Repair process for partial damage and welding of sliding bearings
Wujin, also known as Babbitt alloy, is composed of a soft matrix (tin, lead) and hard points embedded within the matrix. When used as a sliding bearing, the soft substrate will wear down quickly and become concave, while the hard points are used to support the load of the shaft. It is divided into two types: tin based and lead based. Tin based alloys contain over 80% tin, while lead based alloys contain over 70% lead. The bearings of rotating machinery in thermal power plants are mainly made of tin based Babbitt alloy, such as CuSnSb11-6, which is mainly composed of 83% tin (Sn), 10-12% antimony (Sb), 5.5-6.5% copper (Cu), and has a hardness not less than HB27.
Repair welding process for local wear of bearing
The bearing shell is usually manufactured by pouring, and during repair welding, an oxygen acetylene flame can be used to tightly weld the black gold together.
1. Preparation before welding
⑴ Making black gold bars: Use angle steel as a mold, and use an oxygen acetylene flame to melt the black gold into 8-10mm thick strips as welding wire for easy welding.
⑵ Cleaning: Clean the black gold at the welding repair site with alcohol, propanol and other reagents to remove the oil stains in the pores of the tile surface and expose the metallic luster.
⑶ Selection of welding torch: Different types of welding torches are selected according to the size of the bearing shell. Generally, H01-6 is chosen, and micro welding torches can be used for extra small bearing.
2. Operation
(1) Heat the repaired welding surface with a small carbonization flame, and continuously rub the heated area with a solder rod until the solder melts and adheres to the bearing body. Black gold strips can be used for repairing the bearing shell. The surface of the repaired welding can be heated with a carbide flame. When the surface of the bearing shell melts, black gold strips can be added immediately while melting the base material and continuously moving forward. The operation should be quick and agile to prevent the black gold from overheating and causing the tile bottom to fall off. Due to the fact that Wujin does not change color when heated, it is necessary to observe the state of the flame pool and grasp the temperature of the bearing shell during operation. When a depression is found, it indicates that the temperature is too high, and the flame should be quickly transferred to a lower temperature area for welding repair. If the welding area is large, it is advisable to divide it into several small pieces and alternately melt the black gold material to avoid continuous welding in one part. The thickness of each layer of weld overlay should not be too large. If the thickness of one layer of weld overlay does not meet the requirements, another layer can be stacked.
Preventing overheating of the black gold material during the welding process is the key and difficult point of the operation process. This is because high temperature can cause the black gold to become brittle, which may crack and cause detachment at the bottom joint. After welding, it is necessary to carefully inspect the welding area for defects such as detachment, inclusions, and pores. Only after passing the inspection can processing be carried out.
2026 January 3rd Week Marginal Product Recommendation:
MG-1A Aluminum matrix composite bearings：
MG-1A is a composite material of PTFE compound tape on aluminum shell, the PTFE is tape up to 0.20 mm thickness, enabling the bearing can be sized after being fixed, meanwhile the thick PTFE layer isolates noise. The bearing is widely applied in OA machinery, shock absorber for light design bicycle.
