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Journal ArticleDOI

Surface roughness analysis, modelling and prediction in selective laser melting

01 Apr 2013-Journal of Materials Processing Technology (Elsevier)-Vol. 213, Iss: 4, pp 589-597
TL;DR: In this paper, a new mathematical model is developed to include the presence of particles on top surfaces, in addition to the stair step effect, for the accurate prediction of surface roughness.
About: This article is published in Journal of Materials Processing Technology.The article was published on 2013-04-01. It has received 641 citations till now. The article focuses on the topics: Surface roughness & Surface finish.
Citations
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Journal ArticleDOI
TL;DR: A review of the emerging research on additive manufacturing of metallic materials is provided in this article, which provides a comprehensive overview of the physical processes and the underlying science of metallurgical structure and properties of the deposited parts.

4,192 citations


Cites methods from "Surface roughness analysis, modelli..."

  • ...The average surface roughness (Ra) is numerically calculated as [194]:...

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  • ...2(a)–(e) shows the SEM images of the alloy powders produced by different processes....

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  • ...SEM, X-ray CT and SRlT can accurately measure shape, size and distribution of very small pores....

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  • ...Scanning electron microscopy (SEM), X-ray and computed tomography (CT) are used to examine the shape and the surface morphology of the powder particles [43]....

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  • ...16(b) shows a scanning electron microscope (SEM) [189] image of a lack of fusion defect that is about 100 mm in size....

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Journal ArticleDOI
TL;DR: In this article, the authors map available additive manufacturing methods based on their process mechanisms, review modelling approaches based on modelling methods and identify research gaps and implications for closed-loop control of the process.
Abstract: Additive manufacturing is a technology rapidly expanding on a number of industrial sectors. It provides design freedom and environmental/ecological advantages. It transforms essentially design files to fully functional products. However, it is still hampered by low productivity, poor quality and uncertainty of final part mechanical properties. The root cause of undesired effects lies in the control aspects of the process. Optimization is difficult due to limited modelling approaches. Physical phenomena associated with additive manufacturing processes are complex, including melting/solidification and vaporization, heat and mass transfer etc. The goal of the current study is to map available additive manufacturing methods based on their process mechanisms, review modelling approaches based on modelling methods and identify research gaps. Later sections of the study review implications for closed-loop control of the process.

984 citations


Cites background from "Surface roughness analysis, modelli..."

  • ...Giovanni et al. [61] investigated the surface roughness and morphology in SLM parts....

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  • ...Those structures need to be built frommetal; therefore focus is given to processes, such as SLS/SLM, DMD and EBM for industrial uses....

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  • ...The operating principle is really close to the SLS/SLM process, albeit lacking in a powder bed; instead powder is fed by a number of nozzles (usually 3) directly to the processing head, similar to that of LENS....

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  • ...Selective laser melting (SLM) Selective laser melting is a process similar to SLS; the two are instantiations of the same concept but differ in technical details....

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  • ...An interesting approach was presented by Cho et al. [48], modelling the SLA process Table 2 AM modelling approaches categorized according to modelling method Process Modelling method Type Name Analytical Numerical Empirical Laser-based (polymerization) SLA [25–33] [34, 35] [36–49] Laser-based (melting) SLS [50] [51–58] [59] SLM [60, 61] [51, 52, 60, 62, 63] DMD [56] LPD [64, 65] SLC [55, 66, 67] Extrusion (thermal) FDM [57, 68–72] [68, 72–78] [58, 79, 80] Material jetting 3DP [65] [81, 82] Adhesive LOM [33] Electron beam EBM [83–87] via a genetic algorithm model in order to determine the optimal process parameters (which include layer thickness, hatch spacing and hatch overcure) that would yield the minimum part build error....

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Journal ArticleDOI
TL;DR: In this article, the service properties of AM parts are described, including physical, mechanical, optical and electrical properties, and an additive manufacturability index is proposed, based on the seven categories of ISO/ASTM AM categories.

636 citations

Journal ArticleDOI
TL;DR: A comprehensive analysis of surface texture metrology for metal additive manufacturing has been performed in this paper, where the results of this analysis are divided into sections that address specific areas of interest: industrial domain; additive manufacturing processes and materials; types of surface investigated; surface measurement technology and surface texture characterisation.
Abstract: A comprehensive analysis of literature pertaining to surface texture metrology for metal additive manufacturing has been performed. This review paper structures the results of this analysis into sections that address specific areas of interest: industrial domain; additive manufacturing processes and materials; types of surface investigated; surface measurement technology and surface texture characterisation. Each section reports on how frequently specific techniques, processes or materials have been utilised and discusses how and why they are employed. Based on these results, possible optimisation of methods and reporting is suggested and the areas that may have significant potential for future research are highlighted.

537 citations


Cites background from "Surface roughness analysis, modelli..."

