SLS Process Parameter Optimization to Improve Surface Quality and Accuracy of Polyamide Parts

The contribution of selective laser sintering (SLS) technique in the 4.0 manufacturing industry is undisputedly significant. SLS part quality exhibits high dependence on SLS process parameters and is a major challenge. Therefore, this research aims to investigate the effect of input parameters (i.e., part orientation, bed temperature, and layer thickness) on the surface roughness and accuracy of laser-sintered polyamide specimens. Response surface methodology (RSM) and ANOVA analysis aided the testing and evaluation. Optimal working conditions for minimum shrinkage were 0.17 mm layer thickness, 177.89°C part bed temperature, and part orientation at 88.91 degrees. The surface quality deteriorated with the increment in part bed temperature and layer thickness, and it shows an inverse trend (or improves) with the part orientation in the prescribed range. The optimal surface roughness was at a layer thickness of 0.11 mm, bed temperature at 174.55°C, and part orientation at 86.5 degrees.

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Investigation on the Surface Quality Obtained during Trochoidal Milling of 6082 Aluminum Alloy

Machines ◽

10.3390/machines9040075 ◽

2021 ◽

Vol 9 (4) ◽

pp. 75

Author(s):

Nikolaos E. Karkalos ◽

Panagiotis Karmiris-Obratański ◽

Szymon Kurpiel ◽

Krzysztof Zagórski ◽

Angelos P. Markopoulos

Keyword(s):

Surface Roughness ◽

Surface Quality ◽

Process Parameters ◽

Manufacturing Industry ◽

High Surface ◽

Cutting Tools ◽

Cutting Speed ◽

Depth Of Cut ◽

High Surface Quality ◽

Trochoidal Milling

Surface quality has always been an important goal in the manufacturing industry, as it is not only related to the achievement of appropriate geometrical tolerances but also plays an important role in the tribological behavior of the surface as well as its resistance to fatigue and corrosion. Usually, in order to achieve sufficiently high surface quality, process parameters, such as cutting speed and feed, are regulated or special types of cutting tools are used. In the present work, an alternative strategy for slot milling is adopted, namely, trochoidal milling, which employs a more complex trajectory for the cutting tool. Two series of experiments were initially conducted with traditional and trochoidal milling under various feed and cutting speed values in order to evaluate the capabilities of trochoidal milling. The findings showed a clear difference between the two milling strategies, and it was shown that the trochoidal milling strategy is able to provide superior surface quality when the appropriate process parameters are also chosen. Finally, the effect of the depth of cut, coolant and trochoidal stepover on surface roughness during trochoidal milling was also investigated, and it was found that lower depths of cut, the use of coolant and low values of trochoidal stepover can lead to a considerable decrease in surface roughness.

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A Proposed Scan Strategy Used on SLM Inner Structure Part

Materials ◽

10.3390/ma13040937 ◽

2020 ◽

Vol 13 (4) ◽

pp. 937 ◽

Cited By ~ 1

Author(s):

Jitai Han ◽

Meiping Wu ◽

Weipeng Duan

Keyword(s):

Surface Roughness ◽

Surface Quality ◽

Laser Energy ◽

Side Surface ◽

Test Results ◽

New Strategy ◽

Optimal Surface ◽

The Relationship ◽

Main Factor

A model with an inner structure was designed to study the relationship between the surface quality of the inner structure and the scan strategy in this study. The test results showed that the precision of the inner structure was highly affected by the scan strategy, and the specimens printed using different strategies showed different performances on the surface quality of the inner structure. The specimen printed using the square-framed scan strategy had a lower flatness value on the positive face of the inner structure compared to that of the other two specimens printed using Z-shape scan strategies, while the specimen printed using the Z-shape scan strategy (along the inner structure) had a relative optimal surface roughness on the side surface of the inner structure in all three specimens. The bending deformation caused by the scan strategies was considered to be the main factor affecting the flatness on the positive surface, while laser energy fluctuation showed a significant impact on side surface roughness. Combined with the experimental data, a new scan strategy was proposed; we found that the specimen printed using this new strategy improved positive surface flatness and side surface roughness.

