Development of Sub-Surface Laser Additive Manufacturing Process for Liquid Resins

The goal of the present study is to develop original research revolving around plastics-based Laser Additive Manufacturing (LAM) that seeks to improve the current quality, print time, strength, and post-processing needed for LAM. This is accomplished through repurposing a sub-surface laser engraving (SSLE) machine that solidifies bio-resin through thermal polymerization. SSLE machines are traditionally used to create greyscale art pieces that are suspended in a solid crystal block. This is accomplished through focusing the laser below the top surface of the crystal and creating micro-fractures in the material that are around 20 – 30 µm in size. By keeping the same general process of SSLE, but changing what medium the laser interacts with, this experimental research seeks to replace the micro-fractures with micro-solids through laser induced thermal polymerization in resin. A resin with 50% (weight) of Tung oil is considered for its eco-friendliness. An SSLE machine equipped with a diode pumped Nd: YAG laser is customized to focus laser energy at the subsurface of the resin medium. Several advantages are hypothesized for this new additive manufacturing technique including the elimination of strictly defined layer lines, no longer needing a build plate for the part to build from, the absence of support material as any overhangs will be suspended in the uncured resin, enhancement of surface quality, and the improved strength found from a proposed Body Centered Cubic (BCC) lattice structure of the points. In combining these unprecedented advantages, it is expected that the Sub-Surface Laser Additive Manufacturing (SSLAM) would be an industry-leading advancement with a wide range of applications for commercial product development.