Transferring high viscous printing inks is a continuous challenge for a large publishing house
The ink industry represents one of the most versatile application sectors for delivery systems: The reliable supply of sometimes abrasive, corrosive or extremely high viscous printing inks and varnishes as well as their precise metering cannot be covered by standard pumps, as they don’t fulfill the wide range of requirements, especially since the usually very sensitive media require careful transport. Instead, this industry often relies on progressing cavity pumps and rotary lobe pumps marked by their wide adaptability and pressure-stable delivery characteristics.
The underlying delivery principle of volumetric displacement works nearly without pulsation and can be regulated precisely via the rotational speed.In addition, engineering design permits numerous configuration versions regarding materials and geometries. Thus, the right pump can be put together for any use to ensure long service life and high efficiency in spite of the challenging conditions.
One of the major challenges in delivering inks is their lack of fluidity. Viscosities of 10,000 mPas and more are quite common. Continuous supply can therefore be achieved only with some difficulty; in addition, the pumps become clogged quickly.
For example, a renowned publishing house struggled with delivery breakdowns at the diaphragm pumps used to refill offset ink from the transport truck to the storage tanks, which delayed the unloading process greatly. What’s more, the pumps often required maintenance work and had to be removed and dismantled quite laboriously.
To increase performance, reliability and economy at this point, and to minimize maintenance efforts the company finally resorted to NEMO® progressing cavity pumps from NETZSCH.
A NEMO® progressing cavity pump with single-stage L-geometry for rotor and stator was selected for this application, which allows for a high delivery rate at low differential pressure. The deliberately chosen undersize of the rotor prevents excessive clamping, meanwhile improving mechanical efficiency of the pump. Thereby, the unloading time for the ink was reduced by nearly half and the reliability of the process was increased. Furthermore, the slim design of the progressing cavity pump allowed the installation of four pumps – for the four printing inks – together with frequency inverters on a carrier module integrated in the base plate of a transport truck. It can be easily removed with a forklift truck to allow free access to the devices, in case maintenance work should once become necessary. Nonetheless, the pumps generally work much more reliably than the previously employed diaphragm pumps.