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Influence of Process Parameters on Surface Finish in Customized Bone Implant Using Selective Laser Sintering

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.845.862 ◽

2013 ◽

Vol 845 ◽

pp. 862-867 ◽

Cited By ~ 2

Author(s):

K. Swarna Lakshmi ◽

G. Arumaikkannu

Keyword(s):

Surface Roughness ◽

Layer Thickness ◽

Surface Finish ◽

Signal To Noise Ratio ◽

Statistical Significance ◽

Selective Laser Sintering ◽

Laser Sintering ◽

Influence Of Process Parameters ◽

Bone Implant ◽

Computer Tomography Scan

Selective Laser Sintering(SLS) is a powder-based Additive Manufacturing process in which parts are built by sintering of selected areas of layers of Polyamide (PA12) powder using CO2 laser. The purpose of this work is to study experimentally the effect of orientation of the component, fill scan spacing and layer thickness on the surface roughness (Ra) of the customized bone implant fabricated through SLS technique. For this study computer tomography scan data was taken and converted to standard triangulation file (.stl) format using mimics software. Taguchis Design of Experiment approach was used for this study. An L27 Orthogonal Array (OA) of Taguchi design was used. Analysis of Variance (ANOVA) was then performed on S/N (Signal-to-Noise ratio) to determine the statistical significance and contribution of each factor on the surface roughness. The results indicated that orientation and layer thickness are significant parameters to cause appreciable improvement in surface finish.

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Surface roughness prediction of FFF-fabricated workpieces by artificial neural network and Box–Behnken method

International Journal of Metrology and Quality Engineering ◽

10.1051/ijmqe/2021014 ◽

2021 ◽

Vol 12 ◽

pp. 17

Author(s):

Karin Kandananond

Keyword(s):

Neural Network ◽

Surface Roughness ◽

Artificial Neural Network ◽

Layer Thickness ◽

Prediction Equation ◽

Cylindrical Shape ◽

Fused Deposition ◽

Bed Temperature ◽

Artificial Neural ◽

Printing Speed

Fused Filament Fabrication (FFF) or Fused Deposition Modelling (FDM) or three-dimension (3D) printing are rapid prototyping processes for workpieces. There are many factors which have a significant effect on surface quality, including bed temperature, printing speed, and layer thickness. This empirical study was conducted to determine the relationship between the above-mentioned factors and average surface roughness (Ra). Workpieces of cylindrical shape were fabricated by an FFF system with a Polylactic acid (PLA) filament. The surface roughness was measured at five different positions on the bottom and top surface. A response surface (Box-Behnken) method was utilised to design the experiment and statistically predict the response. The total number of treatments was sixteen, while five measurements (Ra1, Ra2, Ra3, Ra4 and Ra5) were carried out for each treatment. The settings of each factor were as follows: bed temperature (80, 85, and 90 °C), printing speed (40, 80 and 120 mm/s), and layer thickness (0.10, 0.25 and 0.40 mm). The prediction equation of surface roughness was then derived from the analysis. The same set of data was also used as the inputs for a machine learning method, an artificial neural network (ANN), to construct the prediction equation of surface roughness. Rectified linear unit (ReLU) was utilised as the activation function of ANN. Two training algorithms (resilient backpropagation with weight backtracking and globally convergent resilient backpropagation) were applied to train multi-layer perceptrons. Moreover, the different number of neurons in each hidden layer was also studied and compared. Another interesting aspect of this study is that the ANN was based on a limited number of training samples. Finally, the prediction errors of each method were compared, to benchmark the prediction performance of the two methods: Box-Behnken and ANN.

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Investigations on the Effect of Layers’ Thickness and Orientations in the Machining of Additively Manufactured Stainless Steel 316L

Materials ◽

10.3390/ma14071797 ◽

2021 ◽

Vol 14 (7) ◽

pp. 1797

Author(s):

Abdulmajeed Dabwan ◽

Saqib Anwar ◽

Ali M. Al-Samhan ◽

Abdullah AlFaify ◽

Mustafa M. Nasr

Keyword(s):

