Top surface quality research for direct metal laser fabrication

Abstract

Purpose -The purpose of this paper is to describe the stability and properties of the direct metal laser fabrication (DMLF) process, by putting forward top surface quality (TSQ), which could be a unique and crucially important feature compared with traditional manufacturing methods. Design/methodology/approach -Through the systematic and detailed analysis of DMLF process using related theories of additive manufacturing technologies, it was revealed that TSQ was the key factor for controlling the stability of DMLF process and thus tailoring final properties of metallic parts. Only good TSQ can ensure the stability of DMLF process and excellent performance of metal parts in theory.Findings -TSQ was defined as the surface morphology in macro and micro scopes in laser scanning area of unit layers during DMLF, and could be characterized by three key elements: flatness, compactness and cleanliness. The flatness was the significant factor to assure the shaping during DMLF, while the compactness and cleanliness were the decisive factors to assure the final properties of metal part for DMLF. As an example, the typical top surface defects and their contributing factors in DMLF for Cu-based metal powder mixtures were investigated thoroughly according to the proposed definition and requirements. Moreover, the specific controlling methods of TSQ were provided and discussed. Eventually, DMLF of three-dimensional Cu-based metal sample with complicate structure was successfully performed by taking some effective measures for adjusting TSQ parameters. Originality/value -Few comprehensive investigations have been carried out on this topic. The definition and evaluation methods of TSQ for DMLF have been introduced for the first time in the present paper.

Laser Powder Bed Fusion – Materials Issues and Optimized Processing Parameters for Tool steels, AlSiMg‐ and CuCrZr‐Alloys

“…In spite of the high thermal conductivity, pure copper has the disadvantage of having a low absorption coefficient of about 25% (for irradiation on powder-surface at 1 030-1 080 nm wavelength). While Yang et al [36] was investigating on mixed powder of Cu and CuSn20 in 2012, Lodes et al [37] performed experiments on pure copper by using electron beam melting, thus, reaching a relative part density of up to 99.95%. Laser-facilities of higher power and/or lower wavelength would be necessary to accomplish dense L-PBFfabricated components made of copper.…”

“…[32,34,35] However, the fabrication of parts made of Cu and Cu-alloys has been a subject of numerous studies in recent years. While Yang et al [36] was investigating on mixed powder of Cu and CuSn20 in 2012, Lodes et al [37] performed experiments on pure copper by using electron beam melting, thus, reaching a relative part density of up to 99.95%. Producing via laser device still remains challenging, for several studies on L-PBF of Cu-alloys have been performed since, then, concerning its relative density, mechanical properties, as well as thermal and optical properties.…”

Control of Porosity in Parts Produced by a Direct Laser Melting Process

“…2018, 8, x FOR PEER REVIEW 9 of 17 of deposited layers using powders 2, 3, and 4, the porosity increased with the size of the nonspherical powder mixed with the spherical powder. The variation in porosity densities is mainly caused by the powder packing density [25]. When larger powders with non-spherical morphologies are mixed with spherical powder, numerous pores are generated as a result of the reduced powder packing density.…”

Development of Laser Fusion Printing Machine for Ceramic Teeth Crown

“…Additive Manufacturing (AM), commonly known as 3D Printing, is the generic terms of all of the rapid prototyping or rapid manufacturing technologies which manufacture physical objects by means of adding materials directly on the basis of three-dimensional computer-aided-designed (CAD) model [1]- [8]. At present, AM has been widely using in the fields of defense, aeronautics & astronautics, biology and medicine, motor vehicle, mold, new material developing, individual customization, and so on, which could observably shorten the development period and manufacturing process attributed to its laminated manufacture principle which means that three-dimensional physical object with arbitrary complicated exterior shape or interior structure can be manufactured directly by means of three-dimensional CAD model without any tools and middle process [9] [10] [11] [12].…”