understanding the intricacies of precision coupling selection in motion control systems.