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The purpose of this paper is to develop a methodology to analyze the total sintering energy (TSE) required for manufacturing a part in metal powder-based additive manufacturing (AM) processes and optimize AM processes for minimizing total energy and form errors of AM parts while maximizing part strength.

The paper uses a computational geometry approach to determine the TSE expended for manufacturing a metal AM part. The stereolithography (STL) file of a part is converted into a voxel data structure and the total sintering volume (TSV) is computed from the voxel representation. The TSE is then calculated from the TSV using the material property information of the metal powder.

The TSE of an AM part is calculated for different slice thickness and part orientations, and the correlation of the total energy to these parameters is calculated. Using these correlations, the AM process is optimized to calculate the optimal values of slice thickness and part orientation which would result in lower process energy, lower part form errors and higher part strength.

The methodology presented in this paper provides AM users a roadmap to predict the energy required for manufacturing a part. In addition, the optimization model will allow engineers to manufacture precision parts which satisfy their design specifications with minimal energy expenditure.

This paper presents a unified framework to model the sintering process of fine powders. The framework is based on classical virtual power principle and its corresponding variational principle. Firstly, the classical models of solid state, viscous and liquid phase sintering are reproduced assuming single matter re‐distribution mechanism and using the virtual power principle as the starting point. Then we demonstrate how to obtain the governing equations for microstructural evolution using the variational principle. These provide a common thread through the existing sintering models. Finally a numerical solution scheme is briefly outlined for computer simulation of microstructural evolution using the variational principle as the starting point. The computer simulation can follow the entire sintering process from powder compact to fully dense solid and deal with fully couple multi‐physics processes involving all the possible underlying matter re‐distribution mechanisms. Several examples are provided to demonstrate the deep insights that can be gained into the sintering process by using the numerical tool.

Projection sintering, a system for selectively sintering large areas of polymer powder simultaneously with a high-power projector is introduced. This paper aims to evaluate the suitability of laser sintering (LS) process parameters for projection sintering, as it uses substantially lower intensities, longer exposure times and larger areas than conventional LS.

The tradeoffs in sintering outcomes are evaluated by creating single layer components with varied exposure times and optical intensities. Some of these components were cross-sectioned and evaluated for degree of densification, while the single-layer thickness and the maximum tensile force was measured for the rest.

Shorter exposure times and higher intensities can create thicker and therefore stronger parts than when equal energy is applied over longer exposures. This is different from LS in which energy input (Andrew’s Number) is accepted as a reliable process variable. This difference is likely because significant thermal energy is lost from the sintering region during the exposure time – resulting in reduced peak temperatures. These thermal losses can be offset by imparting additional energy through increased exposure time or light intensity.

Most methods for evaluating LS process parameters, such as the energy melt ratio and Andrew’s Number, estimate energy input from basic process parameters. These methods do not account for thermal losses and assume that the powder absorbs all incident light. These methods become increasingly inaccurate for projection sintering with visible light where exposure times are much higher (>1s) and a larger portion of the light is reflected from the power’s surface. Understanding the appropriate sintering criteria is critical for the development of long-exposure sintering.

A new method of selectively sintering large areas is introduced that could sinter a wider variety of materials by enabling longer sintering times and may increase productivity relative to LS. This work shows that new processing parameters are required for projection sintering as traditional LS process parameters are inadequate.

The purpose of this paper is to evaluate the energy consumed to fabricate nylon parts using selective laser sintering (SLS) and to compare it with the energy consumed for injection molding (IM) the same parts.

Estimates of energy consumption include the energy consumed for nylon material refinement, adjusted for SLS and IM process yields. Estimates also include the energy consumed by the SLS and IM equipment for part fabrication and the energy consumed to machine the injection mold and refine the metal feedstock required to fabricate it. A representative part is used to size the injection mold and to quantify throughput for the SLS machine per build.

Although SLS uses significantly more energy than IM during part fabrication, this energy consumption is partially offset by the energy consumption associated with production of the injection mold. As a result, the energy consumed per part for IM decreases with the number of parts fabricated while the energy consumed per part for SLS remains relatively constant as long as builds are packed efficiently. The crossover production volume, at which IM and SLS consume equivalent amounts of energy per part, ranges from 50 to 300 representative parts, depending on the choice of mold plate material.

The research is limited to material refinement and part fabrication and does not consider other aspects of the life cycle, such as waste disposal, distributed 2 manufacturing, transportation, recycling or use. Also, the crossover volumes are specific to the representative part and are expected to vary with part geometry.

The results of this comparative study of SLS and IM energy consumption indicate that manufacturers can save energy using SLS for parts with small production volumes. The comparatively large amounts of nylon material waste and energy consumption during fabrication make it inefficient, from an energy perspective, to use SLS for higher production volumes. The crossover production volume depends on the geometry of the part and the choice of material for the mold.

This study aims to achieve customized prosthesis for total joint arthroplasty and total hip arthroplasty. Selective laser sintering (SLS) as additive manufacturing could enable small-scale fabrication of customized Ultra High Molecular Weight Polyethylene (UHMWPE) components; however, the processes for SLS of UHMWPE need to be improved.

This paper begins by improving the preheating system of the SLS fabricating equipment and then fabricating cuboids with the same size and cuboids with same volume and different size to study the warpage, demonstrating the effect of the value and uniformity of the preheating temperature on component fabrication. Warpage, density and tensile properties are investigated from the perspective of energy input density. Finally, complicated industrial parts are produced effectively by using optimized technological parameters.

