High-quality can lids play a critical role in metal can production. Below are the most common stamping issues and recommended solutions.

1. Uneven Width of Bottom Lid Outer Flange
Cause: Uneven pressure from the upper die ring during the downward punch, resulting in varying flange widths.
Solutions:
(1) Verify that the punch installation is correct and that there is no uneven tightness on one side.
(2) Ensure mold fit tolerances meet the required standards to improve precision.

2. Bottom Cap Breakage
Cause 1: Misalignment of the pusher head.
Solution: Adjust the pusher head positioning.
Cause 2: Poor tightness of the pressure plate.
Solution: Adjust the pressure plate tightness.
Cause 3: Insufficient tightness of the discharge pressure strip.
Solution: Tighten the discharge pressure strip.
Cause 4: Worn or loose parts in the transmission mechanism (such as the transmission shaft, bevel gear, or eccentric wheel).
Solution: Replace worn components or tighten the mechanism.

3. Bottom Cap Scratches
Cause 1: Rough pusher head surface.
Solution: Polish the pusher head with metallographic sandpaper.
Cause 2: Burrs on the baffle.
Solution: Polish the baffle or cover it with adhesive tape.
Cause 3: Tight fit between upper and lower dies or inadequate chamfer/surface smoothness.
Solution: Round the edges of the die cores, ensure proper tolerances as per design drawings, and increase oil application on the sheet metal if necessary.

4. Cap Surface Impressions
Cause 1: Poor quality of incoming material printing.
Solution: Sort out or reject low-quality incoming materials.
Cause 2: Debris in the mold cavity.
Solution: Use a cloth or air gun to clear away any debris.

5. Wrinkled Outer Flange
Cause 1: Excessive gap between the upper die ring and the lower die core’s outer flange.
Solution: Adjust the gap as needed.
Cause 2: Uneven pressure during rolling, causing uneven shrinkage of the sheet.
Solution: Increase the spring or rubber gasket pressure on the lower die and adjust gasket positioning for even pressure distribution.

6. Failure to Pick Up Sheets
Cause 1: Damaged or deformed suction head causing air leakage.
Solution: Repair or replace the suction head.
Cause 2: Uneven suction head height.
Solution: Adjust all suction heads to a uniform plane.
Cause 3: Low placement of the travel limit switch.
Solution: Raise the travel limit switch position.
Cause 4: Faulty vacuum pump.
Solution: Repair or replace the vacuum pump.

7. Poor Cap Ejection
Cause 1: Blocked exhaust holes in the upper and lower die cores.
Solution: Enlarge or clear the exhaust holes.
Cause 2: Insufficient spring tension in the lower die discharge ring or limited flexibility in the upper die discharge ring.
Solution: Increase spring tension by adding a thicker rubber gasket and inspect the upper die ring as well as the inner chamfer of the upper blade.

8. Burrs
Cause: Dull cutting edge or excessive gap between upper and lower blades.
Solution: Perform heat treatment on the cutting edges to enhance hardness, then grind to ensure sharpness and maintain proper fit.

9. Triangular Cap Edge
Cause: Poor groove design in the circular capping machine, oversized inner diameter of the upper blade, or excessive edge length after forming.
Solution: Ensure a correct fit between the upper blade and the lower die core, form a right angle at the cap edge, and maintain accurate groove design in the circular capping machine.