Industrial robots are increasingly required to perform complex, multi-angle operations with high accuracy. In many applications, a standard three-axis robotic system is no longer sufficient to meet flexibility and precision demands. This has led to the widespread adoption of the robotic 4th axis, where controlled rotary motion significantly enhances positioning capability.

Among the available rotary solutions, the Hollow Rotary Table has emerged as a preferred choice for robotic 4th axis systems due to its precision, compact structure, and superior integration capability.

Understanding the Robotic 4th Axis Requirement

A robotic 4th axis adds a rotational degree of freedom to a robot, enabling it to access multiple orientations of a workpiece without repositioning the entire robot. This is especially critical in applications such as welding, assembly, dispensing, inspection, and machining assistance.

However, a 4th axis must meet strict requirements, including high positioning accuracy, minimal backlash, stable torque output, and seamless synchronization with the robot controller. Traditional rotary mechanisms often fall short in meeting these combined demands.

Why Hollow Rotary Tables Are Ideal for Robotic 4th Axis Integration

High Positioning Accuracy and Low Backlash

Precision is the foundation of any robotic 4th axis system. Hollow rotary tables are typically designed with harmonic or RV reducers, providing extremely low backlash and excellent repeatability. This allows robots to perform precise rotational positioning, even during high-speed or high-frequency motion cycles.

In robotic applications where accuracy directly affects product quality, such as electronic component assembly or precision dispensing, this level of control is essential.

Compact Design for Direct Robot Mounting

Space efficiency is a critical factor in robotic cell design. Hollow rotary tables feature a compact, integrated structure that combines the motor, reducer, and bearing system into a single unit. This design allows the rotary table to be mounted directly at the robot base or end-effector interface without increasing system complexity.

The compact footprint enables system integrators to design flexible robotic workcells while maintaining high mechanical rigidity.

Central Hollow Shaft for Cable and Signal Routing

One of the most important advantages of a hollow rotary table in a robotic 4th axis system is the central hollow shaft. This design allows power cables, encoder wires, air lines, or vision system cables to pass directly through the rotation axis.

By eliminating external cable loops and drag chains, hollow rotary tables reduce cable wear, prevent signal interference, and improve long-term system reliability. This feature is especially valuable in continuous rotation or high-cycle robotic applications.

Performance Advantages in Robotic Motion Control

Stable Torque Output Under Dynamic Loads

Robotic 4th axis systems are often subject to changing loads due to varying workpiece weights and motion paths. Hollow rotary tables are engineered to provide stable torque output and high load capacity, ensuring smooth motion even under dynamic operating conditions.

This stability improves motion accuracy and protects the robot from unnecessary vibration or mechanical stress.

Precise Synchronization with Robot Controllers

Hollow rotary tables are typically servo-driven and can be easily synchronized with mainstream robot controllers. This allows the rotary axis to operate as an external axis, fully coordinated with the robot’s movement.

Such synchronization enables complex motion paths, improves cycle efficiency, and enhances overall automation performance.

Typical Robotic Applications Using Hollow Rotary Tables as a 4th Axis

Robotic Welding and Soldering Systems

In welding and soldering applications, hollow rotary tables allow precise rotation of the workpiece, ensuring consistent weld quality and optimal torch angles throughout the process.

Vision-Guided Robotic Inspection

When combined with CCD cameras or laser sensors, hollow rotary tables provide smooth and repeatable rotation, enabling accurate inspection of multiple surfaces without repositioning the robot.

Automated Assembly and Dispensing

Robotic assembly and dispensing systems benefit from the precise angular control of hollow rotary tables, ensuring accurate component placement and material application.

Key Selection Factors for Robotic 4th Axis Applications

When selecting a hollow rotary table for a robotic 4th axis, engineers should carefully evaluate:

• Rated torque and peak torque capacity

• Positioning accuracy and repeatability

• Hollow bore size for cable routing

• Compatibility with robot and servo systems

• Mounting interface and payload requirements

Proper selection ensures long-term reliability and optimal robotic performance.