The results show that components can be fabricated effectively after the optimization of the SLS technological parameters i.e. the preheating temperature the laser power the scanning interval and the scanning speed. The resulting warpage was found to be less than 0.1 mm along with the density as 83.25 and the tensile strength up to 14.1 Mpa. UHMWPE sample parts with good appearance and strength are obtained after ascertaining the effect of each factor on the fabrication of the sample parts.

It is very challenging to fabricate UHMWPE sample parts by SLS. This is a new step in the fabrication of customized UHMWPE sample parts.

Selective laser sintering (SLS) is a leading process for developing rapid prototype objects by selectively fusing layers of powder according to numerically defined cross‐sectional geometry. The process has the potential to become an indispensable industrial tool. However, continuous process improvement is necessary. Improved understanding of the parameter effects on the process response is expected to lead to process advances. In this work the analytical problem describing the energy delivery, heat transfer and sintering process along with other pertinent phenomena is studied. Physical experiments and implementation of a numerical simulation are conducted using Bisphenol‐A polycarbonate. The effects of selected parameters on the SLS process response are examined. The primary parameters of interest are the laser power, laser beam velocity, hatch spacing, laser beam spot size and scan line length. This work shows that the secondary process parameters, delay period and number of effective exposures have a significant influence on the process response.

This paper aims to present parametric models to estimate the environmental footprint of the selective laser sintering (SLS)’ production phase, covering energy and resource consumption as well as process emissions. Additive manufacturing processes such as (SLS) are often considered to be more sustainable then conventional manufacturing methods. However, quantitative analyses of the environmental impact of these processes are still limited and mainly focus on energy consumption.

The required Life Cycle Inventory data are collected using the CO2PE! – Methodology, including time, power, consumables and emission studies. Multiple linear regression analyses have been applied to investigate the interrelationships between product design features on the one hand and production time (energy and resource consumption) on the other hand.

The proposed parametric process models provide accurate estimations of the environmental footprint of SLS processes based on two design features, build height and volume, and help to identify and quantify measures for significant impact reduction of both involved products and the supporting machine tools.

The gained environmental insight can be used as input for ecodesign activities, as well as environmental comparison of alternative manufacturing process plans.

This article aims to overcome the current lack of environmental impact models, covering energy and resource consumption as well as process emissions for SLS processes.

Binder jetting is a promising route to produce complex copper components for electronic/thermal applications. This paper aims to lay a framework for determining the effects of sintering parameters on the final microstructure of copper parts fabricated through binder jetting.

The knowledge gained from well-established powder metallurgy processes was leveraged to study the densification behaviour of a fine high-purity copper powder (D₅₀ of 3.4 µm) processed via binder jetting, by performing dilatometry and microstructural characterization. The effects of sintering parameters on densification of samples obtained with a commercial water-based binder were also explored.

Sintering started at lower temperature in cold-pressed (∼680 °C) than in binder jetted parts (∼900 °C), because the strain energy introduced by powder compression reduces the sintering activation energy. Vacuum sintering promoted pore closure, resulting in greater and more uniform densification than sintering in argon, as argon pressure stabilizes the residual porosity. About 6.9% residual porosity was obtained with air sintering in the presence of graphite, promoting solid-state diffusion by copper oxide reduction.

This paper reports the first systematic characterization of the thermal events occurring during solid-state sintering of high-purity copper under different atmospheres. The results can be used to optimize the sintering parameters for the manufacturing of complex copper components through binder jetting.

Selective laser sintering (SLS) is one of the most rapidly growing rapid prototyping techniques (RPT). This is mainly due to its suitability to process almost any material: polymers, metals, ceramics (including foundry sand) and many types of composites. The material should be supplied as powder that may occasionally contain a sacrificial polymer binder that has to be removed (debinded) afterwards. The interaction between the laser beam and the powder material used in SLS is one of the dominant phenomena that defines the feasibility and quality of any SLS process. This paper surveys the current state of SLS in terms of materials and lasers. It describes investigations carried out experimentally and by numerical simulation in order to get insight into laser‐material interaction and to control this interaction properly.

Solid freeform fabrication processes such as three‐dimensional printing (3DP) and selective laser sintering (SLS) produce porous parts. Metal parts produced by these processes must be densified by sintering or infiltration to achieve maximum material performance. New steel infiltration methods can produce parts of standard alloy compositions with properties comparable to wrought materials. However, the infiltration process introduces dimensional errors due to both shrinkage and creep — particularly at the high temperatures required for steel infiltration. Aims to develop post‐processing method to reduce creep and shrinkage of porous metal skeletons.

The proposed process treats porous metal parts with a nanoparticle suspension that strengthens the bonds between particles to reduce creep and sintering shrinkage during infiltration. The process is tested by comparing the deflection and shrinkage of treated and untreated cantilevers heated to infiltration temperatures. The method is demonstrated with an iron nanoparticles suspension applied to parts made of 410 SS powder.

This process reduced creep by up to 95 percent and shrinkage by 50 percent. The best results were obtained using multiple applications of the nanoparticles dried under a magnetic field. Carbon deposited with the iron is shown to provide substantial benefit, but the iron is critical to establish strong bonds at low temperatures for minimal creep.

This work shows that dimensional stability of porous metal skeletons during infiltration processes can be significantly improved by treatment with nanoparticles. The increased dimensional stability afforded by this technique can combine the excellent properties of homogenous infiltration with substantially improved part accuracy and open up new applications for this manufacturing technology.

The work shows how solid freeform fabrication processes can be improved.