We have developed an additive manufacturing process that uses an upward-directed laser to fuse a monolayer of powder onto a substrate through a clear surface. The process is then repeated to build a hanging part layer by layer, by replenishing powder on the glass, or moving to a second plate with a different powder. This is enabled by first coating the upper surface of the glass with an aerosol release agent. This agent both captures a uniform sheet of powder and prevents its adhesion to the glass during sintering. Our process eliminates the need for a large powder bed as well as allows the sintering of different powders in a single layer. At present, this process has been found to be functional with thermoplastic powders, as well as curable resins. 

        The inverted nature of this process allows for direct monitoring and observation of the part as it is being printed, to ensure any defects are caught early in the process. Additionally, passive material that previously acted only as support is no longer necessary, reducing the amount of powder that needs to be exposed to a heated environment. Furthermore, we have found that direct compression of the monolayer prior to processing has a direct effect on layer strength. This enables the part to have an artificially weaker region to enable failure predictions, or to be uniformly more robust. 

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Project Participants:

         John Whitehead, Hod Lipson​

Publications:

• Whitehead, J., Lipson, H., (2020) Inverted Multi-Material Laser Sintering, Additive Manufacturing
• Whitehead, J., Lipson, H., (2022) Multi-Process Printing Combining Powder and Resin Based Additive Manufacturing, Additive Manufacturing Letters
• Whitehead, J., Lipson, H., (2022) Embedding Components During Laser Sintering, Additive Manufacturing Letters

Press:

     Columbia Engineering