HOW PNEUMATIC ROTARY UNION WORK?

A pneumatic rotary union, also known as a pneumatic swivel joint, is specifically designed to transfer compressed air or other gases from a stationary source to a rotating part. These devices are crucial in many industrial applications where continuous rotation and the transfer of gases are required. Here’s a detailed explanation of how a pneumatic rotary union works:

Description of the structure of the pneumatic rotary union
The pneumatic rotary union is a rotary connector driven by air pressure, which is mainly composed of a rotating part and a fixed part. The rotating part includes the rotor and the bearing under the rotor and the fixed part includes the stator and the sealing ring above the stator. The structure of the rotor and the stator is relatively simple, usually there is a gas flow channel on the rotor and after the gas enters the channel from the gas source, the movement of the rotor is driven by pressure and then the rotation of the rotor is realized, so as to achieve the role of rotary connection.

Basic Components of pneumatic rotary union
1. Stationary Housing：
– This part remains fixed and is connected to the stationary source of compressed air or gas.
2. Rotating Shaft or Drum:
– This part rotates and is connected to the rotating machinery, such as a rotating tool, spindle, or other equipment.
3. Seals:
– Seals are critical components that prevent gas leakage between the stationary and rotating parts. Common types include mechanical seals, lip seals, and O-rings.
4. Bearings:
– Bearings support the rotating shaft and ensure smooth and efficient rotation. They reduce friction and wear, extending the life of the rotary union.
5. Internal Passages:
– Channels within the pneumatic rotary union allow the gas to flow from the stationary side to the rotating side.

How pneumatic rotary union Works
1. Gas Entry:
– Compressed air or gas enters the stationary housing through an inlet port. This can be a pipe, hose, or other connection method.
2. Seal Interface:
– The gas passes through a seal interface. The seals are designed to maintain a tight, leak-free connection between the stationary and rotating parts. The seals must be able to withstand the pressure and temperature of the gas being transferred.
3. Rotation：
– The rotating shaft or drum is supported by bearings, which allow it to rotate smoothly. The bearings are typically designed to handle the specific load and speed requirements of the application.
4. Gas Transfer:
– The gas flows through internal passages in the rotary union. These passages are designed to direct the gas from the stationary side to the rotating side. The design of these passages ensures that the gas is transferred efficiently without significant pressure drop.
5. Exit:
– The gas exits the pneumatic rotary union through an outlet port on the rotating side. This port is connected to the rotating machinery, where the gas is used for various purposes such as actuation, cooling or cleaning.

The working process of the pneumatic rotary union
When the gas passes through the complex flow channel, it enters the airflow channel in the rotating part, the rotor begins to rotate ,the rotating angular speed is proportional to the pressure of the air source,  the greater the angular speed, the greater the load. The movement of the rotor will drive the pipe or tool attached to it to rotate. At the same time, the sealing ring above the stator can seal the joint and no air leakage occurs during the connection.

Key Features and Benefits of pneumatic rotary union
– High Precision: pneumatic rotary unions are precision-engineered to ensure minimal leakage and long service life.
– Durable Construction: Made from high-quality materials such as stainless steel, brass and other corrosion-resistant materials to withstand harsh environments.
– Multiple Channels: Some models can handle multiple gas lines simultaneously, allowing for the transfer of different gases or air streams.
– Wide Temperature and Pressure Range: Capable of operating under a wide range of temperatures and pressures, making them suitable for diverse industrial applications.
– Customization: Can be tailored to meet specific application needs, including different mounting styles and special material requirements.

Applications of pneumatic rotary union
– Machine Tools: For pneumatic tools and actuators that require compressed air while rotating.
– Automotive Manufacturing: For assembly lines where pneumatic tools and equipment need to rotate.
– Robotics: For robotic arms and other automated systems that require pneumatic power during rotation.
– Packaging Machinery: For packaging lines where pneumatic actuators and grippers need to operate while rotating.
– Aerospace and Defense: For pneumatic systems in aircraft and military vehicles.
– Textile Industry: For pneumatic controls in textile machinery.
– Food and Beverage: For pneumatic actuators and cleaning systems in food processing equipment.

The advantages and disadvantages of pneumatic rotary union
The pneumatic rotary union has the following advantages: ① it can realize dynamic connection, which can rotate and swing left and right; Light weight, simple structure, high reliability, long service life; ③ Suitable for equipment that is difficult to connect with cables, such as rotary tire production lines, CNC processing machines, etc.
Disadvantages, because the air source of the pneumatic rotary joint needs to maintain a certain pressure manually or automatically, when the air source pressure is unstable, the joint will not work normally. At the same time, there may be wear, leakage and other phenomena between the connections, which need to be repaired and replaced in time.

Maintenance and Care of pneumatic rotary union
– Regular Inspection: Check for leaks, wear, and damage.
– Lubrication: Ensure proper lubrication of seals and bearings.
– Cleaning: Keep the union and surrounding area clean to prevent contamination.
– Replacement of Worn Parts: Replace worn or damaged seals and bearings.
– Pressure Testing: Periodically test the union for leaks and proper function.

By understanding these components and how they work together, you can better appreciate the role of pneumatic rotary union in various industrial applications. If you have any specific questions or need further details, feel free to ask us.