Troubleshooting printing machinery takes patience and time. Everyone wants the problem solved immediately. Rather than trying to rush to a solution, it is best to take the time and find the root cause of the problem. Time and patience will solve it.
When a problem is noticed, the operator should look at every stage of the process. First, find at which stage the problem started then find the cause. Here are some hints to help you solve a few common problems. Always remember to keep a log book with the problems and solutions. They'll be easier to solve next time around.
Don't forget to write your original settings down before you begin troubleshooting. Try one thing at a time. If it doesn't work, return to the original settings and try something else.
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| Unexact cutting edges |
Wrong knife angle |
Knife with cutting angle of 22° and a prefase of 28° |
| Cutters are worn out |
Use of sufficiently sharp and exact cutters |
| Film stacks are too high |
Reduce the stacks height: take 10 cm as an approximate height |
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Poor sheet guiding
(blocking, double-sheet feeding, etc.) |
| Stock and handling conditions have not been kept |
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| Store film in original packaging; if possible remove packaging 24 hours before handling and store film in printing hall; a relative humidity of at least 55% is recommended |
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| Format stacks are too strongly charged |
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| Do not stack more than two pallets on top of each other |
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| Fan and/or lift up outer sheets before printing |
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| Film sheets stick together/stick to machine due to electrostatic charge |
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| Separate film sheets with ionized air |
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| Printing speed is too high |
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| Reduce printing speed (depends on machine) |
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| Insufficient ink key |
Inappropriate ink |
Use printing ink which is suitable for polymer type and drying procedure |
| Surface tension is too low |
Use pretreated film (Corona, DYNOX®) |
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Printing ink is not scratch resistant
Film sheets stick together after printing
Printing ink is passed on to next sheet
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Unsuitable printing ink |
Use printing ink which is suitable for polymer type and drying procedure |
| Printing ink has not been sufficiently hardened/dried |
Evaporate drying: increase amount of air, if necessary, air temperature |
| UV-drying: optimize/clean UV-heater |
| Oxidative drying: use a film with sufficient roughness depth/check composition of fountain solution (ph-value) |
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| Film breaks |
Punching tool is damaged |
Change punching tool or punching support |
| Film is too cold |
Do not process film under a temperature of 15°C |
| Film is not sufficiently impact resistant |
Use a film with higher tensile strength |
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| Bond strength of gluing line not strong enough |
Unsuitable glue |
Use only glue which is recommended for the polymer being used |
| Speed of machine is too high |
Adjust speed |
| Contact pressure or contact time is too low |
Raise pressure/speed |
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| Glue line discolors (APET, GAG) |
Solvent glue has been used |
Use PU-Hotmelt (APET, GAG); if necessary, a glue with slower effect (GAG) |
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| Vapor locks generate in the glue line (PU-hotmelt) |
Contact pressure is too low |
Use suitable glue |
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