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316 L stainless steel alloy is potentially the most used material in the selective laser melting (SLM) process because of its versatility and broad fields of applications (e.g. medical devices, tooling, automotive, etc.). That is why producing fully functional parts through optimal printing configuration is still a key issue to be addressed. This paper aims to present an entirely new framework for simultaneously reducing surface roughness (SR) while increasing the material processing rate in the SLM process of 316L stainless steel, keeping fundamental mechanical properties within their allowable range.

Considering the nonlinear relationship between the printing parameters and features analyzed in the entire experimental space, machine learning and statistical modeling methods were defined to describe the behavior of the selected variables in the as-built conditions. First, the Box–Behnken design was adopted and corresponding experimental planning was conducted to measure the required variables. Second, the relationship between the laser power, scanning speed, hatch distance, layer thickness and selected responses was modeled using empirical methods. Subsequently, three heuristic algorithms (nonsorting genetic algorithm, multi-objective particle swarm optimization and cross-entropy method) were used and compared to search for the Pareto solutions of the formulated multi-objective problem.

A minimum SR value of approximately 12.83 μm and a maximum material processing rate of 2.35 mm³/s were achieved. Finally, some verification experiments recommended by the decision-making system implemented strongly confirmed the reliability of the proposed optimization methodology by providing the ultimate part qualities and their mechanical properties nearly identical to those defined in the literature, with only approximately 10% of error at the maximum.

To the best of the authors’ knowledge, this is the first study dealing with an entirely different and more comprehensive approach for optimizing the 316 L SLM process, embedding it in a unique framework of mechanical and surface properties and material processing rate.

The effect of processing parameters on the microstructure of steel produced by laser-based powder bed fusion (LPBF) is a recognized opportunity for property design through microstructure control. Because the LPBF generates a textured microstructure associated with high anisotropy, it is of interest to determine the fabrication plane that would generate the desired property distribution within a component.

The microstructure of 316 L produced by LPBF was characterized experimentally (optical, scanning electron microscopy, glow discharge emission spectrometry and X-ray diffraction), and a finite element method was used to study the microstructure features of grain diameter, grain orientation and thermal parameters of cooling rate, thermal gradient and molten pool dimensions.

The computational tool of Ansys Additive was found efficient in reproducing the experimental effect of varying laser power, scanning speed and hatch spacing on the microstructure. In particular, the conditions for obtaining maximum densification and minimum fusion defects were consistent with the experiment, and the features of higher microhardness near the component’s surface and distribution of surface roughness were also reproduced.

To the best of the author’s knowledge, this paper is believed to be the first systematic attempt to use Ansys Additive to investigate the anisotropy of the 316 L SS produced by LPBF.

The purpose of this paper is to outline some key aspects such as material systems used, phenomenological and statistical process modeling, techniques applied to monitor the process and optimization approaches reported. All these need to be taken into account for the ongoing development of the SLM technique, particularly in health care applications. The outcomes from this review allow not only to summarize the main features of the process but also to collect a considerable amount of investigation effort so far achieved by the researcher community.

This paper reviews four significant areas of the selective laser melting (SLM) process of metallic systems within the scope of medical devices as follows: established and novel materials used, process modeling, process tracking and quality evaluation, and finally, the attempts for optimizing some process features such as surface roughness, porosity and mechanical properties. All the consulted literature has been highly detailed and discussed to understand the current and existing research gaps.

With this review, there is a prevailing need for further investigation on copper alloys, particularly when conformal cooling, antibacterial and antiviral properties are sought after. Moreover, artificial intelligence techniques for modeling and optimizing the SLM process parameters are still at a poor application level in this field. Furthermore, plenty of research work needs to be done to improve the existent online monitoring techniques.

This review is limited only to the materials, models, monitoring methods, and optimization approaches reported on the SLM process for metallic systems, particularly those found in the health care arena.

