Inverted Printing ProcessI developed a novel laser sintering process that replaces the traditional powder-bed setup with a single powder layer coated onto a glass substrate. This upper surface of this piece of glass is first coated with a monolayer of material. A flat print surface is then pressed onto the top surface of this powder. A laser is shined up through the bottom of the glass, selectively heating and fusing some of this material layer to the print surface. Finally, the print surface is raised with the fused material, the glass can be recoated, and the process can repeat, with new powder layers being fused to the existing print. This novel process requires less material than a standard selective laser sintering machine, and the piece can be observed during the entire print cycle due to the lack of surrounding, unfused powder.
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Multi-Material PrintingIn addition to less material usage and the ability to observe the part during the printing process, this setup enables easy multi-material printing. This is accomplished by simply changing the material powder coated onto the glass between laser cycles. When the print surface is again pressed to the unfused powder layer, the laser can either fuse material in the same layer as the previously fused material or on top of the previous layer. Here, this is demonstrated using thermoplastic polyurethane (white) and Nylon 12 (black).
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Multi-Process PrintingTo further expand the capabilities of the inverted printing process, additional materials were added to increase functionality. One such material was laser curable resin. Instead of recoating the glass with a secondary powder, an additional glass pane was added to the printing process. The upper surface of this pane was coated with a thin layer of stereolithography resin, much like a standard I-SLA printer. The print surface can then be moved between the powder glass and the resin glass, with material from each being selectively fused into the print. This larger range of materials allows greater control over aspects such as part strength, conductivity and porosity.
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Inverted Sintering EmbeddingIn traditional LS printing processes, the use of a powder-filled print bed prevents users from embedding components during the printing process. This is due to the stacked surrounding regions of unfused powder. However, as the ILS process only uses a single layer of unfused material at a time, embedding objects becomes much simpler. This can be done by printing a few layers to create a chamber for a component to be adhered in to. The printing process can then be paused, the object can be inserted, and the process can be continued to cover over the chamber and fully conceal the embedded part.
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Related Links
- Inverted Laser Sintering Systems For Fabrication Of Additively-Manufactured Parts, US Patent App. 16/784,729 (2019)
- Inverted multi-material laser sintering, Additive Manufacturing (2020)
- Multi-Process Printing Method Combining Powder and Resin Based Additive Manufacturing, Additive Manufacturing Letters (2022)
- Embedding Components During Laser Sintering, Additive Manufacturing Letters (2022)
- 3D Printing Industry Awards Innovation of the Year 2021, Runner-Up