Conical overlap / micro leaks

Possible cause/checklist:

  1. Slitter:
    • Angular errors below 0.05 mm per 100 mm
    • Burrs below 20% of tin plate thickness !
  2. Air pressure:
    • Welding pressure 2.6 (aerosol) to max. 2.8 bar (beverage, food), equal to 45 – 48 daN.
    • Wire tension cylinder profiling unit 1.6 bar
    • Wire chopper 2.4 bar
    • To move tooling (which air regulator find on touch screen: “Air”, page 5/8) pressure should be 3.0 bar.
    • To lift up guidance channel (page 5/8) pressure should be 1.0 bar.
  3. Lower welding arm/Z-bar:
    • Take off the upper and lower screw off one by one, check the insulation washers, if they are squeezed too much, change each them!
    • Check the insulation of the complete Z-bar:  > 10 MegaOhm
    • Measure the deflection of the X-Plane at a welding pressure of 45 daN (2.6 bar): Between 0.1 – 0.15 mm
  4. Check all the Z-bar grooves:
    • Especially the last 100 mm, incl. front Z-bar tip (called nosepiece), maybe they are worn out.
    • Sometimes some tin deposits can slow down or disturb the movement of the tin plates -> can gap unsconstant, cold begin/end.
  5. Welding roller grooves:
    • They have to be clean and the ground of each groove must be straight!
    • If you are not sure, re-groove them
  6. Copper wire width:
    • Check this according manual. Guideline: Width of copper wire always between 0.03 – 0.07 mm below profile width of welding rollers
  7. Reset the whole tooling according manual (if not yet available in your manual, ask Can Man)
    • Reset the calibration crown /tooling: Check the play of the top diabolo roller bearings.
  8. Lower welding roller height:
    • Set it around 0.3 mm over the Z-bar center. How to do:
      • Weld cans, and check the roundness:
      • Apple shape: Tooling too high, or welding roller too low or check this FAQ here
      • Roof shape: Tooling too low, or welding roller too high
      • The height of the tooling should be between – 0.2 and + 0.2 mm, shown on the handle/shaft underneath the tooling. If needed, move the height of welding roller again, till the roundness of the can is sufficient.
  9. Reset the upper pendulum rollerhead:
    • Angle: Normally not necessary, as long as nobody touched/dis-adjusted red marked screws on the support).
    • Horizontal axle: Make sure that the height of the pendulum axle is parallel to the welding roller axle. Use for this setting a precise level, and level the shaft of the pendulum rollerhead according the level of the welder, or do it according the manual, using the delivered gauge set.
  10. Position of exit conveyor:
    • Use the delivered stainless steel gauge, put it into the tooling, and let both belts (of the OHC) touch that gauge slightly.
    • Make sure the OHC is parallel to its basic plate on the lift
  11. Position of diabolo center between 1–3 mm before lower weld roll center.
    • Conical overlap:
      • Too much overlap in the beginning: Move tooling foward, 0.5 mm/move
      • Too much overlap in the end: Move the tooling backwards, 0.5 mm/move
  12. Can gap tolerance shall be within 0.5 mm:
    • Can gap on aerosol: 2.0 – 3.0 mm
    • Can gap on beverage/food: 1.5 . 2.5 mm
    • Belt for pendulum rollerhead should be tensioned tight.
    • Belt for profiling unit must be tight, before and after the profiling unit
    • The clearance between wire chopper transport rings must be 50 – 60% of the profiled copper wire thickness
      Example: Copper wire thickness 0.60 mm, clearance adjustment 0.30 mm
  13. Overlap:
    • 0.5 – 0.60, not less, not more
    • Check the overlap only by an internal diameter gauge, with a dial indicator to read result. Diameter tolerance should not be higher 0.1 mm.
  14. Check the tin flow after the upper, and after the lower welding roller on the copper wire.
    • Do not accept anything but the center
  15. Check the overtravel of the can body:
    • Move the pusher finger to the very front, and measure the distance from the pusher plate, until the center of the lower welding roller.
    • Now deduct this measure from your cutted tin plate height and you know how many mm the tin plate gets pushed over the center of the lower welding roller.
      Attention: If you have spatters on the beginning of the can, which show backwards, move the transport carriage backwards. Do that over the can height setting on the touch screen.
  16. Rollforming:
    • The rollformed body must be round, and both edges shall be parallel to each other
    • Rollforming overlap: E.g. ø 65, min. 5 mm, max. 8 mm
  17. Check following after all these settings:
    • Weld 10 cans and do not cut the copper wire:
      • Check the wire gaps (gap between tin flows) on the copper wire. Tolerance should be < 0.5 mm
      • Measure each wire elongation, and compare them. Tolerance should be < 0.5 mm

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