Cooling in Printing
Throughout the printing process heat is generated as a result of friction between component parts and then transferred to ink and paper. There is also an elevated ambient temperature within the press room. This increased heat can deteriorate the quality of the ink and the overall quality of the printing operation. Cooling in printing can preserve and improve print jobs and extend the life of printing equipment.
Moisture is Important
Many outside the printing industry take for granted the fine details and attention required to create the printed materials we read and enjoy every day. For example, did you know that there is moisture in paper?
Yes, paper is hygroscopic. This means that paper either absorbs or releases moisture to maintain balance with the moisture in the air. Moisture content is important for inkjet, laser, digital and offset printing, and if unbalanced, it can affect toner adhesion, paper jams, fuser roller temperature, interaction between ink and paper, and ultimately the overall quality of the print job.
Effects of Heat
Because moisture is an important factor in printing, operations are acutely aware of heat. Heat, a natural byproduct of printing created by friction and speed in the printing process, causes moisture in paper or the surrounding air to evaporate, lowering the moisture content. Heat also affects the viscosity of the ink. Ink viscosity increases at lower temperatures, which will slow ink flow and print density. It can also cause mottled print and excessive linting. When temperatures rise, ink lowers in viscosity and over emulsification can occur. Heat can also lead to ink dripping, smearing, misting, or spitting.
Printing Industry Cooling Options
Some printing operations use fans and air conditioning systems to address heat issues within their facility. Some large scale printers and are equipped with internal fans to help regulate and cool the printing process. Due to the unstable chemicals and compounds used, fans are often required to remove and exhaust harmful fumes and odors. Some fans are engineered to work within exhaust systems.
Another option for removing heat is a vent system. This works much like a dryer vent in the laundry room. Heat created in the printing process is forced outside through a vent. Ventilation kits are available for some printers and duplicators. These are exhaust ventilation systems that remove air directly from the machine to an exterior location.
Chillers apply the most direct form of cooling in the printing process. In the printing industry, industrial chillers remove heat generated by the friction of printing rollers and cool down the paper after it comes out of the ink drying ovens.
As printing machines improve and increase in speed, temperatures of all printing processes become higher. Roller temperature during the press’ start-up phase and in full operation is an important factor to control to protect ink quality. Chillers are specially designed to regulate temperatures, decreasing print time and improving efficiency.
A chiller cools process fluids, typically water or a water/glycol mix. These process fluids remove heat from rollers and other component parts, paper, and ink. The fluid absorbs the heat from the printing process and is then recirculated through the chiller to cool again and again. Using a chiller in the printing process is a cost effective and reliable method or reducing high temperatures, saving time, and preserving machinery and materials.