In the process of fully automatic CNC lathe machining, loose workpiece clamping is a key hidden danger that can easily cause quality accidents and equipment damage. It may lead to workpiece size deviation, surface scratches, and even safety accidents such as workpiece flying off and tool breakage in severe cases. Therefore, accurately controlling the key points of the clamping process and establishing a full process prevention mechanism are of great significance for ensuring processing stability.

The root causes of loose workpiece clamping can be attributed to three major categories: unreasonable clamping system design, non-standard operation, and abnormal equipment status. In terms of clamping systems, insufficient fixture selection and workpiece compatibility are the primary issues. For example, when using rigid chucks to clamp thin-walled workpieces, uneven clamping force distribution can easily lead to clamping failure; At the same time, the wear of key components of the fixture and the decrease in positioning surface accuracy will also reduce the clamping stability. At the operational level, improper setting of clamping force parameters is common. If the clamping force parameter is too large, it can easily cause deformation of the workpiece, while if it is too small, it can directly lead to loosening. However, if the positioning surface of the workpiece is not cleaned properly before clamping, residual impurities such as iron filings and oil stains can damage the positioning accuracy and indirectly cause loosening. At the equipment level, equipment problems such as unstable pressure of the chuck power source and excessive clearance between the pull rods can cause the clamping force to be unable to remain constant, leading to loosening faults.

To address the above root causes, a prevention system needs to be constructed from three dimensions: design, operation, and maintenance. In the design phase, it is necessary to do a good job in fixture compatibility design, and select appropriate fixture types based on the material and structure of the workpiece. For example, for thin-walled parts, elastic chucks or specialized soft claws should be used to ensure uniform clamping force; Simultaneously optimize the positioning structure and adopt reliable positioning methods such as "one side, two pins" to reduce positioning errors. The operation process should be standardized, and the workpiece positioning surface and fixture positioning surface should be cleaned before clamping to remove impurities; Strictly set the clamping force parameters according to the process documents, and verify stability through trial cutting after the first clamping. In terms of maintenance, a regular inspection mechanism should be established to check the air or oil pressure of the chuck before starting up every day, inspect the wear of the fixture every week, calibrate the accuracy of key components such as the chuck rod and gripper every month, and replace worn parts in a timely manner.

In addition, digital means can be used to improve the prevention effect. By installing force sensors on the fixture, real-time monitoring of clamping force changes can be carried out, and an alarm can be immediately triggered once the threshold is exceeded. In short, the prevention of workpiece clamping looseness in fully automatic CNC lathes needs to adhere to the principles of "source control, process standardization, and regular maintenance", and integrate preventive measures into the entire processing process in order to effectively avoid the risk of failure.