Surface Roughness ◽

Stainless Steel ◽

Layer Thickness ◽

Milling Process ◽

The Other ◽

Orientation Effect ◽

Micro Hardness ◽

Machined Surface ◽

Feed Force ◽

Part Orientation

Laser-powder bed fusion (L-PBF) process is a family of modern technologies, in which functional, complex (3D) parts are formed by selectively melting the metallic powders layer-by-layer based on fusion. The machining of L-PBF parts for improving their quality is a difficult task. This is because different component orientations (L-PBF-layer orientations) produce different quality of machined surface even though the same cutting parameters are applied. In this paper, stainless steel grade SS 316L parts from L-PBF were subjected to the finishing (milling) process to study the effect of part orientations. Furthermore, an attempt is made to suppress the part orientation effect by changing the layer thickness (LT) of the parts during the L-PBF process. L-PBF parts were fabricated with four different layer thicknesses of 30, 60, 80 and 100 μm to see the effect of the LT on the finish milling process. The results showed that the layer thickness of 60 μm has significantly suppressed the part orientation effect as compared to the other three-layer thicknesses of 30, 80 and 100 μm. The milling results showed that the three-layer thickness including 30, 80 and 100 μm presented up to a 34% difference in surface roughness among different part orientations while using the same milling parameters. In contrast, the layer thickness of 60 μm showed uniform surface roughness for the three-part orientations having a variation of 5–17%. Similarly, the three-layer thicknesses 30, 80 and 100 μm showed up to a 25%, 34% and 56% difference of axial force (Fa), feed force (Ff) and radial force (Fr), respectively. On the other hand, the part produced with layer thickness 60 μm showed up to 11%, 25% and 28% difference in cutting force components Fa, Ff and Fr, respectively. The three-layer thicknesses 30, 80 and 100 μm in micro-hardness were found to vary by up to 14.7% for the three-part orientation. Negligible micro-hardness differences of 1.7% were revealed by the parts with LT 60 μm across different part orientations as compared to 6.5–14% variations for the parts with layer thickness of 30, 80 and 100 μm. Moreover, the parts with LT 60 μm showed uniform and superior surface morphology and reduced edge chipping across all the part orientations. This study revealed that the effect of part orientation during milling becomes minimum and improved machined surface integrity is achieved if the L-PBF parts are fabricated with a layer thickness of 60 μm.

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The Study of Influence Laws of the Part Orientation on the Dimensions of Green Part Base on SLS

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.424-425.1233 ◽

2012 ◽

Vol 424-425 ◽

pp. 1233-1236

Author(s):

Gang Lu ◽

Qing Song Yan ◽

Xu Xiong ◽

Hong Wan ◽

Shou Yin Zhang ◽

...

Keyword(s):

Surface Quality ◽

Complex Structure ◽

Selective Laser Sintering ◽

Machining Accuracy ◽

Outstanding Problem ◽

Green Part ◽

Part Structure ◽

Structure Dimension ◽

Part Orientation ◽

Important Structure

The SLS (Selective Laser Sintering, SLS) technology can directly manufacturing any complex structure, however, due to the limitation of the manufacturing engineering factor, the surface quality and the dimension accuracy of the green part are still an outstanding problem. So, the experimental methods were adopted to study the effect of part orientation on the machining accuracy, the part orientation will significantly affects the outline of the part due to the stair-stepping phenomenon, and then affects the surface quality and the dimension accuracy. The experimental samples of different part orientations including 0, 20, 45, 60, 90 degree were fabricated, and the results indicated that the stair-stepping phenomenon significantly affected by the part orientation, when the part orientation is 0, 45 and 90 degree, the dimension accuracy is best than other part orientation, it mean the stair-stepping phenomenon is smallest. So, when the part structure is complicated, the important structure dimension should be chosen the orientation 0, 45, or 90 degree

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Pengaruh Geometri Infill terhadap Kekuatan Tarik Spesimen Uji Tarik ASTM D638 Type IV Menggunakan Filamen PLA+ Sugoi

Jurnal Rekayasa Mesin ◽

10.32497/jrm.v16i2.2343 ◽

2021 ◽

Vol 16 (2) ◽

pp. 140

Author(s):

Hasdiansah Hasdiansah ◽

Zaldy Sirwansyah Suzen

Keyword(s):

Surface Roughness ◽

3D Printing ◽

Layer Thickness ◽

Travel Speed ◽

Fused Deposition Modelling ◽

Fused Deposition ◽

Type Iv ◽

Bed Temperature ◽

Nozzle Temperature ◽

Printing Speed

Pengaturan parameter proses 3D Printing berteknologi Fused Deposition Modelling (FDM) sangat mempengaruhi kualitas produk cetak baik dalam hal akurasi dimensi, surface roughness, dan kekuatan tariknya. Dua material yang paling sering digunakan para praktisi 3D Printing adalah PLA dan ABS masih memerlukan pengaturan parameter proses pada slicing software untuk menghasilkan produk cetak paling kuat ditinjau dari kuat tariknya. Penelitian ini memvariasikan bentuk geometri infill yang tersedia pada Ultimaker Cura 4.8.0 dalam mencetak spesimen uji tarik ASTM D638 Type IV. Ada 13 (tiga belas) bentuk infill yang digunakan dengan infill density 100%. Ada 3 (tiga) variasi nozzle temperature yaitu 205°C, 215°C, dan 225°C. Parameter proses yang tetap seperti layer thickness 0,2 mm, printing speed 50 mm/s, travel speed 100 mm/s, dan bed temperature 60°C. Spesimen uji tarik dicetak masing-masing tiga buah pada 39 (tiga puluh sembilan) eksperimen dan rata-rata hasil uji tarik dihitung kemudian selanjutnya dianalisis. Nilai kekuatan tarik tertinggi diperoleh pada pengaturan nozzle temperature 205°C dengan bentuk infill concentric atau terdapat pada eksperimen nomor 9 dengan nilai 32,40 MPa. Sedangkan nilai kekuatan tarik diperoleh pada pengaturan nozzle temperature 225°C dan dengan bentuk infill cross atau pada eksperimen nomor 37 dengan nilai 19,10 MPa. Sehingga dapat disimpulkan bahwa bentuk geometri infill pada proses 3D Printing FDM sangat mempengaruhi kekuatan tarik produk cetak.

