A review of selective laser melting of aluminum alloys: Processing, microstructure, property and developing trends

Denudation of metal powder layers in laser powder bed fusion processes

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.

Surface texture metrology for metal additive manufacturing: a review

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.

https://iopscience.iop.org/article/10.1088/1361-6501/aa5c4f/pdf

Process defects and in situ monitoring methods in metal powder bed fusion: a review

https://dr.ntu.edu.sg/bitstream/10356/80615/1/Xipeng%20Tan_Materials%20and%20Design%202016.pdf

Selective laser melting of stainless steel 316L with low porosity and high build rates

Investigation into spatter behavior during selective laser melting of AISI 316L stainless steel powder

The invention discloses a powder spreading device and a powder spreading method for selective laser melting (SLM) equipment. The device comprises a powder spreading main body, an auxiliary guide rail linear motor and an auxiliary powder spreading guide motor, wherein the auxiliary guide rail linear motor is used for driving the powder spreading main body to slide on an auxiliary powder spreading guide rail; the inside of the powder spreading main body is partitioned into three segments, namely, a cylindrical segment, a circular arc segment and a conical segment from top to bottom respectively; the cylindrical segment is a powder carrying area; a powder feeding hole is formed between the cylindrical segment and the circular arc segment; the circular arc segment is provided with a powder supply roller; a plurality of dovetail grooves are uniformly formed on the powder supply roller; the excircle of the powder supply roller is tangential to a circular arc on the upper part of the circular arc segment; the powder supply roller is driven to rotate by a servo driving motor; the conical segment is provided with a powder scraping device; the bottom of the conical segment is provided with a powder outlet; the upper end of the powder scraping device is tangential to the excircle of the powder supply roller, and the lower end of the powder scraping device extends out of the powder outlet; gaps are reserved between the lower end of the powder scraping device and the two ends of the powder outlet; the powder scraping device comprises a flexible powder scraping brush. By adopting the powder spreading device and the powder spreading method, quantitative powder supply can be realized, waste of powder is reduced, bidirectional powder spreading can be performed, the SLM molding auxiliary process time is shortened, and the SLM molding efficiency is increased.

Powder spreading device and powder spreading method for selective laser melting (SLM) equipment

The utility model discloses a powder spreading device of SLM equipment. The powder spreading device comprises a powder spreading body, an auxiliary guide rail linear motor and an auxiliary powder spreading guide rail. The auxiliary guide rail linear motor drives the powder spreading body to slide on the auxiliary powder spreading guide rail. The interior of the powder spreading body is divided into three sections, the three sections are the cylindrical section, the circular arc section and the conical section from top to bottom respectively, the cylindrical section is a powder loading region, a powder inlet is formed between the cylindrical section and the circular arc section, a powder supply roller is arranged on the circular arc section, a plurality of dovetail grooves are evenly formed in the powder supply roller, the outer circle of the powder supply roller is tangential to a circular arc on the upper portion of the circular arc section, and the powder supply roller is driven by a servo drive motor to rotate. A powder scraping device is arranged on the conical section, a powder outlet is formed in the bottom of the conical section, the upper end of the powder scraping device is tangential to the outer circle of the powder supply roller, the lower end of the powder scraping device stretches out of the powder outlet, and gaps are reserved between the lower end of the powder scraping device and the two ends of the powder outlet. The powder scraping device comprises a flexible powder scraping brush. The powder spreading device can quantitatively supply powder, reduce waste of powder, spread powder in a two-way mode, shorten time of the SLM forming auxiliary process, and improve SLM forming efficiency.

Song Changhui

Papers

Investigation into spatter behavior during selective laser melting of AISI 316L stainless steel powder

Powder spreading device and powder spreading method for selective laser melting (SLM) equipment

Powder spreading device of SLM equipment