Common troubleshooting and maintenance guide for drilling and tapping machines

1. Common fault diagnosis and troubleshooting for drilling and tapping machines

• Drill/tap related faults

Drill bit breakage or wear is one of the most common faults, which is mainly manifested by reduced processing effect and increased hole wall roughness. When the drill bit is found to be broken or severely worn, it must be stopped and replaced immediately.

The causes of this problem include:

The drill material does not match the workpiece

The feed speed is too fast or the speed setting is improper

Insufficient cooling and lubrication leads to overheating

The drill bit has been used for too long and has become passivated

The main manifestations of tap problems are "blunt thread" (insufficient thread depth), "slipped thread" (thread is messy) and tap breakage. Blunt thread is usually caused by too large bottom hole diameter or too small return rod diameter, and the correct bottom hole diameter needs to be recalculated or selected. Slipped thread is mostly caused by using too blunt taps, improper pressure or lack of lubricating coolant. The solution is to replace sharp taps and ensure the use of appropriate cooling lubricant. Tap breakage may be caused by over-aggressive operation, chip blockage and failure to reverse in time, or over-hardening of the tap. Pay attention to the operation method and remove chips in time.

• Abnormal machining accuracy

When the drilling position is inaccurate, the possible reasons include:

Positioning device offset or damage

Loose fixture or inaccurate positioning reference

Lower motion accuracy due to wear of machine tool guide rails

Abnormal CNC system parameters

Solutions include recalibrating the positioning device, tightening the fixture, checking the guide rail clearance, and reviewing the CNC program and parameters. For tapping position deviation, it is also necessary to check the coaxiality of the tapping axis and the drilling axis. Abnormal output parameters are manifested as changes in machining accuracy, decreased efficiency, or a sudden decrease in feed volume, which may be caused by leakage, blockage, or machine tool operation with disease. The hydraulic and pneumatic system, transmission mechanism, and control system need to be fully checked.

• Abnormal mechanical operation

Excessive vibration and noise are another common fault, and the failure rate of automatic drilling and tapping machines is as high as 60%-80%.

Possible causes include:

Defects in machine tool design or manufacturing

Wear of parts or unbalanced movements

Dry friction caused by poor lubrication

Damage to transmission parts (such as bearings, gears)

Unstable equipment foundation or loose fixing bolts

When abnormal knocking sounds occur, it may be caused by loose parts or unbalanced rotors. The machine should be stopped immediately to check the tightness and balance of each moving part. Overheating of the machine is also a dangerous signal, which may be caused by cooling system failure, poor lubrication or overload operation. It is necessary to check the coolant circulation system and the oil supply of the lubrication points, and arrange the processing tasks reasonably to avoid long-term continuous high-load operation of the equipment.

• Electrical control system failure

The failure of the tapping machine to reverse is a typical electrical control system failure. Possible causes include:

Motor failure (winding open circuit, bearing wear, drive damage)

Transmission system problems (belt break, gear wear, coupling looseness)

Abnormal control signal (controller failure, wiring error, sensor failure)

Program failure or sensor damage can also cause equipment abnormality. The sensor of the tapping machine is equivalent to the "brain". If it is damaged, the equipment will not be able to process materials normally. It is necessary to check whether the signals of each sensor are normal and replace the damaged sensor if necessary. The machine may fail to start due to power supply problems (poor contact, insufficient voltage, blown fuse) or damage to the internal components of the machine. The power supply system should be checked first, and then the internal circuits and key components should be checked.

2. Daily maintenance points for drilling and tapping machines

• Regular inspection and maintenance plan

Establishing a complete regular inspection system is the key to preventing failures.

Before starting the machine every day, check:

Is the lubricating oil level normal

Is each moving part flexible and free of jamming

Is the fastener loose

Is the air source pressure stable

Weekly maintenance includes:

Cleaning the guide rails, ball screws and relubricating

Checking the belt tension

Cleaning the coolant tank and filter

Checking whether the electrical terminals are tight

Perform comprehensive maintenance every month:

Replace the lubricating oil

Check the spindle radial runout

Calibrate the machine tool accuracy

Test the effectiveness of safety protection devices

• Special maintenance of key components

The spindle system is the core of the machine tool, and special attention should be paid to:

Regularly replace the spindle lubricating oil

Monitor the spindle temperature rise

Avoid the spindle from being subjected to excessive radial force

Use special tools to disassemble and install the spindle bearings

Maintenance points of guide rails and screws:

Clean the guide rail surface daily

Use the specified brand of grease

Regularly check the guide rail clearance

Avoid chips accumulating on the screw

Maintenance of the tool system:

Check the wear of the drill bit immediately after use

Store the drill bit correctly to avoid collisions

Regularly sharpen the drill bit to keep it sharp

Use special tool holders to improve clamping accuracy

3. Operating specifications and usage tips

Correct operating habits can significantly extend the life of the equipment:

Reduce pressure when drilling a hole to avoid twisting the drill bit

Drill the center point before drilling to guide the drill bit to position correctly

Use appropriate cutting fluid and pay attention to chip removal

When processing cross holes, drill large diameter holes first and then small holes

Avoid using too blunt taps for processing

Apply appropriate pressure when tapping, and do not apply too much pressure after reaming a few teeth

For high-speed drilling and tapping machines, special attention should be paid to:

Choose taps with appropriate quenching

Remove chips in time to prevent blockage

Use emulsions, engine oil, etc. as cooling lubricants