Inkjet printing system and method for controlling jetting temperature

An inkjet printing system comprising:

• an ink store,
• at least one printing head provided with a plurality of nozzles,
• at least one supply pump connected to the ink store and configured to supply the printing head with a volumetric flow of ink,
• a heating system configured to heat the ink from the ink store to an ink jetting temperature, wherein the heating system includes a first heating element and a second heating element, and wherein the first heating element is configured to heat ink to a first temperature and the second heating element is configured to heat the ink to a jetting temperature,
• and a control unit,
• wherein the printing head comprises a first pressure sensor and a second pressure sensor, the first pressure sensor being located at a fluid inlet upstream of the nozzles and being configured to detect an inlet pressure, the second pressure sensor located at a fluid outlet downstream of the nozzles and configured to detect an outlet pressure,
• wherein the control unit is configured to retrieve the volumetric flow from the supply pump and the inlet and outlet pressures from the pressure sensors, and wherein the control unit is further configured to calculate an actual flow resistance from the inlet and outlet pressures and the volumetric flow, and
• wherein the control unit is further configured to calculate based on the actual flow resistance a required temperature change of the ink such that a calibrated ink viscosity is obtained, and wherein the control unit is further configured to individually modify a heating temperature of the first heating element and a heating temperature of the second heating element of the heating system in order to modify the ink jetting temperature based on the calculated required temperature change to adjust the ink viscosity.