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Product Description
Sliding bearings are important support components for the intermediate shaft in ship propulsion systems. They are usually installed in the intermediate bearing seat and work in conjunction with the intermediate shaft, bearing bushings, and lubrication system to carry the radial load of the intermediate shaft and maintain the alignment accuracy of the shaft system.
White Metal Sliding Bearing is a type of hydrodynamic plain bearing also widely used in industrial rotating machinery. The term "white metal" refers to the soft, silver-colored bearing alloy—primarily composed of tin, lead, antimony, and copper—that forms the sliding surface of the bearing. White metal bearings are particularly suitable for applications requiring high load capacity, smooth running, and operational safety. They excel in large-scale, low-to-medium speed, heavy-load operating conditions, serving as critical components that ensure the safe and stable operation of key industrial equipment.
In the propulsion system of a ship, the intermediate shaft connects the thrust shaft and propeller shaft, and its operational stability directly affects the reliability and power transmission efficiency of the entire propulsion shaft system. As the direct working support surface of the intermediate shaft, sliding bearings have high requirements for dimensional accuracy, surface quality, and material wear resistance. Our company can customize the design and processing of sliding bearings according to different ship types, shaft diameters, and load conditions to meet the needs of long-term continuous operation and complex sea conditions.
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System level Product Extension Description/Ship Propulsion System
In the ship propulsion system, Sliding Bearing is the core, and the intermediate shaft bearing system, thrust bearings, thrust shafts, propeller shafts, and other components together form a complete propulsion shaft system. During the operation of the ship, the thrust generated by the propeller is transmitted step by step through the propeller shaft, intermediate shaft, and thrust shaft, while the intermediate shaft sliding bearings and related lubrication systems continue to provide stable support for the shaft system, ensuring a smooth and reliable power transmission process.
Our company can provide manufacturing and matching capabilities for various key components of ship propulsion systems, including intermediate shafts, bearing bushings, thrust shafts, thrust bearing components, propeller shaft assemblies, and related bearing structural components, focusing on Sliding Bearing and intermediate shaft bearing systems. By precise matching between key components and highly reliable manufacturing, we assist customers in building stable and controllable ship propulsion systems, achieving a comprehensive solution from individual components to the entire propulsion shaft system.
Machining Process
Babbitting is the process of bonding a relatively soft white metal (babbitt alloy) to a stronger backing material—typically mild steel, cast iron, or bronze—which supports the weight and torsion of a rotating or sliding shaft. The babbitt, being softer than the shaft and possessing excellent anti-frictional qualities, prevents galling and scoring of the shaft over long periods of use.
The manufacturing process can be systematically divided into: Steel Backing Preparation → Surface Cleaning → Tinning → Babbitt Casting → Rough Machining → Finish Machining → Inspection.
Rough machine (turning/milling) to remove burrs and scale
Heat treatment: ~700°C for 5–6 hours to relieve stress, then slow cool to room temperature
Grind inner surface to remove oxide layer
Chemically clean (e.g., saturated ZnCl₂ solution) to remove oil and contaminants
Preheat to ~200°C (45 min to 4 hours depending on shell size)
Tinning: Immerse in molten tin bath with NH₄Cl/ZnCl₂ flux to form a uniform tin coating – critical for bond strength
4. Babbitt Casting
Centrifugal casting is most common for high-quality industrial bearings because of the key feature like dense structure, strong bond, no porosity
Controlled cooling (air or water mist)
Rough turn/bore to remove excess material, leaving ~0.75–1.0 inch (19–25 mm) stock for finishing
Precision boring to final diameter
Honing / polishing: target surface finish Ra ≤ 0.8 μm
Use sharp, high-positive-rake tools (HSS or polished aluminum-grade inserts) to avoid tearing or smearing
Visual: No cracks, porosity, or inclusions
Dimensional: Bore diameter, wall thickness, roundness, straightness
Non-destructive testing: Ultrasonic (UT) for bond integrity; dye penetrant (PT) for surface defects
Bond strength: Failure must occur within the babbitt layer, not at the babbitt-steel interface
Product Inspection
After completing the main processing, the sliding bearings will undergo strict quality inspection. This mainly includes measurement of size and fitting accuracy, inspection of surface defects, and PT testing (penetration testing) to ensure that there are no micro cracks or processing defects inside and on the surface, ensuring long-term reliability during operation.
The picture shows the PT inspection site for sliding bearings, ensuring that each bearing meets high standard quality requirements before delivery.
Relying on mature processing technology and testing system, our company's sliding bearings can meet the usage needs of ship propulsion systems under high load, long-term operation, and complex working conditions. At the same time, they support processing according to drawings or customized manufacturing.
PT
PT
Packaging & Shipping
1. Inner Protective Layer
All critical surfaces of the product (such as machined surfaces, mating surfaces, end faces, etc.) are coated with anti-rust oil or suitable protective agents and wrapped with VCI (Volatile Corrosion Inhibitor) paper or other protective materials. This effectively isolates air and moisture, preventing corrosion or damage during transportation and storage.
2. Cushioning and Fixation Layer
Cushioning materials (such as pearl cotton, foam, or rubber pads) are applied around the product to provide full protection. Customized supports or positioning blocks are also used inside the packaging case to prevent rolling or displacement of the product, ensuring stability during transport.
3. Outer Reinforced Packaging
The outer layer uses a reinforced export wooden case or other sturdy packaging with strong structural integrity and high load-bearing capacity, suitable for sea, land, or air transport. Handling marks such as center of gravity, lifting points, moisture protection, and anti-tilt symbols can be applied according to customer requirements, facilitating on-site handling and identification.
4. Customized Packaging Options
Packaging solutions can be customized according to customer requirements, including protection grade, cushioning method, fixing structure, and outer case design, to meet different transportation conditions, destination ports, and project site requirements.
