Background

A leading Indian converter, manufacturing flexible packaging laminates, has an 8 colour rotogravure printing press. Print runs include both surface and reverse printing on films and paper. Web width is 1300 mm and rated speed of the press is 280 meters per minute. Solvent based inks with a viscosity of 16-20 seconds (B4 cup) are normally used. The client wanted to optimise solvent consumption, without compromising the print quality.

Process

On each print station, an ink circulating pump delivers ink from the tank to the tray (pan) through a filter. As the print run progresses, temperature of the ink rises and then stabilises at a high temperature over time. The high ink temperature results in high solvent evaporation, which in turn results in higher top-up solvent consumption.

Solution

A heat exchanger was needed to reduce ink temperature to a level that reduces solvent consumed, without hindering the process. Critical design parameters included temperature and low rate of the ink, permissible pressure drop of the application and quantity of heat to be transferred through the heat exchanger. We evaluated the application data through heat exchange and CFD modelling to arrive at a compact design with optimal performance.

The Valflow ink temperature controller (ITS) uses water as the medium of heat transfer. It has a dependable (leak proof) construction and has a low pressure drop. It is sleek, easy to clean and simple to retrofit.

Result

Without a heat exchanger, temperature of the ink stabilised at 33°C when productivity was at an optimum level. With the help of the Valflow ITS, ink temperature during operation was reduced to 26°C. Lowering ink temperature by 7°C saw a reduction in top-up solvent consumption by 35%, while maintaining the same printing performance.

Conclusion

Annualised savings after installation of a Valflow ITS, with associated accessories, water chilling plant, etc. is significant, translating into a payback period of about 9 months!

AxisValence has extensive experience and expertise in various applications across industries, which we leverage to provide a suitable solution for your application.