Support

3 Support Entries
  • Take off the copper wire completely.
  • If powder tubes are in use, take them off too.
  • Take off the nosepiece, and clean its positioning slot very carefully!
    Special attention is needed in the area of the front pin.
  • Measure the resistance between lower welding arm and the Z-bar support/long Z-bar.
    • The restistance must be endless.
  • If the measured value is too low, take off one after the other screw underneath the lower welding arm.
    Attention: Do not take off all screws, the lower welding arm will fall down!
  • Check if every screw has an insulation ring and tube.
  • Blow off all holes by air pressure.
  • Check if the long insulation stripes on each side of the Z-bar are in.
  • If the restistance is still not good, the secondary unit may have somewhere else a contact with the ground.
  • Check the hole secondary circuit.
    • The secondary circuit must not be connected to the ground!

Report all steps, new or different settings, old and new production parameters (can size, cpm, weld speed, weld current, weld frequency, current wave-form and transformer step) for an easier overview and follow-up!

Open a new ticket and add your document!
Note on which tin-plate parameters (thickness, hardness, tin coating inside / outside, rolling direction, BA or CA, supplier, printed or not) such faults occur, and on which tinplates not!

Basic parameters & settings to be checked first

  1. Tin-plates must be cutted within the allowed tolerances:
    • Measure the tin-plates and report if out of tolerance!
    • Follow sheet „blank-cutting tolerances“!(www.canman.ch/SUPPORT/Canmaking/002)
    • Are all tin-plate parameter clear and noted: Thickness, hardness, tin coating in and outside, rolling direction, BA or CA, supplier, printed or not
  2. Can-bodies must be correct rollformed:
    • Not conical and best roundness must be reached!
    • Overlap of both tin-plates edges:
      • ø52 ~ 5mm
      • ø99 ~ 15mm
      • ø153 ~ 30mm
      • ø284 ~ 60mm
  3. The copper wire must be correct profiled and the surface not damaged:
    • The width of the profiled copper wire shall always be 0.05 mm smaller than the profile-groove in the weld rollers!
    • Measure the width of the profiled copper wire within around half a meter on several position, and note the variations. Maximum difference of 0.05 mm are allowed. If you measure more, check the concentricity of the profiling rings.
    • Change the copper wire profiling rings or idler/guide wheels if the surface of the copper wire shows a damage!
  4. Both weld rolls must be regrooved after its regular groove life-span:
    • To avoid unexpected heavy weld faults it is recommended to implement the total piece-counter and the regrooving interval into the production order!
    • As an example:
      • Upper weld disc ø 90 mm to be regrooved after 3 mio cans (interval depends on, type of welder, type of weld roll and welding speed).
      • Lower weld roll ø 62 mm to be regrooved after 2 mio cans.
      • Total piece counter at production start at 28 mio welded can bodies, upper weld disc has been regrooved at 25 mio, therefore to be regrooved now! Lower weld roll regrooved at 27.5 mio, therefore to be regrooved at 29.5 mio.
    • After every regrooving weld roll and / or z-bar must be repositioned: Use the correct to reset the lower weld roll and/or nose-piece, and the upper welding roller!
  5. The z-bar must be clean in and outside – and not worn -, calibration crown must be clean, and are all pre-calibration rollers shall turning easily:
    • A dirty z-bar may not be well insulated, therefore the risk of wear is higher and the weld current is flowing over z-bar and tin-plate to the weld center!
    • Note: The insulation of the secondary circuit should be controlled yearly!
    • Non turning pre-calibration rollers can create body-offset and unconstant can gap!
  6. The calibration crown center must be correct positioned to the weld center:
    • The center of the crown must stay between 3 – 1 mm before the center of the lower weld roll (in weld direction seen).
  7. The position and speed of the exit conveyor (all conveyors which transport the can body out of the weld center) must be aligned perfectly.
    • Both belts have to touch the can body similar. The direction of the conveyor must be absolutely parallel to weld direction!
    • The gap between two can bodies on the exit conveyor should not be higher than10 – 20 mm! (if can gap is 1.5 – 3.0; see „can gap“ in point 12.)
    • A driven diabolo roller must run the same speed like the copper wire!
  8. Both tin-layers must be centered and parallel on the copper wire:
    • That means that all mechanical settings are correct!
  9. The copper wire tension and elongation must be correct:
    • Make sure that the air-pressures for the pneumatical cylinders are set correct, or the copper wire is in the right groove of the wire drive disc (Soudronic m/c’s only).
    • Measure the copper wire elongation after the lower weld roll, or after the weld roll before the wire chopper: Elongation varies between 0 – 4% of the can body height.
    • A sufficient copper wire tension is important to avoid a sliping copper wire on the weld rolls!
  10. The can body overtravel must fit:
    • Set the overtravel according manual / scale on the transport carriage!
    • Measure how many mm the can body will be pushed over the center of the weld rolls.
  11. The welding pressure must be set correct:
    • Welding pressure for Wima welders vary between 35 and 50 kg / daN. Start with ~ 45 kg / daN. Check the manual to convert in bars.
    • 50 Hz welder using welding pressures between 35 – 45 kg/daN, while automatic welders running between 40 – 50 kg / daN.
  12. The welded overlap must be correct, and on begin and end within allowed tolerance:
    • Correct welded overlap depending on z-bar:
      • Z-bar of 0.4 mm results in a welded overlap of 0.5 – 0.6 mm
      • Z-bar of 0.6 mm results in a welded overlap of 0.7 – 0.8 mm
      • Z-bar of 0.8 mm results in a welded overlap of 0.9 – 1.0 mm
    • If the overlap is not correct, adjust until overlap is correct:
      • Reset the calibration crown if needed with the mandrel. The diabolo-rollers should not have any radial-play!
      • Adjust the overlap according manual.
    • Once the overlap has been set, double check and set the can gap. Increasing the overlap will reduce the can gap, decreasing the overlap will increase the can gap.
    • Weld around 5 cans and measure the gap between the tin-layers. A good can gap measures between 1.5 – 3.0 mm. Any variation should be within 0.5 – 1.0 mm.
  13. The weld current frequency must fit:
    • Welders with a static frequeny inverter should have a welding spot length between 0.6 – 1.2 mm.
    • A welder without static frequency inverter should be operated between 8 – 12 m/min. Reducing the welding speed does decrease the welding spot length.
    • The welding spot lenght should always be as long as possible (by reducing the frequency) to reduce energy and heat in the welding seam and in the welder to a minimum.
    • Main target must be a flexible and smooth welding seam!
  14. The main weld current must be set correct!
    • How to do:
      • Reduce weld current until cold weld zones appear. Tear-off test must be done at an angle of 30 – 45°, means try to pull-off the top tin plate edge. To be done from each side. Note the weld current value!
      • Increase weld current until hot weld appears. Tear-off test must be done at an angle of 0°, means pull-off the seam only and find out when the seam starts to become fragile. Note the weld current value!
      • Add 2/3 of the weld current difference between cold and hot weld seam to the cold weld seam value, and start the production!
    • Set beginning and end time and beginning and end current!
    • Note: If the welder is running with triangle wave-form, make sure the duty-cycle is between 80 – 90%. If the welder is running with sine wave-form, make sure the right transformer step has been choosen! Contact us if you are not sure.
  15. The seam-extrusion inside and outside must be equal!
    • If the seam extrusion is bigger inside, reduce the height of the calibration crown. If the seam extrusion is bigger outside, increase the height of the calibration crown.
    • The shape or roundness of the can-body is not so important as a correct seam-extrusion!
    • The seam extrusion inside depend on the inner weld roll diameter as well: The diameter difference of upper and lower weld roll should be as small as possible.

