Fabrication of Metallic Products Using Digital Light Processing-Based Additive Manufacturing: A Review

Direct 3D printing of green bodies and indirect 3D printing for assisting a casting process represent two promising applications of additive manufacturing (AM) based on digital light processing (DLP) for creating high-precision metallic components. Since direct 3D printing is still limited to specific materials, like copper and stainless steel, there is a need to expand this technology to other alloys. The ability to scale it up is further hampered by issues in preprocessing, printing, and post-treatment. This review discusses the complete process chain and applications of DLP in detail. Subsequently, some challenges, such as scattering and residual char, are identified as the remaining obstacles in the current DLP technology. To increase DLP's applicability to high-value industries, a summary of solutions, like preparation of refractive index-tuned slurries, a method to assist in finding printing parameters, and using nanosize powders in mixed slurries, is elucidated. Details of the future research directions pertaining to the method for utilizing carbon-free photopolymer binder, multistage debinding-sintering cycles, and incorporating machine-learning-assisted real-time monitoring to achieve defect-free, industrial-scale production are mentioned. This work provides a template to fully realize DLP-AM's potential as a flexible, effective platform for advanced casting workflows and various metallic material fabrication.