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【Abstract】 A new type of polymer composite material was used for on-site repair of the wear in the journal of the front main shaft and the damage to the supporting bearings in the JY002 type dryer； The causes of the failure and the advantages of on-site repairs were analyzed, and improvement measures to prevent equipment failures were proposed. 【Keywords】JY002 – On-site repair and prevention of wear in dryers 1. Equipment overview: The JY002 type dryer is a key piece of equipment in the alcoholysis process. The equipment housing consists of a cylinder (08) and side covers (05) on either side of it. The main shaft is composed of four solid short shafts and three hollow long shafts connected together via flanges. The four solid short shafts (03) are supported by their respective bearing seats (two inside the cylinder and two outside). The main shaft passes through the large covers on both sides of the cylinder along its central axis, and it performs circular motion driven by a chain attached to the solid short shaft at the front end (03). The radial arms on the main shaft are connected to scoops that transport the material entering the upper part of the front end of the cylinder, to the discharge outlet at the bottom of the rear end of the cylinder, while simultaneously mixing and drying it. A schematic diagram of the equipment structure is shown in Figure 1. 2 Fault symptoms and cause analysis: The equipment failure is caused by damage to bearing (11) at the solid short shaft at the input end, with irregular wear on the shaft journal of approximately 3–6 mm. The reason is that the inner ring of the bearing rubbed dry against the spindle for a long time, until the inner ring broke and got stuck on the shaft. Opening the upper cover of the bearing housing, the bearing is shiny with no residue of lubricant, indicating a lack of oil. The oil filling port on the upper bearing cover is located in the center of the outer ring of the bearing; there are no oil channels leading to either side inside. Once the grease enters through the filling port, it can only flow into the bearing via the oil channels and holes provided in the bearing itself. This type of oil filling port can only be used with bearings that have lubrication grooves and oil holes in the centered position of the outer ring. 3 On-site repair of faults 3.1 Fault diagnosis and repair methods 1) Traditional repair method: To repair this equipment, it is necessary to replace the bearings and also repair the spindle journal area. Traditional repair methods require removing the sprocket (02) at the shaft end as well as the bearing (11); separating the damaged solid shaft (03) from the hollow long shaft (9) at the flange connection (07); taking the solid short shaft out of the housing; performing weld repairs and machining to restore it to the dimensions specified in the drawings; and then reinstalling it. The sprockets and bearings on the solid shaft are removed using special pliers. The main difficulty in removing a solid short shaft for maintenance lies in finding a suitable method to take the shaft in question out of the dryer cylinder. The flange (07) of the solid shaft has a diameter larger than that of the inner hole of the packing seat (04) on the side cover; there is only one way to remove the damaged solid shaft from inside the equipment cylinder: by removing the side cover (05) at the front end of the cylinder. Once the side cover is separated from the equipment cylinder (08), the solid shaft (03) can be pulled out from behind. There are the following disadvantages to separating the side cover of the cylinder from the cylinder itself: limited working space on site and numerous pipelines in the vicinity ； No dedicated lifting space was reserved during installation ； The bolts connecting the flange (06) are difficult to remove ； It is difficult to lift and place the side cover ； The time required for maintenance is too long; based on experience, it takes 3 days to complete the disassembly, 3 days for the machining phase, and 3 days for the installation and restoration phase, for a total of 9 days. 2) Advantages and feasibility analysis of on-site repair: On-site repair is a maintenance method that has emerged in recent years. Its principle is to use polymer composite repair techniques to carry out repairs on-site, without removing the damaged equipment or components. The intermolecular forces resulting from the penetration of polymer materials in the repair composite ensure excellent adhesion to the repaired components, meeting the requirements for the equipment to withstand various combined forces during operation. Among such repair materials, Fushilan 2211F offers relatively reliable performance. The problems with traditional repair equipment cannot be resolved quickly and effectively on-site; significant time is wasted during the disassembly and reinstallation processes. Common repair methods such as welding, plating, and spraying require more time compared to using polymer-based repair materials for on-site repairs. On-site repair saves time through the three steps of dismantling, repairing, and installing. The overall costs associated with traditional maintenance, such as labor expenses, equipment transportation, and machining costs, are higher than those of on-site repair. Additionally, on-site repair is limited by space constraints, but it offers higher precision. The precision of on-site repair is ensured through several steps: positioning based on the dimensions of the reference plane (front and rear shoulders), repairing the worn areas, and ensuring the concentricity of the repaired areas ； Rely on release agents and the inner surface of specialized molds to ensure the smoothness of the repaired area ； Rely on heat assembly of the bearing to ensure an interference fit between the material and the bearing ； The good performance of the material is ensured by its inherent properties such as compressive strength, bending resistance, ductility, and temperature resistance. The shaft to be repaired rotates at a low speed (about 18 revolutions per minute), and the precision requirements are not high, making it suitable for on-site repair. From the perspective of saving maintenance time and similar factors, on-site repair should also be given priority. 3.2 On-site repair construction process 1) Clean the surface to be repaired and the reference surface, using alcohol or other organic solvents to remove oils, iron shavings, and other contaminants, so as to reveal the true color of the equipment material. Ensure molecular-level adhesion to the repair materials. 2) Prepare the composite material Fosblue 2211F and apply it to the worn areas that need repair. When applying, it should be done evenly and densely, without any visibly visible pores. After application, the diameter at the smallest area is about 4 mm larger than the standard diameter. 3) Machine the mold based on the reference surfaces of the shaft shoulders before and after the bearing location. Immediately after applying the material, install the clamping mold; the excess material is extruded through the discharge port. Once it has cured, open the mold to complete the repair and shaping process. The mold for repairing the worn areas of the bearing is shown in Figure 2. 4) After the repair is completed. The composite material coated with the wear-resistant layer can be left to cure naturally for 24 hours (the curing time can be reduced by baking), after which subsequent components such as bearings and sprockets can be installed. 5) Maintenance completed; trial operation with feeding started. It took 2 days to carry out the on-site repair of the worn area this time. 4 Improvement measures: The maintenance work required to replace the bearings in the JY002 type dryer is time-consuming. To completely resolve the problems caused by design flaws in the dryer’s bearing housings, which lead to poor lubrication and subsequent bearing damage and equipment failures, action can be taken from two aspects: one is to add oil guide channels to the upper cover of the bearing housing, so that after grease is injected through the filling port, it can flow through these channels and reach the inside of the bearings from both sides ； Second, it is necessary to refuel regularly (for example, every 3 months) and open the upper bearing cover for inspection. 5. The comprehensive repair on-site of the wear of the front spindle journal and the damage to the supporting bearings in the JY002 type dryer represents a useful attempt at applying a new maintenance concept. Compared to traditional maintenance, it eliminates the disassembly and installation steps, saving 2/3 of the maintenance time ； After repair, the equipment has been operating for nearly 8 months without any issues, achieving results that meet the requirements of traditional repair methods. This repair technique can be applied to the maintenance of other devices as well. Authors: Yang Huifeng, Niu Na, Zhao Guobao (Shanxi Sanwei Group Co., Ltd., Hongtong, Shanxi, 041603)