Nine Reasons For The Instability Of CNC Machined Parts (1)

Sep. 25, 2021


In order to ensure the quality of your CNC machined parts and increase profits, please read the following information carefully.


1. Batch production, occasionally present CNC machining parts super poor

Reason: It is necessary to check the fixture carefully, taking into account the operator's operation method and the reliability of the clamping. Because of the scale changes caused by clamping, it is necessary to improve the tooling so that workers try to prevent human negligence to make misjudgment phenomenon. The CNC system may be subject to fluctuations in the external power supply or disturbed by the active generation of disturbance pulses. Pass to the drive resulting in the drive to accept the remaining pulse drive motor to take away or less away phenomenon.

Solution: understand the rules, try to use some anti-disturbance methods, such as strong electric field disturbance of the strong cable and weak signal line blocking, participate in the anti-disturbance absorption capacitor, and the use of shielded line blocking. In addition, check whether the ground is connected solidly, ground contact recently, adopt all anti-disturbance methods to prevent the system from being disturbed.


2. CNC machining parts occur taper size head phenomenon

Reason: the level of machine tool placement is not well adjusted, a high and a low, the occurrence of unstable placement. When turning long axis, dedication material is relatively hard, the tool eats deeper, the formation of the tool let phenomenon. The tailstock ejector pin and spindle are not the same center.

Solution: Use a level to adjust the level of the machine tool. Lay a thick foundation to fix the machine tool. Improve its resistance. Select a reasonable process and proper cutting feed to prevent the tool from letting out by force. Adjust the tailstock.


3. Drive phase light normal, CNC machining parts scale when large when small

Reason: machine tool dragging plate long time high-speed operation, resulting in screw and bearing wear. Repeat positioning accuracy of the tool holder in the long time use of error. Each time the drag plate can accurately return to the starting point of processing, but the scale of the workpiece is still changing. This phenomenon is usually caused by the spindle. The high-speed rolling of the spindle makes the bearings wear out severely and causes the machining scale to change. Metal processing micro letter, the content is good, worthy of attention.

Solution: Use the percentage table against the bottom of the tool holder, together with the system to amend a fixed cycle program. Check the repeat positioning accuracy of the dragging plate and adjust the screw clearance. Replace the bearing; check the repeat positioning accuracy of the tool holder with a percentage table. Adjust the machine or replace the tool holder. Check the accuracy of returning to the starting point of the program after machining the workpiece with a percentage meter. If you can, repair the spindle and replace the bearings.



4. CNC machining parts processing scale is not in place

Reason: The overlap of vibration frequency leads to resonance. The parameter setting is not reasonable, the feed speed is too large so that the circular arc processing is out of step. The looseness caused by the large clearance of the screw or the loss of step caused by the over-tightening of the screw, synchronous belt wear.

Solution: Find out the resonant parts and change their frequency to prevent resonance. Consider the processing process of workpiece material. Reasonable preparation of the program. Whether the machine is solidly installed and smoothly placed. Whether the dragging plate is too tight after wear, the gap increases or the tool holder is loose, etc.


5. The system caused by the unstable scale change of CNC machining parts

Causes: system parameters set unreasonably. The operating voltage is unstable. The system is disturbed by external disturbance, resulting in the system being out of step. The capacitor has been added, but the impedance between the system and the driver does not match. Resulting in the loss of useful signals. Signal transmission between the system and the driver is not normal. The system is damaged or internal fault.

Solution: Speed, whether the acceleration time is too large. Spindle speed, cutting speed is reasonable. Whether the operator's parameter correction leads to system function changes; add voltage stabilization equipment. Connect the ground wire and make sure it is firmly connected. Add anti-disturbance absorption capacitor at the pulse output contact of the driver. Select the appropriate type of capacitor. Check whether the signal connection line between the system and the driver is shielded and whether the connection is secure. Check whether the system pulse generation signal is lost or added. Send the factory repair or replace the motherboard.


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