Investigation of the deposition velocity related temperature deviations for high temperature materials in the FDM process

With the Fused Deposition Modeling (FDM), an additive manufacturing process, three-dimensional thermoplastic components can be manufactured. For this, a thermoplastic polymer in filament form is fed into a heated nozzle, where it is molten. Through specific movements of the nozzle or the building platform in the x-y-plane the molten polymer is deposited in a defined way onto the building platform or an already existing component structure. This is done layer by layer until the component is completed. As with new demands the material market for the FDM process has grown over the past years, high performance materials (PEEK, PPSU etc.) gain importance. As these materials are processed at high temperatures new effects have to be considered. One of these effects is the outlet temperature of the material coming from the nozzle. This temperature has a significant effect on the welding between the layers and therefore on the mechanical properties. This publication presents the results of the temperature measurement inside a nozzle of the machine GEWO HTP260 with different set temperatures. Also, a simulation of the temperature field inside the nozzle is conducted for three materials. The results show that with different deposition velocities the average outlet temperature of the material is varying. In the experimental investigations the influence of the temperature deviations on the weld seam strength are shown. In a second step the set temperature is adapted based on the simulation results to reach the desired output temperature. The effect of the temperature adaption on the weld seam strength is then analyzed. With these results, users can consider whether an adaption of the set temperature depending on the deposition velocity is necessary to assure a constant output temperature while taking the mechanical properties into account.