Fused filament fabrication printing process of polymers highly filled with metallic powder: a significant influence of the nozzle radiation on the substrate temperature

Extending fused filament fabrication process to feedstock materials used in metal injection molding could be a solution to produce the so-called green part. Nevertheless, process conditions could lead to low mechanical properties partly due to a lack of adhesion between the filament and the substrate. Thus, it is important to estimate correctly the temperature at the substrate interface induced by the filament deposition. Knowing that the extrusion printhead is a relative massive steel part moving at a small distance of the substrate, we have determined the radiative effect of nozzle passages on the temperature surface of the substrate. For that, we inserted thermocouples having a diameter of 0.25 mm under the substrate surface at a depth of 0.45 mm. Thermocouples measured an increase of temperature between 1.1 and 1.4 °C depending on the controlled nozzle and substrate temperatures. A 2D finite-difference model allows determining a significant increase of the substrate temperature at the surface varying between 3.5 and 5 °C depending on processing conditions. This increase of interface temperature, which is favorable to the adhesion of the filament to another one, can be advantageously considered.