| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 106 === In this thesis, a selective laser melting (SLM) system based on a powder bed fusion platform with an expended laser beam is constructed. The effect of parts deformation by Raster Scan Strategy and 3 kinds of 2-zone Scan strategy (non-refill, refill and refill with different power of 2nd scan track) are investigated. First, multi-track structures were formed by 74W CW-laser and optimized scan speed. In each of the Scan Strategy, different track-overlapping rate were studied, and the best parameters of each strategy is adopted to fabricate multi-layer structures. In multi-layer experiment, morphology of the cross-section and the height of the parts were investigate. Finally, the over-hanging parts is fabricated by different angle of the overhanging surface.
According to the experiments result, Raster Scan Strategy is bad for the parts density but its build accuracy is quite good. In 2-zone strategy, refill strategy can’t build over-hanging parts as the thickness of each layer is much more than the design value, and the non-fill strategy has more dense part compare to the Raster Scan Strategy. We found that 45̊ of the parts has serious warp on the top of the overhanging surface.
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