  • ...…L. Blunta, R.K. Leachb, J.S. Taylorc a EPSCRC Centre for Innovation in Advanced Metrology, University of Huddersfield, UK b Manufacturing Metrology Team, Faculty of Engineering, University of Nottingham, UK c Center for Precision Metrology, University of North Carolina at Charlotte and Lawrence...

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Journal ArticleDOI
TL;DR: In this paper, a review of the literature and the commercial tools for insitu monitoring of powder bed fusion (PBF) processes is presented, focusing on the development of automated defect detection rules and the study of process control strategies.
Abstract: Despite continuous technological enhancements of metal Additive Manufacturing (AM) systems, the lack of process repeatability and stability still represents a barrier for the industrial breakthrough. The most relevant metal AM applications currently involve industrial sectors (e.g., aerospace and bio-medical) where defects avoidance is fundamental. Because of this, there is the need to develop novel in-situ monitoring tools able to keep under control the stability of the process on a layer-by-layer basis, and to detect the onset of defects as soon as possible. On the one hand, AM systems must be equipped with in-situ sensing devices able to measure relevant quantities during the process, a.k.a. process signatures. On the other hand, in-process data analytics and statistical monitoring techniques are required to detect and localize the defects in an automated way. This paper reviews the literature and the commercial tools for insitu monitoring of Powder Bed Fusion (PBF) processes. It explores the different categories of defects and their main causes, the most relevant process signatures and the in-situ sensing approaches proposed so far. Particular attention is devoted to the development of automated defect detection rules and the study of process control strategies, which represent two critical fields for the development of future smart PBF systems.

505 citations


Cites background from "Surface roughness analysis, modelli..."

  • ...Surface defects are also produced by the balling effect, which prevents the achievement of smooth surfaces (Li et al., 2012, Strano et al., 2013; Townsend et al., 2016)....

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  • ...The surface finishing depends on the surface orientation with respect to the growth direction (Fox et al., 2016, Strano et al., 2013)....

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References
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Book
12 Mar 2014
TL;DR: In this paper, the effect of reflectivity of the surface, when a pure, monochromatic laser (6) is used, is remedied by the simultaneous application of a relatively shorter wavelength beam (1).
Abstract: In the laser treatment of a workpiece (9), e.g. for surface hardening, melting, alloying, cladding, welding or cutting, the adverse effect of reflectivity of the surface, when a pure, monochromatic laser (6) is used, is remedied by the simultaneous application of a relatively shorter wavelength beam (1). The two beams (1)(5) may be combined by a beam coupler (4) or may reach the workpiece (9) by separate optical paths (not shown). The shorter wavelength beam (1) improves the coupling efficiency of the higher- powered laser beam (5).

1,539 citations

PatentDOI
TL;DR: In this paper, a method of fabricating a fully dense, three dimensional object by direct laser sintering is disclosed, in which a degased powder layer is dispensed over a target surface and a beam of directed energy melts metallic powder in order to form a solid layer cross section.
Abstract: A method of fabricating a fully dense, three dimensional object by direct laser sintering is disclosed (flow chart). In a chamber (evacuated) with a partial pressure atmosphere, a degased powder layer is dispensed over a target surface and a beam of directed energy melts metallic powder in order to form a solid layer cross section. Another layer of powder is deposited and melted, along with a portion of the previous layer. The energy beam typically is in the form of a laser, scanning along a path resembling a parametric curve or another, arbitrary piecewise parametric curve (vector scan). In another embodiment, the previous layer is not remelted, thus creating an oxide film that acts as a clean stop to prevent unwanted downward growth.

723 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the selective laser melting of Inconel 625 using an Nd:YAG pulsed laser to produce thin wall parts with an emphasis on attaining parts with minimum top surface and side surface roughness.
Abstract: Purpose – Obtaining the required part top surface roughness and side roughness is critical in some applications. Each of these part properties can often be improved to the detriment of the other during selective laser melting (SLM). The purpose of this paper is to investigate the selective laser melting of Inconel 625 using an Nd:YAG pulsed laser to produce thin wall parts with an emphasis on attaining parts with minimum top surface and side surface roughness.Design/methodology/approach – A full factorial approach was used to vary process parameters and identify a usable Inconel 625 processing region. The effects laser process parameters had on the formation of part surface roughness for multi‐layer parts were examined. Processing parameters that specifically affected top surface and side roughness were identified.Findings – Higher peak powers tended to reduce top surface roughness and reduce side roughness as recoil pressures flatten out the melt pool and reduce balling formation by increasing wettabilit...

341 citations

Journal ArticleDOI
TL;DR: In this article, a numerical simulation of the heat flow equation has been performed and compared with experimentally obtained titanium plates, which allowed to obtain a process map of the sintering process.

332 citations