The study compared and investigated the surface roughness of the samples produced by hybrid manufacturing and 3D printing. It is aimed to increase the surface quality by removing the rough surface caused by additive manufacturing by machining.
Figure 2 shows the surface roughness of the samples with a layer thickness of 0.2 mm in the z-direction (direction perpendicular to the layers) in different materials, production techniques, and production temperature values. The highest surface quality at 190°C was listed as produced with PLA carbon fiber hybrid, produced with PLA hybrid manufacturing, produced in PLA 3D printer, and produced in PLA carbon fiber 3D printer, respectively. It is seen that hybrid manufacturing improves the surface quality in both PLA and carbon fiber-reinforced PLA at 190°C printing temperature. It was determined that the surface quality increased more in the hybrid manufacturing of carbon fiber-reinforced PLA material than in PLA material. The surface qualities for the samples grown at 210°C were determined as those produced by PLA carbon fiber hybrid, PLA hybrid, PLA carbon fiber 3D printed, and PLA 3D printed, respectively. The hybrid manufacturing method with carbon fiber-reinforced PLA material has significantly improved both PLA production and surface quality at a printing temperature of 210°C. When the surface qualities were compared to see the effect of printing temperature increase on the surface quality, it was seen that the surface quality decreased in PLA material and 3D printer with increasing temperature from 190°C to 210°C, while the surface quality increased with the hybrid. Carbon fiber-reinforced PLA has improved surface quality in 3D printing and hybrid.
Figure 3 indicates the surface roughness of the samples with a layer thickness of 0.4 mm in the z-direction (direction perpendicular to the layers) in different materials, production techniques, and production temperature values. At 190°C, the surface quality is listed as produced with the highest PLA carbon fiber hybrid, PLA hybrid, PLA 3D printed, and PLA carbon fiber 3D printed, respectively. The hybrid manufacturing with carbon fiber-reinforced PLA material significantly improved both PLA production and surface quality at a printing temperature of 190°C. It has been observed that hybrid manufacturing in PLA production at 210°C temperature significantly improves surface quality, and hybrid manufacturing made with carbon fiber PLA material slightly improves surface quality.
When the surface qualities were compared to see the effect of the temperature increase on the surface quality, it was seen that the surface quality decreased both in 3D printing and hybrid with PLA with increasing temperature from 190°C to 210°C. In the carbon fiber-reinforced PLA, an increase in surface quality was observed in 3D printers, and an increase in roughness was observed in the hybrid. In addition, it was seen that the surface quality improved for all materials and production techniques at both 190°C and 210°C production temperatures, with layer thickness increasing from 0.2 mm to 0.4 mm.
The surface of the produced samples was examined under the optic microscope, and their images were recorded (Fig. 4). It is seen that the irregularities on the layer are reduced with hybrid manufacturing when the samples produced in a 3D printer with a layer thickness of 0.2 mm and with hybrid manufacturing are compared. Considering the 0.4 mm layer thickness, relatively distorted layers are seen in the first layers of the hybrid fabrication sample. It is thought that this may be due to chips adhering to the insert or the nozzle distance being too close. It is observed that the unevenness on the surface increases with the increase of layer thickness from 0.2 mm layer thickness to 0.4 mm thickness.
Figure 5 shows the chipped and uncut surfaces of the samples produced with the 3D printer and hybrid. A smoother surface is obtained by removing the wavy structure on the sawdust surfaces. It was observed that the surface of the samples produced in the 3D printer was quite bad, and the damaged surface was corrected with hybrid manufacturing. Thus, the height differences on the layer surface are minimized.
The changes in the dimensional accuracy of the samples with a layer thickness of 0.2 mm in different materials, production techniques, and temperature values are shown in Fig. 6. At 190°C, the amount of error was listed as the lowest produced by PLA hybrid, produced by PLA 3D printer, produced by PLA carbon fiber hybrid, and produced by PLA carbon fiber 3D printer, respectively. An increase in dimensional accuracy was observed when PLA material was produced with hybrid at a production temperature of 190°C. Similarly, the carbon fiber-reinforced PLA material produced with hybrid slightly increased the dimensional accuracy. At 210°C, the amount of error is listed as the lowest PLA carbon fiber hybrid manufacturing, PLA carbon fiber 3D printed, PLA hybrid produced, and PLA 3D printed, respectively. In both PLA and carbon fiber reinforced PLA production at 210°C printing temperature, An increase in dimensional accuracy has been observed with the hybrid. When the amount of dimensional error was compared to see the effect of temperature increase on dimensional accuracy, it was seen that the amount of error increased with increasing printing temperature from 190°C to 210°C, both in the 3D printer and hybrid manufacturing with PLA material. It was determined that the dimensional error increased in 3D printers with carbon fiber-reinforced PLA but decreased in hybrid.
The changes in the dimensional accuracy of the samples with a layer thickness of 0.4 mm in different materials, production techniques, and temperature values are also seen in Fig. 6. At 190°C production temperature, the amount of error is listed as the lowest PLA carbon fiber produced with hybrid manufacturing, PLA hybrid manufacturing made, PLA 3D printer produced, and PLA carbon fiber 3D printer produced, respectively. While some increase was seen, dimensional accuracy increased significantly with hybrid fabrication in carbon fiber-reinforced PLA production.
The dimensional error at 210°C was listed as the lowest produced in PLA carbon fiber 3D printer, built-in PLA 3D printer, made by PLA carbon fiber hybrid fabrication, and produced by PLA hybrid fabrication, respectively. Hybrid manufacturing did not improve dimensional accuracy in both PLA and carbon fiber-reinforced PLA production at a temperature of 210°C.
When the amount of dimensional error was compared to see the effect of temperature increase on dimensional accuracy, it was seen that the amount of error decreased in PLA material and 3D printer with increasing temperature from 190°C to 210°C but increased in hybrid manufacturing machine. It was determined that the amount of error decreased in 3D printers with carbon fiber-reinforced PLA but increased in hybrid manufacturing. To see the effect of layer thickness increase on dimensional accuracy, dimensional error amounts of samples with different layer thicknesses were compared. With layer thickness increasing from 0.2 mm to 0.4 mm, the amount of error decreased at 190°C production temperature in 3D printers with PLA material, increased in hybrid manufacturing with PLA material, increased in 3D printers with carbon fiber reinforced PLA, and increased in carbon fiber reinforced PLA. It has been observed to decrease hybrid manufacturing with PLA. It was determined that the amount of error decreased in 3D printers with PLA material, increased slightly in hybrid manufacturing with PLA material, fell in 3D printers with carbon fiber reinforced PLA, and increased in hybrid manufacturing with carbon fiber reinforced PLA at 210°C production temperature.
The surface profile change in the z-direction (perpendicular to the layers) of PLA samples produced hybrid with a 3D printer, depending on the layer thickness and production temperature, is shown in Fig. 7. As the layer thickness increases, it is seen that the effect of each ladder shape becomes more pronounced. It has been determined that the product temperature change has almost no impact on the surface profile. The result of hybrid fabrication on the staircase appearance is seen in Fig. 7.