Comparative study of process parameters’ influence on geometric accuracy and relative errors of lightweight compound gear printed by vat. photopolymerization and material extrusion

Abstract

Plastic and polymer composite gears are gaining popularity due to their cost-effectiveness, lightweight properties, and quiet operation compared to metal gears. Additive manufacturing has transformed the production of lightweight gears, impacting their dynamic behavior. However, determining the optimal printing conditions remains a subject of ongoing research. In this study the compound gear for well-zoom filament extruder machine was 3D printed using two different three-dimensional printing techniques, namely vat photopolymerization and material extrusion. Taguchi L9 array was created using 2 factors at 3 levels for selected process parameters of VPP (layer height, exposure time) and MEX (layer height, extruding temperature) using Minitab software, both methods employed a printing orientation of 45°, while all other parameters remained constant. A total of 54 gears were 3D printed, with the focus on identifying the optimal printing process parameters to achieve minimal geometric errors. In this study a new approach of digital microscopy was applied, for sector span measurement and subsequent parameter calculations like base pitch $p_b$, base circular thickness $S_b$, tip diameter $d_a$, root diameter $d_f$, circular pitch $p$ and single pitch deviation $f_{\mathrm{pt}}$. The study, identified optimal parameters for VPP include a layer height of 100 μm and an exposure time of 6 s, resulting in relative errors of less than 1.73% in sector span, less than 3.25% in base circular thickness, 1.34% in tip diameter, and 0.09% in root diameter. Similarly, in MEX, a layer height of 100 μm and a printing temperature of 210 °C yield favorable results, with relative errors of less than 0.43% in sector span, less than 1.45% in base circular thickness, 1.42% in tip diameter, and 0.17% in root diameter.