How Henan Huachuang Metal Materials Trading Co., Ltd. Repairs Babbitt Tin-Based Alloy Bearing Bush and Sleeve. Bearing seizure causes operational equipment shutdown due to damage to the Babbitt alloy bearing bush caused by operational vibrations, wear, and other factors. In severely damaged bearing bushes, the damaged area accounts for up to one-third of the total surface, with localized separation between the bearing bush and its housing. Therefore, it was decided to use oxy-acetylene welding to repair the damaged Babbitt alloy bearing bush.
I.1. Requirements for Welding Repair of the Bearing Bush
The weld bead must be free of pores, slag inclusions, and lack of fusion. Due to the heavy weight and high speed (3000 rpm) of the equipment rotor, the bearing bush must maintain good lubrication with the rotor shaft working surface. Additionally, the strength of the brazed Babbitt alloy bearing bush must be ensured to withstand the shear stress generated during rotation.
2. The surface of the repaired weld bead must restore the original dimensions.
II. Pre-Welding Preparation
1. Preparation of Welding Wire
Using an oxy-acetylene flame as the heat source, the welding wire is self-melted. The bearing bush material is Babbitt alloy type ZchSnSb11-6, a soft metal with a very low melting point (240°C). The selected welding wire is the same material as the bearing bush. As shown in Figure 2, after melting the welding wire, use a knife to remove edges, eliminate surface oxide films and slag pores. Do not use sandpaper or a grinding wheel for surface treatment of the welding wire.
2. Surface Treatment of the Bearing Bush
Oil molecules have penetrated deeply into the substrate. For bearing bushes that have been operating in lubricating oil conditions for an extended period, these oil-impregnated surface layers hinder metal fusion during welding repair and must be thoroughly cleaned.
Conduct a detailed inspection of the damaged bearing bush to identify the areas requiring repair. Then, place the bearing bush in a drying oven and heat it to 150-180°C. After completely removing the unmelted but overheated areas, use commercially available metal cleaning agents to thoroughly clean the surface oxide films and oil stains. Next, use a knife to scrape the repair area by 0.2-0.5 mm. The treated bearing bush should undergo welding repair immediately.
III. Welding Repair Process of the Bearing Bush
1. Preheating
If the temperature of the bearing alloy drops too much, use a welding torch model H01-61 with a No. 61 nozzle. After surface treatment, heat the bearing bush to 150-180°C and place it on an electric furnace to slow down the cooling rate during welding repair. Care must be taken to avoid recontamination of the treated bearing bush surface.
2. Welding Repair Process Parameters
Welding speed: 58 cm/min; single weld bead width: 8-10 mm; thickness: 3-4 mm; apply 2-3 layers. Gas welding pressure: 0.02 MPa; neutral flame. Interlayer welding temperature must exceed 150°C. After cleaning the exposed areas of the bearing bush housing, begin brazing at the base layer first.