scholarly journals Analysis and Optimization of Mechanical Properties of Laser-Sintered Cellulose/PLA Mixture

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 750
Author(s):  
Hui Zhang ◽  
David L. Bourell ◽  
Yanling Guo
Keyword(s):  
Mechanical Properties ◽  
Process Parameters ◽  
Laser Energy ◽  
Design Method ◽  
Laser Sintering ◽  
Post Processing ◽  
Annealing Temperatures ◽  
Scan Speed ◽  
Full Factorial

This studied aimed at improving the mechanical properties for a new biopolymer feedstock using laser-sintering technology, especially when its laser-sintered parts are intended to be applied in the industrial and medical fields. Process parameter optimization and thermal post-processing are two approaches proposed in this work to improve the mechanical properties of laser-sintered 10 wt % cellulose-polylactic acid (10%-CPLA) parts. Laser-sintering experiments using 23 full factorial design method were conducted to assess the effects of process parameters on parts’ mechanical properties. A simulation of laser-energy distribution was carried out using Matlab to evaluate the experimental results. The characterization of mechanical properties, crystallinity, microstructure, and porosity of laser-sintered 10%-CPLA parts after thermal post-processing of different annealing temperatures was performed to analyze the influence of thermal post-processing on part properties. Image analysis of fracture surfaces was used to obtain the porosity of laser-sintered 10%-CPLA parts. Results showed that the optimized process parameters for mechanical properties of laser-sintered 10%-CPLA parts were laser power 27 W, scan speed 1600 mm/s, and scan spacing 0.1 mm. Thermal post-processing at 110 °C produced best properties for laser-sintered 10%-CPLA parts.

Study on laser sintering of pine/co-PES composites and the investment casting process

2019 ◽  
Vol 25 (8) ◽  
pp. 1349-1358 ◽  
Author(s):  
Hui Zhang ◽  
David Bourell ◽  
Yanling Guo ◽  
Xiaodong Zhang ◽  
Yu Zhuang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Process Parameters ◽  
Investment Casting ◽  
Laser Sintering ◽  
Processing Temperature ◽  
Post Processing ◽  
Advanced Technique ◽  
Content Type ◽  
Structural Patterns ◽  
Complex Structural

Purpose A pine/co-PES composite (PCPES composite) was proposed as the feedstock for powder bed fusion (laser sintering, LS). This paper aims to provide some necessary experimental data and the theoretical foundation for LS of pine/co-PES, especially for the application of using the laser-sintered pine/co-PES parts as complex structural patterns in investment casting. Design/methodology/approach The PCPES composites with different pine loadings were mixed mechanically. The composite’s preheating temperature and processing temperature during LS were determined experimentally based on the material’s thermal behavior. The effects of pine powder on the binding mechanism of PCPES composites were discussed through analyzing the microstructure of the laser-sintered parts’. Mechanical properties and dimensional precision of laser-sintered PCPES parts in different pine loadings were tested, and the parts’ mechanical properties were strengthened by wax-infiltration post-processing. The influence extents of process parameters on the mechanical properties of laser-sintered 20 Wt.% pine/co-PES parts were investigated using a 1/2 fractional factorials experiment. Findings 20 Wt.% pine/co-PES is considered to be a promising wood-plastic composite for laser sintering. The relationship between mechanical strength of its laser-sintered parts and process parameters was built up using mathematical formulas. Experimental results show density, tensile strength, flexural strength and surface roughness of laser-sintered 20 Wt.% pine/co-PES parts are improved by 72.7-75.0%, 21.9-111.3%, 26.8-86.2%, 27.0-29.1% after post-process infiltration with a wax. A promising application of the wax-infiltrated laser-sintered parts is for investment casting cores and patterns. Research limitations/implications The proper process parameters and forming properties of laser-sintered parts are limited to the results of laser sintering experiments carried on using AFS 360 rapid prototyping device. Originality/value This investigation not only provides a new feedstock for laser sintering with the advantages of low cost and fabricability but also uses an advanced technique to produce personalized wood-plastic parts efficiently. Mathematical models between mechanical properties of laser-sintered PCPES parts and LS process parameters will guide the further LS experiments using the 20 Wt.% pine/co-PES composite. Besides, the laser-sintered PCPES parts after wax-infiltration post-processing are promising as complex structural patterns for use in investment casting.

