Laser direct metal deposition process of thin-walled parts using variable spot by inside-beam powder feeding

Abstract

PurposeThe purpose of this paper is to improve the forming efficiency and quality of unequal-width parts fabricated by laser direct metal deposition technology, some experiments were designed.Design/methodology/approachA new method by varying laser spot was adopted to fabricate unequal-width single track using one scanning rather than multi-track overlapping in the way of the inside-beam powder feeding, and the thin-walled parts were fabricated layer by layer. The theoretical model among layer thickness of z-axis, height of single track and the section curve order of single track was established.FindingsThe top surface unevenness of the thin-walled parts could be compensated automatically within the laser defocusing ranges from −2.5 to −5 mm and from 0.5 to 2.5 mm. The growth rate with the large width/height ratio was more than the small ratio, while the set height of the single track was uniform. The problem of non-uniform growth rate could be solved based on a stepped single-track method. The thin-walled parts with the smooth top surface was fabricated layer by layer which had a continuously variable width from 1 to 3 mm by splicing the laser defocusing range.Practical implicationsThe shapes of the to-be-fabricated parts affect variable laser spot process in practical applications. For example, it will be difficult to apply variable laser spot process on the parts with the hole features.Originality/valueThis paper provided a guidance for forming unequal-width parts by laser direct metal deposition based on the inside-beam powder feeding.