DETERMINATION OF GEOMETRIC AND KINEMATIC CHARACTERISTICS OF FDM 3D PRINT PROCESS

The process of applying a polymer thermoplastic material in the 3D printing process using the FDM technology (Fused Deposition Modeling) was investigated. The object of study was the discrete layer of the prototype. To determine the geometric parameters, samples were made with a thickness of one nozzle diameter (0.5 mm) of the print head of a 3D printer. The obtained samples were cut into sections of the same width (10 mm), in each section a separate layer of the deposited material was cut off. This made it possible to determine the change in thickness from the initial to the final point of the layer. It turned out that the layer thickness is less than the diameter of the nozzle at the beginning of the movement of the print head, gradually grows and at a certain stage begins to exceed the diameter of the nozzle. The obtained values were from 0.4 to 0.6 mm for a nozzle with a diameter of 0.5 mm. The reason is that at the beginning of the supply of the consumable material there is a highly elastic delay in the reaction of the polymeric material to the pressure in the print head and for a certain period of time this part of the material is not applied to the sample, and then the polymer melt swells. Moreover, with an increase in the nozzle diameter, the effect of these phenomena also increases. Also, the printing process was recorded on a wide-format camera in HD-quality with a frequency of 50 frames/s, which allowed to study the dynamics of the application of consumable polymer thermoplastic material. The results showed a difference in speeds from those specified in the executive code. Moreover, for different designs of kinematic schemes for moving the print head, the deviations of the parameters were different – real values were more than theoretical (set) by 20–50 %, depending on the type of FDM 3D printer. This is due to the difference in the inertial characteristics of the various structures of the kinematic patterns of movement of the print head. The results are the basis for further more detailed study of the influence of the configuration of the forming organs and the design of FDM 3D printers on the spatial printing process.