scholarly journals Selective Laser Sintering of PA6: Effect of Powder Recoating on Fibre Orientation

2020 ◽  
Vol 4 (3) ◽  
pp. 108
Author(s):  
Tobias Heckner ◽  
Michael Seitz ◽  
Sven Robert Raisch ◽  
Gerrit Huelder ◽  
Peter Middendorf
Keyword(s):  
Computed Tomography ◽  
Mechanical Properties ◽  
Layer Thickness ◽  
Laser Power ◽  
Laser Energy ◽  
Fibre Orientation ◽  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Shear Stresses ◽  
Imaging Results

In Selective Laser Sintering, fibres are strongly orientated during the powder recoating process. This effect leads to an additional increase of anisotropy in the final printed parts. This study investigates the influence of process parameter variation on the mechanical properties and the fibre orientation. A full factorial design of experiment was created to evaluate the processing parameters of recoating speed, layer thickness and laser power on the part’s modulus of elasticity. Based on the mechanical testing, computed tomography was applied to selected samples to investigate the process-induced fibre microstructure, and calculate the fibre orientation tensors. The results show increasing part stiffness in the deposition direction, with decreasing layer thickness and increasing laser power, while the recoating speed only shows little effect on the mechanical performance. This complies with computed tomography imaging results, which show an increase in fibre orientation with smaller layer thickness. With thinner layers, and hence smaller shear gaps, shear stresses induced by the roller during recoating increase significantly, leading to excessive fibre reorientation and alignment. The high level of fibre alignment implies an increase of strength and stiffness in the recoating direction. In addition, thinner layer thickness under constant laser energy density results in improved melting behaviour, and thus improved fibre consolidation, consequently further increasing the mechanical properties. Meanwhile, the parameters of recoating speed and laser power do not have a significant impact on fibre orientation within their applicable process windows.

Experimental Study on Warping Height of PA12/HDPE Specimen by Selective Laser Sintering

2010 ◽  
Vol 43 ◽  
pp. 430-433
Author(s):  
Nai Fei Ren ◽  
Pan Wang ◽  
Yan Luo ◽  
Hui Juan Wu
Keyword(s):  
Process Parameters ◽  
Selective Laser Sintering ◽  
Single Layer ◽  
Dimensional Accuracy ◽  
Laser Sintering ◽  
Sintering Process ◽  
Influence Of Process Parameters ◽  
Optimum Parameters ◽  
Scan Speed ◽  
The Relationship

The dimensional accuracy and mechanics properties of parts made by Selective Laser Sintering depend greatly on the sintering process parameters. The influence of process parameters on warping weight of parts sintered by blends of polyamide (PA12) and high density polyethylene (HDPE) was studied. The relationship between the process parameters and the warping height was presented. The surface morphology of the part and uniformity of powder mixed were analyzed by SEM. The optimum parameters of minimum warping height were obtained: preheat temperature 110°C, scan speed 300mm/s, laser power 21W, thickness of single layer 0.2mm.

Preparation and Mechanical Characterization of Jute-PP and Coir-PP Bio-Composites

2015 ◽  
Vol 766-767 ◽  
pp. 122-132
Author(s):  
Tippusultan ◽  
V.N. Gaitonde
Keyword(s):  
Mechanical Properties ◽  
Research Work ◽  
Natural Fibers ◽  
Weight Ratio ◽  
Synthetic Fiber ◽  
Synthetic Fibers ◽  
Fiber Loading ◽  
High Initial Cost ◽  
Full Factorial

