Ship Stern Tube White Metal Bearings

Ship stern tube white metal bearings

Category: Ship stern tube white metal bearings

Marking example:

• Basic shaft diameter Φ 200mm, length 500mm, gauge tube rear Bearing WHA200×500

• Basic shaft diameter Φ196mm, length 300mm, gauge tube front Bearing WQA196×300

The white alloy bearing of the ship stern tube is usually also called Babbitt alloy bearing.  The following is a detailed introduction:

Structural features

• Double-layer structure: generally composed of a shell and a white alloy layer of the lining.  The shell material is often copper alloy, cast iron or cast steel, providing overall strength and support.  The white alloy layer is the key wear-resistant and friction-reducing part, usually attached to the inner surface of the shell by casting or pouring.

• Lubrication groove: In order to ensure good lubrication effect, lubrication grooves of various shapes are usually designed on the inner surface of the bearing, such as axial, radial or spiral grooves.  These grooves can evenly distribute the lubricating oil on the contact surface between the bearing and the stern shaft, improve lubrication performance, and reduce friction and wear.

• Sealing structure: Sealing devices such as sealing rings and sealing rings will be equipped at both ends of the bearing or at the joint with the stern shaft to prevent lubricating oil leakage and ensure that the bearing works in a good lubrication environment.

Working principle

• Oil film lubrication principle: When the ship's stern shaft rotates in the white metal bearing, the lubricating oil will form an oil film in the gap between the stern shaft and the bearing.  This oil film separates the stern shaft from the white metal bearing, so that the friction between the two is transformed from direct metal contact friction to liquid friction inside the oil film, thereby greatly reducing the friction coefficient and reducing wear.

• Load-bearing principle: White metal has good compressive strength and hardness, and has sufficient fatigue strength and load-bearing capacity.  When the load generated by the propeller and other components of the ship is transmitted to the white metal bearing through the stern shaft, the bearing can rely on its own material properties and structural characteristics to evenly distribute the load on the bearing surface, bear and transmit these loads, and ensure the stable operation of the stern shaft.

• Heat dissipation principle: During the operation of the bearing, a certain amount of heat will be generated due to friction.  White metal has good thermal conductivity, which can quickly transfer the heat generated by friction to the outer shell of the bearing, and then transfer it to the surrounding medium (such as seawater or lubricating oil) through the outer shell, thereby effectively dissipating heat and keeping the temperature of the bearing within the normal range.

Application advantages

• Good wear resistance and anti-friction: The composition characteristics of white alloy enable it to effectively resist wear in the relative movement with the stern shaft, maintain the dimensional accuracy and performance stability of the bearing, and extend the service life of the bearing and the stern shaft.

• Good running-in and anti-bite: After the new bearing is installed or the stern shaft is replaced, the white alloy bearing can quickly run-in with the stern shaft surface to form a good match.  At the same time, it is not easy to bite with the stern shaft during operation, and it can better protect the stern shaft and the bearing itself even in the case of short-term poor lubrication or overload.

• Good corrosion resistance: For the corrosive environment such as seawater where the ship is located, white alloy has a certain corrosion resistance, can maintain performance in long-term use, and is not easily damaged by corrosion.

• Good compliance and embedding: White alloy can adapt to the slight deformation and misalignment of the stern shaft within a certain range, and ensure good contact with the stern shaft through its own elastic deformation.  At the same time, it has a certain embedding ability for tiny impurity particles that enter the bearing gap, so as to prevent these impurities from scratching the bearing and stern shaft.

Scope of application

• Large ocean-going ships: such as bulk carriers, tankers, container ships, etc., these ships have large stern shaft diameters and bear large loads.  White alloy bearings can meet the use requirements of ships in long-term ocean voyages with their high load-bearing capacity and good performance.

• High-speed ships: such as passenger ro-ro ships, high-speed yachts, etc., have high requirements for the speed and stability of bearings.  The low friction coefficient and good heat dissipation performance of white alloy bearings can ensure stable operation at high-speed rotation and reduce energy loss and wear.

• Ships with high stability requirements: such as marine engineering ships, scientific research ships, etc., have extremely high requirements for the stability of the ship's propulsion system during operation.  The good performance of white alloy bearings can provide guarantees for the safe and stable operation of ships.