How do I choose a rotary joint?

When selecting a rotary joint, we usually first inquire about the operating temperature. Currently, the heat-conducting oil rotary joints suitable for the market are generally used in equipment with mixed oil, and they can even operate at high temperatures up to around 400℃. Therefore, when selecting a model, we must clarify the actual operating temperature, and then find a product model that can meet or even exceed the operating temperature. This way, we don’t have to worry about rotary joint leakage due to temperature issues. Different temperatures require different sealing components. A high-temperature joint can handle low temperatures without any problem, but using a low-temperature joint for high-temperature applications can easily damage the sealing components.

Another parameter is pressure. Currently, the highest pressure in market applications is found in cutting machines used by steel mills and hydraulic presses used on ships, with pressures reaching up to 60-100 MPA. Ordinary rotary joints are unable to withstand such pressure. If ordinary models are used in high-pressure applications, high pressure will inevitably lead to seal rupture and air leakage. Therefore, we must be clear about the startup pressure and normal pressure of our equipment, so that we can recommend or choose the correct product.
The last point is about rotational speed. Actually, most rotary joints rely on bearings for rotation, and speeds of 100-200 revolutions per minute are generally achievable. We usually need to pay attention to the fact that high-speed conditions should be considered only after meeting the requirements of temperature and pressure. Currently, we control high speeds by using good bearings to meet the rotational speed requirements. Seals and high-temperature components are mostly interchangeable, but bearings have some special characteristics. Generally, high-speed rotary joints are mostly used to pass water medium with a small amount of gas, and water has a cooling effect. Therefore, we usually choose imported NSK bearings or domestic RB bearings, which can meet the requirements of high-speed rotation while preventing rusting of bearing steel caused by water erosion