Defect Repair Of Grey Iron Casting
Grey iron castings are commonly used for casting structural parts in many industrial equipment. According to their structural characteristics, defects are prone to occur during the process of grey iron casting.Moreover, the defects of grey iron castings are usually inevitable, so repairing these defects is an important part of producing high-quality products. This article will discuss the technical requirements and process principles of repairing defects of grey iron castings based on NJ 431-86.
Technical Requirements
In order to repair the casting defects of grey iron castings, the following technical requirements should be met according to NJ 431-86. First of all, the structure of the material should be sound, and the surface is clean and free of dirt, oil and other contaminants. Secondly, the size of the defect should be within the allowable range and the depth should not exceed 5mm. Thirdly, the casting temperature should not be lower than 500℃, and the surface temperature of the parts should not be lower than 350℃. Finally, the surface flatness of the necessary position should meet the design requirements.
Process Principles
In general, the repairing process of grey iron casting usually follows the following 5 steps. Firstly, the surface of the casted parts need to be ground to remove any roughness and damages to ensure a smooth surface. Secondly, the surface should be cleaned to get rid of any residual oil and dirt. Thirdly, the necessary welding position should be determined based on the defect size and location. Then, the welding material should be selected according to the material characteristics. Finally, the welding procedure should be smooth and the temperature should be controlled to ensure the weld appearance and structure of the material.
Conclusion
Defect repair of grey iron casting is an important task in the production of these products. Therefore, to ensure the quality of the casted parts, it is essential to meet the relevant technical requirements and follow the process principles. According to NJ 431-86, the defects should not exceed 5mm, the surface temperature should not be lower than 350℃, and the welding material must be chosen according to the material characteristics. In addition, the casting surface should be clean and grinded in the process, and the welding procedure should be carried out smoothly. Following all these steps can help to efficiently repair the defects of grey iron castings.