Polymers reinforced with synthetic fibers such as glass and carbon offer advantages of high stiffness and strength to weight ratio compared to conventional materials. Despite these advantages, the prevalent use of synthetic fiber-reinforced polymer composite has a tendency to demur because of high initial cost and most importantly their adverse environmental impact. On the contrary, the increased interest in using natural fibers as reinforcement in plastics to substitute conventional synthetic fibers in automobile applications has become one of the main concerns to study the potential of using natural fibers as reinforcement for polymers. In this regard, an investigative study has been carried out to make potential utilization of natural fibers such as Jute and Coir as reinforcements, which are cheap and abundantly available in India. The objective of the present research work is to study the effects of fiber loading and particle size; fiber loading and fiber length on the mechanical properties of Jute-PP and Coir-PP bio-composites respectively. The experiments were planned as per full factorial design (FFD) and response surface methodology (RSM) based second order mathematical models of mechanical properties have been developed. Analysis of variance (ANOVA) has been employed to check the adequacy of the developed models. From the parametric analysis, it is revealed that Jute-PP bio-composites exhibit better mechanical properties when compared to Coir-PP bio-composites.

scholarly journals Preliminary Testing to Determine the Best Process Parameters for Polymer Laser Sintering of a New Polypropylene Polymeric Material

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Fredrick M. Mwania ◽  
Maina Maringa ◽  
Jakobus. G. van der Walt
Keyword(s):  
Mechanical Properties ◽  
Polymeric Material ◽  
Process Parameters ◽  
Laser Power ◽  
Scanning Speed ◽  
Laser Sintering ◽  
Process Conditions ◽  
Preliminary Testing ◽  
Chamber Temperature ◽  
Suitable Process

Polymer laser sintering is an elaborate additive manufacturing technique because it is subject to process parameters and material properties. In this regard, each polymeric material necessitates a different set of process conditions. To this end, testing was done to determine the most suitable process parameters for a new commercially available polymer (Laser PP CP 60), from Diamond Plastics GmbH. It was established that the material requires slightly different settings from those provided by the supplier for the values for the removal chamber temperature, building chamber temperatures, and laser power to achieve the best mechanical properties (ultimate tensile strength). The preliminary testing indicates that the process parameters that yielded the best mechanical properties for the laser PP CP 60 powder were 125°C, 125°C, 0.15 mm, 250 μm, 4500 mm/s, 34.7 W, 1500 mm/s, and 21.3 W for the removal chamber temperature, building chamber temperature layer thickness, hatch distance, scanning speed fill, laser power fill, scanning speed contour, and laser power contour, respectively.

scholarly journals Manufacturing of Porous Polycaprolactone Prepared with Different Particle Sizes and Infrared Laser Sintering Conditions: Microstructure and Mechanical Properties

2014 ◽  
Vol 6 ◽  
pp. 640496 ◽  
Author(s):  
G. V. Salmoria ◽  
D. Hotza ◽  
P. Klauss ◽  
L. A. Kanis ◽  
C. R. M. Roesler
Keyword(s):  
Mechanical Properties ◽  
Energy Density ◽  
Laser Energy ◽  
Flexural Modulus ◽  
Selective Laser Sintering ◽  
Polymeric Materials ◽  
Laser Sintering ◽  
Laser Energy Density ◽  
Particle Sizes ◽  
Mechanical Devices

The techniques of Rapid Prototyping, also known as Additive Manufacturing, have prompted research into methods of manufacturing polymeric materials with controlled porosity. This paper presents the characterization of the structure and mechanical properties of porous polycaprolactone (PCL) fabricated by Selective Laser Sintering (SLS) using two different particle sizes and laser processing conditions. The results of this study indicated that it is possible to control the microstructure, that is, pore size and degree of porosity, of the polycaprolactone matrix using the SLS technique, by varying the particle size and laser energy density, obtaining materials suitable for different applications, scaffolds and drug delivery and fluid mechanical devices. The specimens manufactured with smaller particles and higher laser energy density showed a higher degree of sintering, flexural modulus, and fatigue resistance when compared with the other specimens.

