Causes and Solutions of CNC Machining Faults
The machining arc effect of CNC machining workpiece is not ideal, and the size is not in place. The reason is that resonance is caused by the overlapping of vibration frequency; processing technology; unreasonable parameter setting and high feed speed make arc processing out of sync; excessive screw clearance leads to loosening Or the screw is too tight to cause out of step; the timing belt is worn out. Solution: Find out the parts that resonate, change their frequency, and avoid resonance. Consider the processing technology of the workpiece material and program reasonably; for stepping motors, the processing speed f cannot be set too high; whether the machine tool is installed firmly, whether the placement is stable, whether the tool holder is too tight after wear, whether the gap increases, and whether the tool holder is loose wait. Replace timing belt.
The reason for the large taper phenomenon of CNC machining workpieces is that the placement level of the machine tool has not been adjusted, one high and one low, resulting in uneven placement; when the long axis is turned, the material produced is relatively hard, and the cutting tool eats deeper, resulting in tool yielding . The tailstock thimble is not concentric with the main shaft. Solution: Use a level to adjust the level of the machine tool, lay a good foundation, fix the machine tool, and improve the toughness of the machine tool. Choose a reasonable process and appropriate cutting feed to prevent the tool from being forced to yield. Adjust the tailstock.
The phase light of the CNC machining driver is normal, but the size of the workpiece to be processed varies. The reason is that the long-term high-speed operation of the tool holder of the machine tool causes the wear of the screw and the bearing. The repeated positioning accuracy of the tool holder will deviate during long-term use. The carriage can return to the machining starting point precisely every time, but the dimensions of the machining workpiece will still change. This phenomenon is usually caused by the spindle. The high-speed rotation of the spindle causes serious bearing wear, resulting in changes in the machining dimensions. Solution: Use a dial gauge to lean against the bottom of the tool holder, edit a fixed cycle program through the system, check the repeat positioning accuracy of the tool holder, adjust the screw clearance, and replace the bearing. Use a dial indicator to check the repeated positioning accuracy of the tool holder, adjust the machine or replace the tool holder; the dial indicator is used to check whether the processed workpiece is accurately returned to the starting point of the program. Overhaul the spindle and replace the bearings, if possible.
The reason why CNC machining workpieces are accurate in size and poor in surface finish is because the tool tip is damaged and not sharp. The machine tool resonates and is not placed stably. The machine tool is crawling; the processing technology is not good. Solution: If the knives are worn or damaged and not sharp, re-sharpen the knives or choose a better one to realign the knives. If the machine tool resonates or is not placed stably, adjust the level, lay a good foundation and fix it stably. The reason for the crawling of the machine is that the carriage rails are severely worn, and the balls are worn or loose. Machine tools should be maintained with care. After commuting, the iron wire should be cleaned and lubricated in time to reduce friction. Choose a coolant suitable for workpiece processing, and try to choose a higher spindle speed when it can meet the processing requirements of other processes.
