There may be many reasons why the CNC vertical lathe spindle heats up:

1. Overload operation: When the main bearing of the CNC vertical lathe is subjected to a large load or continues to operate for too long, the heat generated by friction will cause the main shaft to heat up. This usually occurs when machining heavy, hard materials or when machining continuously for long periods of time.

2. Cutting heat: During the high-speed cutting process of CNC vertical lathe, a large amount of heat will be generated when the tool contacts the workpiece, and this heat will also be conducted to the spindle, causing the spindle temperature to rise. In CNC vertical lathes, especially in the case of high-speed cutting, high feed speed or large cutting depth, the temperature of the spindle increases more significantly.

3. Insufficient lubrication: If the CNC vertical lathe lubrication system fails or there is insufficient lubricating oil, the friction of the spindle bearing will increase, thereby generating more heat and causing the spindle to heat up.

4. Poor spindle heat dissipation: If the spindle heat dissipation design of the CNC vertical lathe is poor or the cooling system fails, the heat cannot be dissipated in time, which will also cause the spindle to heat up.

5. Spindle bearing damage: If the CNC vertical lathe spindle bearing is damaged or severely worn, it will cause increased friction, which will generate more heat and cause the spindle to heat up.

6. The ambient temperature is too high: If the working environment temperature of the CNC vertical lathe is too high, it will also affect the heat dissipation effect of the CNC vertical lathe spindle, causing the spindle to heat up.

To avoid overheating of the spindle, the following measures can be taken:

1. The CNC vertical lathe reasonably controls the processing load to avoid overload operation;

2. CNC vertical lathe uses appropriate cutting parameters to minimize the generation of cutting heat;

3. Regularly inspect and maintain the lubrication system of CNC vertical lathes to ensure sufficient lubricating oil;

4. Ensure the normal operation of the cooling system of the CNC vertical lathe;

5. Regularly check the status of the CNC vertical lathe spindle bearings and replace seriously worn bearings in a timely manner;

6. Control the working environment temperature of the CNC vertical lathe to avoid excessive ambient temperature affecting the heat dissipation effect of the spindle.