Characterization and optimization of laser sintering copolyamide/polyether sulfone hot-melt adhesive mixtures

2019 ◽  
Vol 25 (3) ◽  
pp. 614-622
Author(s):  
Hui Zhang ◽  
Yanling Guo ◽  
Kaiyi Jiang ◽  
David Bourell ◽  
Jian Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Laser Energy ◽  
Laser Sintering ◽  
Polymer Mixture ◽  
Binding Mechanism ◽  
Content Type ◽  
Polyether Sulfone ◽  
Cent Increase ◽  
Mass Ratios ◽  
Hot Melt

PurposeA new kind of polymer mixture (co-PA-PES) was prepared in different mass ratios, by mixing polyether sulfone hot-melt adhesive (PES-HmA) and copolyamide B249 (PA-B249). This study aims to investigate its characteristics of laser sintering and get the optimal process parameters.Design/methodology/approachThe effect of mass ratio of co-PA-PES on thermal behavior was analyzed using a simultaneous thermal analyzer, and the density and mechanical properties of sintered parts were tested to evaluate the performance of the polymeric system. Scanning electron microscopy and Fourier transform infrared spectroscopy were performed to characterize the microstructure and binding mechanism of sintered co-PA-PES parts. Specifically, mechanical properties of the mixture with 20 Wt.% PA-B249 were optimized based on a design of experiment methodology, along with the restriction of maximum absorbable laser energy density.FindingsLiquid phase fusion was considered as the main sintering mechanism for co-PA-PES, and mechanical interlocking was the dominant binding mechanism. The effects of mass ratios of this material on the thermal properties, density and mechanical properties were obtained via data results. Additionally, compared to neat PES-HmA, co-20 Wt.% PA-PES showed a 71.7 per cent increase in tensile strength, 24.4 per cent increase in flexural strength and 102.1per cent increase in impact strength.Originality/valueThis paper proposed a new kind of polymer mixture as the feedstock for laser sintering with the advantages of low price and easy processing. The filler of PA-B249 effectively improved the performance of the polymer mixture, including but not limited to mechanical properties.

Optimization of parameters for SLS of WC-Co

2017 ◽  
Vol 23 (6) ◽  
pp. 1202-1211 ◽  
Author(s):  
Sanjay Kumar ◽  
Aleksander Czekanski
Keyword(s):  
Energy Density ◽  
Process Parameters ◽  
Laser Power ◽  
Laser Energy ◽  
Beam Diameter ◽  
Content Type ◽  
Powder Bed ◽  
Scan Speed ◽  
New Equation ◽  
Hatch Spacing

Purpose WC-Co is a well-known material for conventional tooling but is not yet commercially available for additive manufacturing. Processing it by selective laser sintering (SLS) will pave the way for its commercialization and adoption. Design/methodology/approach It is intended to optimize process parameters (laser power, hatch spacing, scan speed) by fabricating a bigger part (minimum size of 10 mm diameter and 5 mm height). Microstructural analysis, EDX and hardness testing is used to study effects of process parameters. Optimized parameter is ascertained after fabricating 49 samples in preliminary experiment, 27 samples in pre-final experiment and 9 samples in final experiment. Findings Higher laser power gives rise to cracks and depletion of cobalt while higher scan speed increases porosity. Higher hatch spacing is responsible for delamination and displacement of parts. Optimized parameters are 270 W laser power, 500 mm/s scan speed, 0.04 mm layer thickness, 0.04 mm hatch spacing (resulting in energy density of 216 J/mm3) and 200°C powder bed temperature. A part comprising of small hole of 2 mm diameter, thin cylindrical pin of 0.5 mm diameter and thin wall of 2 mm width bent up to 30° angle to the base plate is fabricated. In order to calculate laser energy density, a new equation is introduced which takes into account both beam diameter and hatch spacing unlike old equation does. In order to calculate laser energy density, a new equation is formulated which takes into account both beam diameter and hatch spacing unlike old equation does. WC was not completely melted as intended giving rise to partial melting-type binding mechanism. This justified the name SLS for process in place of SLM (Selective Laser Melting). Research limitations/implications Using all possible combination of parameters plus heating the part bed to maximum shows limitation of state-of-the-art commercial powder bed fusion machine for shaping hardmetal consisting of high amount of WC (83 wt. per cent). Practical implications The research shows that microfeatures could be fabricated using WC-Co which will herald renewed interest in investigating hardmetals using SLS for manufacturing complex hard tools, molds and wear-resistance parts. Originality/value This is the first time micro features are successfully fabricated using WC-Co without post-processing (infiltration, machining) and without the help of additional binding material (such as Cu, Ni, Fe).

