Ink-Cooling: Sustainable Savings in Ink Consumption
A constant ink temperature contributes significantly to stable conditions during the printing process. Besides a possible influence on solvent evaporation, practical experience shows that ink consumption in particular offers significant potential for economic savings.
Solvent Consumption and Ink Cooling
Cooling the printing ink can reduce solvent evaporation. At the same time, the regular cleaning of the cooling station requires additional solvent. When considering the overall process, the economic impact on solvent consumption is therefore usually small, especially since printing ink represents a significantly higher share of the total material costs.
Why a Constant Ink Temperature Is Important
During the printing process, the ink heats up due to ambient temperature, heat generated by the printing machine and mechanical stress.
As the temperature increases, the viscosity of the ink changes and the ink becomes more fluid. Both flow cups and automatic viscosity measurement systems therefore register a lower viscosity.
A constant ink temperature creates stable and reproducible process conditions. This allows the viscosity to be controlled more precisely and the ink consumption to be optimized.
As a general rule:
An increase in temperature of 1 °C reduces the flow cup time by approximately 0.1 seconds.
An example:
At 20 °C, a printing ink containing 65% solvent and 35% ink has a flow cup time of 20 seconds.
If the same printing ink heats up to 25 °C, the measured flow cup time decreases to approximately 19.5 seconds due to the temperature change alone (thixotropic behavior).
How Temperature Leads to Higher Ink Consumption
The automatic viscosity control system detects the apparently lower viscosity and stops adding solvent. However, during this time, solvent continues to evaporate from the printing ink.
Only when the measured value reaches the target value of 20 seconds again does the system start adding solvent.
By this time, however, the mixing ratio has already changed.
For example, from: 65% solvent / 35% ink to: 60% solvent / 40% ink
The proportion of ink has therefore increased significantly.
The Economic Consequences
A higher proportion of ink automatically results in:
- higher ink application to the substrate
- increased ink consumption
- higher material costs
- possible colour shade variations
- fluctuating print quality
The more the printing ink heats up during production, the greater these effects become.
Constant Temperature – Constant Costs
Ink cooling prevents these temperature-related fluctuations. The ink temperature remains constant, which also helps to keep the ratio between ink and solvent stable.
The result is a consistent ink application, reproducible print quality and significantly lower ink consumption.
Even if some additional solvent is required for cleaning the cooling station, this small additional consumption is generally compensated many times over by the savings in ink consumption.
Advantages of a Plate Heat Exchanger Compared to Pipe Cooling
For our ink cooling solutions, we exclusively use plate heat exchangers. They are integrated directly into the bypass of the viscosity control system, providing efficient and controlled cooling of the printing ink.
Compared to conventional pipe cooling, plate heat exchangers offer several important advantages:
- High cooling capacity: Due to the large heat transfer surface and efficient heat exchange, the ink temperature can be reduced quickly and maintained at a constant level.
- Compact design: Plate heat exchangers require very little installation space and can therefore also be easily integrated into viscosity systems on existing printing machines.
- Attractive investment costs: Compared to the cooling capacity provided, the initial investment is relatively low.
- No separate manual cleaning: The plate heat exchanger is part of the bypass circuit and is automatically flushed and cleaned together with the viscosity control system.
- Efficient cooling of small flow volumes: Since only the defined bypass flow is cooled, heat can be efficiently and specifically removed from the printing ink.
- Easy retrofit: The compact design allows integration into existing installations without major modifications to the ink circulation system.
In comparison, a conventional pipe cooling system generally requires significantly more installation space and pipe length to achieve a comparable heat transfer surface and cooling capacity. The plate heat exchanger therefore provides a compact, powerful and economical solution for maintaining a constant printing ink temperature.
Conclusion
The main economic benefit of ink cooling is not the reduction of solvent consumption, but the stabilization of the ink temperature.
It prevents temperature-related viscosity measurement deviations, keeps the ink-to-solvent ratio stable and sustainably reduces ink consumption.
Since printing ink represents by far the largest share of material costs in the printing process, this is where the greatest savings potential can be achieved – while at the same time improving process stability and maintaining consistent print quality.
Related Files
- Product sheet «OP-TC-EN» (1 MB)