How to restore the mechanical accuracy of a machine tool after a collision

After a collision, to restore the mechanical accuracy of a CNC milling machine, it is necessary to first check the degree of damage, and then gradually calibrate and reset it step by step from easy to difficult to avoid forced startup causing secondary damage.

Ⅰ, shut down the machine for inspection to determine the degree of damage

Minor collision ‌ : Only the tool is damaged and the fixture shifts, with no obvious structural deformation. Simply replace the damaged tool, recalibrate the fixture's clamping position, and tighten all loose parts.

Moderate collision ‌ : Scratches on the guide rails, increased spindle clearance, and transmission jamming occur. Partial disassembly and maintenance are required to repair the damaged contact surfaces.

Severe collision ‌ : column offset, spindle bending, bed deformation. The damaged structure must be disassembled to correct the reference, and the deformed parts should be replaced if necessary.

Ⅱ. Precision reset operation of Core Components

1. guide rail system repair ‌

Use a standard straightedge and dial indicator to check the straightness and flatness of the guide rail, and mark the positions of wear and scratches.

For minor scratches and wear, finely grind with an oilstone or manually scrape and level. Adjust the gap between the guide rail inserts to ensure smooth movement of the worktable without shaking.

2. Calibration of ‌ lead screw drive system ‌

Disassemble and inspect the mating surface of the lead screw and nut, clean up iron filings and impurities, and repair slightly worn parts.

Adjust the preload force of the transmission, eliminate the idle stroke clearance of the feed, and avoid sudden changes in size during processing.

3. Precision debugging of the ‌ spindle system ‌

Use a dial indicator to check the radial runout and axial movement of the main shaft cone hole diameter. If the values exceed the standard, replace the aged bearing.

Adjust the tightness of the main shaft to ensure there is no obvious swing or abnormal noise during high-speed operation.

Ⅲ. Calibration of the overall geometric accuracy of the machine

Use a precision level to adjust the level of the machine tool bed and ensure that the benchmarks of each axis are aligned.

The repeat positioning accuracy of each axis is detected by a laser interferometer, and the error is corrected through the backlash compensation function of the numerical control system.

Check the core geometric parameters such as the flatness of the worktable, the perpendicularity of each axis movement, and the parallelism of the spindle axis one by one.

Iv. Final Verification Stage

Run the equipment at low speed without load to break it in and confirm that it operates smoothly without any abnormalities.

Select standard workpieces for trial milling processing. After verifying that all processing indicators such as flatness and perpendicularity are qualified, they can be put into formal production.