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Improving surface quality in selective laser melting based tool making

Journal of Intelligent Manufacturing ◽

10.1007/s10845-021-01744-9 ◽

2021 ◽

Author(s):

Filippo Simoni ◽

Andrea Huxol ◽

Franz-Josef Villmer

Keyword(s):

Surface Roughness ◽

Additive Manufacturing ◽

Surface Quality ◽

Selective Laser Melting ◽

Melting Process ◽

Laser Remelting ◽

Laser Melting ◽

Great Cost ◽

Starting Point ◽

Processing Techniques

AbstractIn the last years, Additive Manufacturing, thanks to its capability of continuous improvements in performance and cost-efficiency, was able to partly replace and redefine well-established manufacturing processes. This research is based on the idea to achieve great cost and operational benefits especially in the field of tool making for injection molding by combining traditional and additive manufacturing in one process chain. Special attention is given to the surface quality in terms of surface roughness and its optimization directly in the Selective Laser Melting process. This article presents the possibility for a remelting process of the SLM parts as a way to optimize the surfaces of the produced parts. The influence of laser remelting on the surface roughness of the parts is analyzed while varying machine parameters like laser power and scan settings. Laser remelting with optimized parameter settings considerably improves the surface quality of SLM parts and is a great starting point for further post-processing techniques, which require a low initial value of surface roughness.

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Influence of High-Productivity Process Parameters on the Surface Quality and Residual Stress State of AISI 316L Components Produced by Directed Energy Deposition

Journal of Materials Engineering and Performance ◽

10.1007/s11665-021-05954-3 ◽

2021 ◽

Author(s):

Gabriele Piscopo ◽

Alessandro Salmi ◽

Eleonora Atzeni

Keyword(s):

Surface Roughness ◽

Residual Stresses ◽

Surface Quality ◽

Process Parameters ◽

Energy Deposition ◽

Industrial Applications ◽

High Productivity ◽

Directed Energy Deposition ◽

Productivity Process ◽

Directed Energy

AbstractThe production of large components is one of the most powerful applications of laser powder-directed energy deposition (LP-DED) processes. High productivity could be achieved, when focusing on industrial applications, by selecting the proper process parameters. However, it is of crucial importance to understand the strategies that are necessary to increase productivity while maintaining the overall part quality and minimizing the need for post-processing. In this paper, an analysis of the dimensional deviations, surface roughness and subsurface residual stresses of samples produced by LP-DED is described as a function of the applied energy input. The aim of this work is to analyze the effects of high-productivity process parameters on the surface quality and the mechanical characteristics of the samples. The obtained results show that the analyzed process parameters affect the dimensional deviations and the residual stresses, but have a very little influence on surface roughness, which is instead dominated by the presence of unmelted particles.

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Observation in the Surface Roughness of Silicon Wafer during Semi-Fixed Abrasive Machining with Large Grains

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.69-70.253 ◽

2009 ◽

Vol 69-70 ◽

pp. 253-257

Author(s):

Ping Zhao ◽

Jia Jie Chen ◽

Fan Yang ◽

K.F. Tang ◽

Ju Long Yuan ◽

...

Keyword(s):

Surface Roughness ◽

Surface Quality ◽

Silicon Wafer ◽

Processing Parameters ◽

Wafer Surface ◽

Abrasive Machining ◽

Fixed Abrasive ◽

Is Failure ◽

Better Than

Semi-fixed abrasive is a novel abrasive. It has a ‘trap’ effect on the hard large grains that can prevent defect effectively on the surface of the workpiece which is caused by large grains. In this paper, some relevant experiments towards silicon wafers are carried out under the different processing parameters on the semi-fixed abrasive plates, and 180# SiC is used as large grains. The processed workpieces’ surface roughness Rv are measured. The experimental results show that the surface quality of wafer will be worse because of higher load and faster rotating velocity. And it can make a conclusion that the higher proportion of bond of the plate, the weaker of the ‘trap’ effect it has. Furthermore the wet environment is better than dry for the wafer surface in machining. The practice shows that the ‘trap’ effect is failure when the workpiece is machined by abrasive plate which is 4.5wt% proportion of bond in dry lapping.

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