What are the reasons for the failure of bolts and nuts?

1. Material problems, machining defects and heat treatment process problems can also cause connecting rod bolts to break during engine operation
2. When the diesel engine has a speeding failure or the piston burns to death in the cylinder during operation, the connecting rod bolt is pulled off. If the engine has a speeding failure during use, a comprehensive inspection of the engine should be carried out, and it is best to replace the connecting rod bolts; if there is a serious cylinder pull in individual cylinders during operation, the connecting rod should also be replaced when replacing the cylinder piston assembly. Bolt replacement.
3. The connecting rod of the diesel engine is divided into various grades. During the maintenance, it should be noted that the connecting rod of different grades cannot be replaced. If the connecting rod cover is messed up or wrongly installed due to carelessness during the maintenance, it will cause the joint surface of the connecting rod big end to not fit tightly, and the connecting rod cover will be loosened during the engine operation, resulting in the breakage of the connecting rod bolt.
4. The tightening torque is too large during assembly, and the force is uneven. Since there is no strict torque wrench in the assembly, the specific tightening torque is not well understood, and it is believed that the tighter the better; the connecting rod bolts are tightened with a longer afterburner rod, and the tightening torque is too large, exceeding the bolt material. The yield limit causes the connecting rod bolt to yield and deform, causing it to break due to excessive elongation under the action of the impact load. It should be emphasized that the connecting rod bolts must be tightened according to the standard. Never think that the tighter and the stronger the force, the better.