SLM is a widely used metal additive manufacturing process due to the possibility of elaborating complex and customized tridimensional parts or components. It is corroborated that SLM produces minimal amounts of waste and enables optimal designs that allow considerable environmental advantages and promotes sustainability.

The key perspectives about the applications of novel materials in the field of medicine are proposed.

The investigations about SLM contain an increasing amount of knowledge, motivated by the growing interest of the scientific community in this relatively young manufacturing process. This study can be seen as a compilation of relevant researches and findings in the field of the metal printing process.

The purpose of this paper is to explore the possibility of producing Cu-based shape memory alloys (SMA) by means of direct metal laser fabrication (DMLF).

The fabrication approach consists of the combination of laser melting of a metallic powder with heating treatment in a controlled inert atmosphere. Three prospective Cu-Al-Ni alloy compositions were tested, and the effects of laser power, as well as laser exposure time, were verified.

All the processed materials were found to attain microstructures and phase change transformation temperatures typical of this type of SMA.

Further development of this technique will allow for fabrication of large elements with considerable shape memory effect, which are currently not viable due to high cost of nitinol.

This work showed a proof of concept toward the development of DMLF-based additive manufacturing of near net shape components of Cu-based SMAs from elemental powders.

The purpose of this paper is to study the effect of different parameters (layer thickness, jetted binder volume per layer and type of binder and temperature) on the mechanical properties of parts made with an experimental 3D printing (3DP) process. This 3DP device built for this project is based on the spiral growth manufacturing (SGM) device previously introduced by Hauser et al. at The University of Liverpool. It differs from the common 3DP in that it generates the different parts using only one rotating piston instead of two non‐rotating ones.

Several parts are produced using this device according to an experimental design, repeating each run three times. The experimental machine is able to make every part needed without major issues, demonstrating that it is possible to build a functional device using common and standard components.

Experimental analysis of the printed parts shows that the layer thickness has the highest effect on apparent density, hardness and fracture strength of the parts made.

Empirical information is provided about mechanical behavior (e.g. apparent density, hardness and fracture strength) of parts made under different processing factors (e.g. binder type, layer thickness, quantity of binder and chamber temperature) using a SGM‐based 3DP experimental device.

In medical applications, it is crucial to evaluate the geometric accuracy of rapid prototyping (RP) models. Current research on evaluating geometric accuracy has focused on identifying two or more specific anatomical landmarks on the original structure and the RP model, and comparing their corresponding linear distances. Such kind of accuracy metrics is ambiguous and may induce misrepresentations of the actual errors. The purpose of this paper is to propose an alternative method and metrics to measure the accuracy of RP models.

The authors propose an accuracy metric composed of two different approaches: a global accuracy evaluation using volumetric intersection indexes calculated over segmented Computed Tomography scans of the original object and the RP model. Second, a local error metric that is computed from the surfaces of the original object and the RP model. This local error is rendered in a 3D surface using a color code, that allow differentiating regions where the model is overestimated, underestimated, or correctly estimated. Global and local error measurements are performed after rigid body registration, segmentation and triangulation.

The results show that the method can be applied to different objects without any modification, and provide simple, meaningful and precise quantitative indexes to measure the geometric accuracy of RP models.

The paper presents a new approach to characterize the geometric errors in RP models using global indexes and a local surface distribution of the errors. It requires minimum human intervention and it can be applied without any modification to any kind of object.

The purpose of this paper is to present results of an investigation, where the elastic tensor based on the engineering constants of sinterized Nylon 12 is characterized and is modeled considering a transversely isotropic behavior as a function of apparent density (relative mass density).

The ultrasound propagation velocity measurement through the material in specific directions by means of the pulse transmission method was used, relating the elastic tensor elements to the phase velocity magnitude through Christoffel's equation. In addition conventional uniaxial tensile tests were carried out to validate the used technique. Laser sintering of Nylon 12 powder (Duraform PA) has been performed at different laser energy densities, fabricating cube‐shaped coupons as well as dogbone flat coupons, using an SLS 125 former DTM machine.

