A Game of Tones - Winter is coming

If we look back at the history of can making, roller temperatures increased steadily as print speeds increased. Of course print speed is not the only cause of high temperatures, but it substantially contributes to the overall temperature of the ink at application. Machine manufactures have heard the calls for help and have provided various solutions to lower roller temperatures. Temperatures have been lowered to such a degree where application temperatures can now be too low. Most inks will work over a wide range of temperatures, but in order to achieve the best appearance and mileage results, we consider +/- 40oC/104oF as being the ideal. The best way to achieve temperature consistency through seasonal variation would be through thermal regulation as opposed to chillers. 

Can Plant locations are often positioned in regions were temperatures vary from -20 oC/-4 oF to +40 oC/104 oF. This variation in ambient temperature will affect roller temperatures, but more importantly it will have a dramatic effect on substrate temperature. Modern Can Plants often benefit from being kitted out with the most sophisticated and energy friendly machines. Ovens are more insulated for thermal efficiency, meaning that once the external ambient drops, the internal temperature follows, due to the lack of dedicated heating. Can Plants being cold is not something we used to talk about as it never used to happen but now is becoming typical. As the internal temperature drops, so does the substrate temperature. Colder substrate temperatures means that the ink is more likely to reticulate. Adding common ink reducing solvent is often used to improve this reticulation. However these solvents often have a relatively high freezing point and tend to offer less benefit on cold substrate. Another option to improve ink reticulation is increasing the print pressure. This can work very well in certain situations, but not on cold substrate as the reticulation occurs after printing, not during printing.

Cold substrate is not just aside effect of newer Plants. Even established Plants can have their issues. Compressed air is often used in the manufacturing process. The temperature of the air can be critical to substrate temperature. Compressed air is often used to help with the deco infeed. If the air is too cold and given the speed of the print process, the can may stay cold during the print process.

Many process problems often result in a similar print defect, but the route cause and therefor the solution maybe very different. The clues to deciphering the problem are usually on the can, it just takes someone to read them.