| Abstract [eng] |
During this work a polyvinylidene fluoride / barium titanate composite 3D printing filament was fabricated, with target diameter 1.75mm and accuracy of ±0.1mm. The used equipment included a desktop filament extrusion machine (Noztek Touch), a cooling fan array and a pulling system. It was found that accurate filament diameter could be obtained by using an oversized die of 2.75mm and, with the use of adjustable pulling speed, obtain the correct diameter. Special attention was given to the pulling system electronics, the stepper driver controller was redesigned and control software was developed for fine and precise control. The extruder was tested with polylactic acid pellets and PVDF/ BaTiO3 pellets and powder to produce pure PLA filament, pure PVDF filament and PVDF/ BaTiO3 filament of 3wt% and 9wt% concentration. Extruder temperature was stair stepped at 235°C and 225°C and speed was maintained stable at 25 RPM. It was determined that pelletizing and remelting the produced filament resulted in better material flowability and processability through the extruder and more stable diameter was achieved. The mean diameter value for 9wt% PVDF/ BaTiO3 filament was 1.82mm, with process capability indices of Cp=2.6 and Cpk=0.67. The produced PVDF filament was used in a Prusa i3 MK3S+ FDM printer. No obstruction of the nozzle of 0.4mm was observed while printing at 250°C. A heated bed and Dimafix adhesive were used to aid bed adhesion and prevent warping. Fully 3D printed specimen was not obtained due to blob artifacts on the print surface, which eventually resulted in excessive accumulation of material on the nozzle tip and prevented interlayer bonding. |
