Spray printing and vat-photopolymerization hybrid additive manufacturing platform for contactless high-resolution 3D printing

Abstract

This thesis presents the design, implementation, and evaluation of a hybrid additive manufacturing platform that combines spray based thin film deposition with digital light processing (DLP) UV curing. The system was developed as a low cost platform, with a total hardware budget below €1000, while integrating a custom mechanical assembly, pneumatic delivery, and an optically aligned projection unit in a coordinated layer by layer workflow. The hardware platform achieves a mechanical XY resolution of 100 μm with a measured XY misalignment of approximately 60 μm and supports controlled airbrush needle actuation with a 5.2 mm travel range at 0.1 mm resolution. The reconfigured DLP subsystem provides an effective pixel size of approximately 15μm and an irradiance of roughly 54 mW/cm2, enabling localized curing of deposited films. Printing performance was characterized through single line, single material, and multi-material benchmarks. The minimum stable line width produced by the spray deposition process was 0.5 mm, and dimensional tests showed a shrinkage of approximately 2% for features larger than 1-2 mm. Surface quality remained consistent with an average roughness of Ra = 1.01 μm. Multi-material trials demonstrated the feasibility of switching between materials, though interface sharpness remained constrained with measured interface widths greater than 0.5 mm. Together, these results establish a functional hybrid printing method capable of producing thin film structures with controlled geometry, while revealing key limitations related to overspray, alignment drift, material cross contamination, and optical resolution.