 

Checklist to avoid micro leaks

Micro leaks can occur within the seam and beside the seam – especially on cold-formed areas like necking, beading, flanging or seaming -, even if all above mentioned basic parameters & settings seems to be correct.
Micro leaks can have various sources: Wrong settings on the welder, tin-plate parameters which support such faults, worn or wrong machineries in the downline, or tin-plate parameters which do not fit to beader, necker, flanger and seamer.

For a better visual understanding put the faulty-can bodies in a water bath, and inspect the leaking area by a microscope. Store the pictures if possible!

  1. Make sure that necker, flanger, beader and seamer are in good conditon, and do not stress the weld seam more than needed.
    • For further information check the manuals (check the tin-plate specifications range) or contact the supplier!
  2. Try to weld different tin-plates to understand which tin-plate parameter can be produced without such faults.
    • Rolling-direction parallel to weld seam can increase the occurence of micro-leaks!
  3. Micro-leaks in and near the seam can be reduced by changing the energy in each welding spot:
    • Reduce the welding frequency within the possible range (see point 13. in above checklist), and set the main weld current again (see point 14. in above checklist). The production cycle (cpm) must probably be reduced to reach a good weld seam. Produce a certain number of cans and test them.
    • Increase the welding frequency within the possible range, and set the current again. Produce a certain number of cans and test them.
    • Reduce the welding pressure to max 45 kg / daN, and set the main weld current again (see point 14. in above checklist). Produce a certain number of cans and test them.
    • Reduce the welded overlap by around 0.10 mm, and set the main weld current (see point 14. in above checklist). Produce a certain number of cans and test them.
  4. If above listed does not help, some theoretically wrong settings could help:
    • Increase the can gap to have completely different welded begin and end. Produce a certain number of cans and test them, and set back if it didn’t helped!
    • Set a slight can-body offset, to bring the current different into the tin-plate. Produce a certain number of cans and test them, and set back if it didn’t helped!

 

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  • Empty the water tank. On 2-circuit cooling unit only cold water tank has to be emptied.
  • Blow off one by one each cooling circuit in the welder. This allows to empty each circuit separately. If your welder has a 2-circuit cooling system only the circuit for the lower and upper weld roll has to be emptied.
  • Change the filter cartridge and clean the filter housing inside.
  • Fill the tank with water only, open main valve Y14, and run the system for at least one hour to flush rests of old emulsion out.
  • Empty the water tank again and clean again if necessary.
  • Fill the water tank with water (or distilled water if requested), and mix the PowerRoll™ coolant H1 in with 8 percent.

We recommend following maintenance procedures:

  • Change the filter cartridge monthly.
  • Change the cooling emulsion yearly. Use the PowerRoll™ cooling system cleaner at any time you change the emulsion.
  • Use the PowerRoll™ cooling system decalcer after around 5 years.

Order numbers:

  • PowerRoll™ coolant H1 (food grade), 7 Liter, 011494
  • PowerRoll™ cooling system cleaner H1 (food grade), 10 Liter, 011495
  • PowerRoll™ cooling system decalcer, 25 kg, 011496
  • Filter cartridge 50 µm, 002446

Safety data sheets see below: