How to test used cnc punching machine

Author:J           Date:2025-09-13

Phase One: Static Inspection (Power Off)

This forms the foundation of all testing, aimed at identifying visible wear and damage. First, examine the appearance and structure. Inspect the bed, frame, and worktable for cracks, repairs, or rust. Severe rust indicates the used cnc punching machine was previously exposed to harsh environments. Open protective covers to inspect the transmission system. Check gears and drive shafts for chipping or wear; Check belts for aging and slack. The critical focus is evaluating the guideways and lead screws. Touch the X and Y-axis guideways to feel for noticeable wear pits; attempt to wobble the lead screws to detect axial and radial play. Excessive play will directly cause loss of positioning accuracy. Finally, inspect the hydraulic and pneumatic systems. Check for oil leakage traces on cylinders and pipe fittings, and verify if the pressure gauge maintains pressure.

Phase Two: Dynamic Testing (Powered On)

After confirming no obvious static defects, proceed with powered testing. First, perform an unloaded operation test. Without mounting any mold, run the machine at maximum speed through complex trajectory programs (e.g., circles, squares). Listen for abnormal vibrations or harsh noises during high-speed starts, stops, and direction changes of the spindle drive and X/Y-axis servo motors, as these indicate the condition of the transmission system. Next, test core functions: verify the indexing accuracy and repeatability of the C-axis (mold rotation axis); ensure the clamping and releasing of the vise are forceful and synchronized; and confirm the lubrication system delivers oil to all guideways and lead screws at regular intervals and in precise quantities.

Phase Three: Precision and Function Verification

This is the critical stage to determine if the machine tool is fit for purpose. Conduct positioning accuracy and repeatability tests. Using a laser interferometer is the professional approach. If resources are limited, place a dial indicator on the worktable surface. Program the machine to repeatedly move to the same point and observe the dial indicator's reading deviation. Repeatability should be within ±0.03mm. Perform mold and turret tests. Install a die set and perform continuous punching to observe whether the process is smooth and free of abnormal noises. Test the turret's indexing and die-changing actions to ensure smooth rotation, accurate positioning, and no misalignment or collisions. Conduct sample punching tests. Punch a sample plate containing various hole patterns, step-punch contours, and louvered sections using a small steel plate. Carefully measure the finished hole dimensions, contour straightness, and burr height. Uniform, minimal burrs are normal; however, excessive or uneven burrs indicate incorrect punch-to-die clearance or worn/dulled tools.

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