What are the common causes and solutions for CNC lathe spindle failures?

Diagnosis and maintenance of CNC lathe spindle component failures
The CNC lathe spindle component is the main component that affects the machining accuracy of the machine tool. Its rotation accuracy affects the machining accuracy of the workpiece, its power and rotation speed affect the machining efficiency, and its automatic speed change, accurate stop and tool change affect the automation level of the lathe. Therefore, the spindle component is required to have high rotation accuracy, rigidity, vibration resistance, wear resistance and low temperature rise that are compatible with the working performance of this lathe. In terms of structure, the clamping of the tool and the workpiece, the configuration of the bearing, the adjustment of the bearing clearance and the lubrication and sealing must be well solved.

Mechanical failures and maintenance methods of the spindle part

NO	Fault content	Fault cause	Fault troubleshooting
1	Processing accuracy does not meet requirements	The machine tool is impacted during movement	Check all parts that affect the geometric accuracy of the machine tool, especially the guide rails, and readjust or repair them according to the factory accuracy requirements.
1	Processing accuracy does not meet requirements	The machine tool is not installed firmly, the installation accuracy is low or there are changes
2	Large cutting vibration	The connecting screws between the spindle box and the bed are loose	After restoring the accuracy, tighten the connecting screws
		The bearing preload is insufficient and the clearance is too large	Re-adjust and eliminate bearing clearance, but the preload should not be too large to avoid damaging the bearing
		Bearing scratches or damage	Tighten the nut to ensure the spindle accuracy
		The spindle and the box have an out-of-tolerance precision	Replace bearings
		Other factors	Check tool or cutting process problems
		The moving parts of the turret tool holder are loose or not clamped due to insufficient pressure.	Adjustment and repair
3	The spindle is noisy	The dynamic balance of the spindle components is not good	Redo dynamic balance
		The gears are seriously damaged	Repair tooth surface damage
		The gear meshing clearance is large	Adjust or replace gears
		The bearings are rough or damaged	Replace bearings
		The transmission belt size is inconsistent or the belt is loose and unevenly stressed	Adjust or replace belts, do not mix old and new ones
		Poor gear accuracy	Replace gears
		Poor lubrication	Adjust lubricant volume, keep spindle box clean
4	Gear and bearing damage	The shifting pressure is too large and the gears are damaged by impact.	Adjust to appropriate pressure and flow according to the hydraulic principle diagram
		The gearshift mechanism is damaged or the fixing pin falls off	Repair or replace parts
		The bearing preload is too large or there is no lubrication	Re-adjust preload and ensure adequate lubrication
5	No spindle speed change	Is the electrical shift signal output?	Electrical personnel check and handle
		Is the pressure sufficient?	Check the working pressure, if it is lower than the rated pressure, adjust it
		The shift cylinder is worn or stuck.	Remove burrs and grinding scratches, clean and reinstall
		The shift solenoid valve is stuck.	Inspect and clean the solenoid valve
		The shift cylinder fork is off.	Repair or replace
		The shift cylinder is leaking oil or leaking internally.	Replace the sealing ring
		The shift compound switch is malfunctioning.	Replace a new switch
6	Spindle does not rotate	Is there any output of the electrical spindle rotation command?	Electrical personnel check and handle
		The protection switch is not pressed and causes failure	Inspect or replace the pressure-fit protection switch
		The chuck does not clamp the workpiece	Adjust or repair the chuck
		The shift compound switch is damaged	Replace the composite switch
		The shift solenoid valve is leaking	Replace the solenoid valve
7	Spindle heating	The spindle bearing preload is too large	Adjust preload
		The bearing is scratched or damaged	Replace new bearings
		The lubricating oil is dirty or contains impurities	Clean the spindle box and re-oil