Coolant-Through Rotary Joints in Machining Centers
On machining centers equipped with coolant-through spindle functionality, a rotary joint mounted at the spindle rear feeds high-pressure cutting fluid from stationary piping into the rotating spindle core, then through the internal coolant channels of the tool to the cutting zone. The core engineering challenge is that higher coolant pressure increases the load on seals and bearings, while higher spindle speed makes balance and temperature control more demanding. Pressure, speed and bore size must therefore be evaluated together rather than one at a time.
Working Conditions and Pressure Ratings
Typical coolant-through systems operate between 2 and 7 MPa, while deep-hole drilling and difficult-to-machine materials may require more than 10 MPa. DEWEL coolant-through rotary joints cover the standard pressure range, and the high-pressure series reaches up to 138 MPa with bore sizes from DN6 to DN350. Speed must be checked against the maximum spindle speed because the joint rotates with the spindle; series models support up to 30,000 RPM depending on the specification.
Sealing Design and Media
Water-based cutting fluid contains additives and fine chip particles that cause abrasive wear on sealing faces. Wear-resistant sealing pairs are recommended, together with coolant filtration of appropriate fineness to reduce early seal damage. When a single spindle requires both coolant supply and hydraulic control, a double-circuit design keeps the two media channels independent and prevents pressure interaction.
Installation and Maintenance
Maintain coaxiality between the joint and the spindle to avoid radial loads on the internal bearings, and use flexible hose connections to limit assembly stress on the housing. Routine maintenance focuses on seal leakage and bearing temperature; replace seals promptly once leakage appears. DEWEL was established in 2006 in Tengzhou, Shandong, manufactures under ISO 9001, and offers custom designs based on customer spindle drawings, including interface dimensions, speed and pressure requirements.
Summary
When requesting a proposal, provide the medium and working pressure, maximum spindle speed, bore size and flow requirements, and mounting dimensions. Product details are available on the coolant-through rotary joint and high-pressure rotary joint pages, and specific working conditions can be discussed for custom solutions.