Correlations for each one of the Young moduli, Shear constants and Poisson's ratios, presenting an exponential behavior as a function of the sintering degree, were generated. In addition, as the apparent density reaches a maximum value of 977 kg/m³ at an energy density of 0.032 J/mm², the material behaves in an almost isotropic form, presenting average values for the Young modulus, Shear modulus and Poisson's ratio corresponding to 2,310 MPa, 803 MPa and 0.408, respectively.

The research is limited only to one type of material within the elastic range. Validation of the Young modulus measured along one direction only is performed using a tensile test machine, due to the difficulties in evaluating Poisson's ratios and Shear moduli using conventional tests.

The results presented can be applied to virtual design and evaluating processes such as finite element analysis.

The paper incorporates detailed information regarding the complete elastic characteristics of Nylon 12, including additional measurements of the Shear moduli and Poisson's ratios not studied previously.

The purpose of this paper is to compare the results from mechanical testing with measurements of surface-dependent properties performed on polyamide parts made by selective laser sintering (SLS) to assess a possible correlation between them.

Fabrication of Nylon 12 (Duraform PA®) samples using different laser power levels and their characterization by tensile testing, roughness and Raman scattering measurements.

Among the surface methods investigated, the results from Raman spectroscopy are the best ones, but methods dependent on surface analysis are not really suitable as indicators of the mechanical properties. The correlation coefficients for linear fitting obtained when the normalized results of mechanical properties are plotted against the surface properties are too low. Furthermore, the ambiguity between surface and mechanical data makes it impossible to use these surface properties for prediction purposes in the industrial environment.

Quantitative evaluation and correlation between mechanical properties and surface properties of SLS-made samples.

The purpose of this paper is to characterize polyamide parts prepared by the SLS process using techniques that are dependent on surface properties and compare the results to density measurements in order to assess which technique better reflects the degree of densification achieved using different laser power levels.

Fabrication of Nylon 12 (Duraform PA) samples and their characterization by apparent density measurements, perfilometry, Raman spectroscopy, scanning electron microscopy, specific surface area and contact angle measurements.

Methods dependent on surface analysis are not suitable indicators of the degree of sample densification. Among the surface methods, the results from Raman spectroscopy are the ones with the best performance. Incipient sintering of the superficial layers and raw material powder on the surface, inherent to the parts made by the SLS process, strongly interfere with the characterization.

Quantitative comparison of a number of surface probing methods for monitoring densification of SLS parts. Characterization of sample surfaces with and without raw material powder.

Poland’s syndrome patients often seek medical interventions to improve their aesthetic appearances. Design and manufacturing technologies make it possible to produce custom-made implants for such medical conditions. The purpose of this study was to compare the 3D digital geometries that were designed using Magics and Geomagic^® Freeform^® for two anonymous case studies of Poland’s syndrome patients.

Computed tomography data were acquired and processed in Mimics^® to isolate the pectoralis muscles in STL file format. STL files were imported into Magics and Geomagic^® Freeform^® to design 3D digital geometries. Thereafter, comparative analyses were performed of the respective 3D digital geometries.

The angle between the vertical and oblique planes for both sides of the thorax was 6.5° for the female and 14° for the male. The surface areas and volumes of the geometries for the female were smaller than the male. Deviation analyses between the healthy side and reconstructed side of a thorax showed that 73 per cent of the test points for Magics and 78 per cent for Geomagic^® Freeform^® fell in the nominated tolerance region of >−5 and <+5 mm for the female. For the male, it was 83 per cent for Magics and 88 per cent for Geomagic^® Freeform^®.

Geomagic^® Freeform^® provides a more versatile design environment; however, the STL editor Magics may be an option to design 3D geometries for less intricate and less contoured implants.

This was a first attempt to compare the 3D geometries for Poland’s syndrome designed with an STL editor to those designed with a computer-aided design program.