Browsing by Subject "Microscale additive manufacturing"

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    Design and characterization of a coating device to enable multilayer structures in microscale selective laser sintering
    (2023-08) Liao, Aaron; Cullinan, Michael
    The microscale selective laser sintering process (µ-SLS) is an additive manufacturing technique that enables the creation of metal features with sub-5 µm in-plane resolution. In this process, a layer of metal nanoparticle ink is deposited onto a substrate and positioned beneath an optical subsystem with a nanopositioning stage. Using a digital micromirror device, a laser is spatially modulated to selectively heat particles in desired regions to cause sintering. The substrate is then moved to a coating station where the sintered features are recoated by a meniscus-guided coating process. The slot-die coating process was originally proposed and adopted as the recoating method for this critical step. Due to challenges with depositing consistent ink thickness across the recoated part and limitations with the volumetric resolution, a new meniscus-guided approach inspired by blade coating has been implemented and is able to recoat parts with layer thicknesses of less than 1 µm. Additionally, the multilayer performance of µ-SLS has improved significantly, now able to produce fully sintered layers up to a depth of 50 microns of material.
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    Nanoparticle bed dispense and global translation mechanisms in a microscale selective laser sintering process
    (2018-10-04) Behera, Dipankar; Cullinan, Michael
    This thesis presents a design validation and experimental analysis of a novel nanoparticle bed dispense mechanism and the translation system of a microscale selective laser sintering (μ-SLS)tool. A comprehensive study of a slot die coating based technique used for the nanoparticle bed spreading in a μ-SLS process is done. Coating models for single layer and multiple layer coating have been discussed. Coating uniformity tests at different coating gaps and speeds has been shown. The sintering experiments for single layer and multiple layer show the features which can be achieved and the critical areas where further work needs to be done. pre-sintering and post-sintering paramters like the partial drying of the NP ink bed and the washing off process have been discussed in this thesis as well. In addition to the coating and sintering process, the resolution and repeatability experiments of the global positioner have been done to analyze the positioning capabilities of a linear motor guided by air bearing rails.