How to solve the CNC machining accuracy problem of aluminum cavity?

In order to ensure the quality of the workpiece, many processing manufacturers must ensure the machining accuracy during the CNC machining of the aluminum cavity. Then, from which aspects should the reasons for the machining accuracy be analyzed?

1. The size of the workpiece is accurate, and the surface finish is poor

The cause of the failure: the tool tip is damaged and not sharp; the machine tool resonates and the placement is not stable; the machine tool has crawling phenomenon; the processing technology is not good.

Solution: After the tool is worn or damaged, it is not sharp, then re-sharpening or selecting a better tool to re-calibrate the tool; the machine has resonance or is not stable, adjust the level, lay the foundation, and fix it smoothly; the cause of mechanical crawling is drag The plate guide rail is severely worn, the ball screw is worn or loose, the machine tool should be maintained, and the iron wire should be cleaned after get off work, and lubricated in time to reduce friction; choose a coolant suitable for workpiece processing, if it can meet the processing requirements of other processes In this case, try to choose a higher spindle speed.

2. The phenomenon of taper and small head on the workpiece

The cause of the failure: the level of the machine is not adjusted properly, one high and one low, resulting in uneven placement; when turning the long axis, the contribution material is harder, and the tool eats deeper, causing the tool to give way; the tailstock thimble is not concentric with the spindle.

Solution: Use a level to adjust the level of the machine tool, lay a solid foundation, and fix the machine tool to improve its toughness; choose a reasonable process and appropriate cutting feed to avoid the tool being forced to give it to the knife; adjust the tailstock.

3. The effect of machining arc is not ideal, and the size is not in place

The cause of the failure: the overlap of the vibration frequency causes resonance; the processing technology; the parameter setting is unreasonable, the feed speed is too large, and the arc processing is out of step; the looseness caused by the large screw gap or the out of step caused by the screw is too tight; the timing belt Wear.

Solution: Find out the resonant parts, change their frequency to avoid resonance; consider the processing technology of the workpiece material, and make a reasonable program; for the stepper motor, the processing rate F cannot be set too large; whether the machine is installed firmly, placed smoothly, and dragged Whether the plate is too tight after being worn, the gap is increased or the tool holder is loose, etc.; replace the timing belt.

4. In the mass production, the workpiece is out of tolerance occasionally

Cause of failure: The tooling and fixture must be carefully checked, and the operator's operation method and the reliability of the clamping must be taken into account. Due to the size change caused by the clamping, the tooling must be improved so that the worker may try to avoid misjudgment by human negligence; the CNC system may When the external power supply fluctuates or is disturbed, it will automatically generate interference pulses, which will be transmitted to the drive to cause the drive to receive excess pulses to drive the motor to take away or drive the phenomenon.

Solution: Understand the law, try to use some anti-interference measures, such as: isolation of strong electric cables with strong electric field interference from signal lines of weak electric signals, adding anti-interference absorption capacitance and shielding wire isolation, in addition, check the ground wire Whether the connection is firm and the grounding contact is nearest, take all anti-interference measures to avoid system interference.