scholarly journals Improvement on Selective Laser Sintering and Post-Processing of Polystyrene

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 956 ◽  
Author(s):  
Zhi Zeng ◽  
Xiaohu Deng ◽  
Jiangmei Cui ◽  
Hai Jiang ◽  
Shuo Yan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Orthogonal Experiment ◽  
Selective Laser Sintering ◽  
Single Layer ◽  
Dimensional Accuracy ◽  
Amorphous Polymers ◽  
Laser Sintering ◽  
Temperature Fields ◽  
Post Processing ◽  
Forming Process

Amorphous polymers are heavily utilized materials in selective laser sintering (SLS) due to their good dimensional accuracy. However, sintered parts of amorphous polymers cannot be used as functional parts owing to their poor forming performance, including their low relative densities and tensile strength. Therefore, post-processing methods are employed to enhance the mechanical properties of amorphous polymers SLS parts without damaging their relatively high dimensional accuracy. In this study, the forming process of selective laser sintering (SLS) and post-processing on polystyrene (PS) was investigated. The orthogonal experiment was designed to obtain the optimal combination of process parameters. The effect of a single process parameter and the laser volumetric energy density (LVED) on dimension accuracy and warpage of the sintered parts were also discussed. In addition, a three-dimensional (3D) thermal model was developed to analyze the temperature fields of single-layer SLS parts and PS powder sintering mechanism. Then, infiltrating with epoxy resin was employed to enhance the mechanical properties of the PS parts. Good resin-infiltrated formulation was obtained based on the mechanical property tests and fractured surface analysis. This research provides guidance for SLS process and post-processing technology in polymers.

The Optimization Design Study of Selective Laser Sintering Process Parameters on the Pro-Coated Sand Mold

2011 ◽  
Vol 55-57 ◽  
pp. 853-858
Author(s):  
Rong Cheng ◽  
Xiao Yu Wu ◽  
Jian Ping Zheng
Keyword(s):  
Layer Thickness ◽  
Process Parameters ◽  
Laser Power ◽  
Selective Laser Sintering ◽  
Dimensional Accuracy ◽  
Processing Parameters ◽  
Laser Sintering ◽  
Process Variables ◽  
Scan Speed ◽  
Coated Sand

This paper presents experimental investigations on influence of important process parameters viz., laser power, scan speed, layer thickness, hatching space along with their interactions on dimensional accuracy of Selective Laser Sintering (SLS) processed pro-coated sand mold. It is observed that dimensional error is dominant along length and width direction of built mold. Optimum parameters setting to minimize percentage change in length and width of standard test specimen have been found out using Taguchi’s parameter design. Optimum process conditions are obtained by analysis of variance (ANOVA) is used to understand the significance of process variables affecting dimension accuracy. Scan speed and hatching space are found to be most significant process variables influencing the dimension accuracy in length and width. And laser power and layer thickness are less influence on the dimension accuracy. The optimum processing parameters are attained in this paper: laser power 11 W; scan speed 1200 mm/s; layer thickness 0.5 mm and hatching space 0.25 mm. It has been shown that, on average, the dimensional accuracy under this processing parameters combination could be improved by approximately up to 25% compared to other processing parameters combinations.

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