Part Build Orientation Optimization and Neural Network-Based Geometry Compensation for Additive Manufacturing Process

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Sushmit Chowdhury ◽  
Kunal Mhapsekar ◽  
Sam Anand
Keyword(s):  
Neural Network ◽  
Additive Manufacturing ◽  
Process Parameters ◽  
Surface Finish ◽  
Quality Measurement ◽  
Dimensional Accuracy ◽  
Build Orientation ◽  
Part Quality ◽  
Heating And Cooling ◽  
Orientation Optimization

Significant advancements in the field of additive manufacturing (AM) have increased the popularity of AM in mainstream industries. The dimensional accuracy and surface finish of parts manufactured using AM depend on the AM process and the accompanying process parameters. Part build orientation is one of the most critical process parameters, since it has a direct impact on the part quality measurement metrics such as cusp error, manufacturability concerns for geometric features such as thin regions and small fusible openings, and support structure parameters. In conjunction with the build orientation, the cyclic heating and cooling of the material involved in the AM processes lead to nonuniform deformations throughout the part. These factors cumulatively affect the design conformity, surface finish, and the postprocessing requirements of the manufactured parts. In this paper, a two-step part build orientation optimization and thermal compensation methodology is presented to minimize the geometric inaccuracies resulting in the part during the AM process. In the first step, a weighted optimization model is used to determine the optimal build orientation for a part with respect to the aforementioned part quality and manufacturability metrics. In the second step, a novel artificial neural network (ANN)-based geometric compensation methodology is used on the part in its optimal orientation to make appropriate geometric modifications to counteract the thermal effects resulting from the AM process. The effectiveness of this compensation is assessed on an example part using a new point cloud to part conformity metric and shows significant improvements in the manufactured part's geometric accuracy.

Thermal Analysis and Verification for Direct Metal Deposition of 0Cr18Ni9 Stainless Steel

2019 ◽  
Author(s):  
Jin Wang ◽  
Jing Shi ◽  
Yi Wang ◽  
Yun Bai
Keyword(s):  
Stainless Steel ◽  
Additive Manufacturing ◽  
Temperature Distribution ◽  
Process Parameters ◽  
Thermal Stresses ◽  
Infrared Camera ◽  
Dimensional Accuracy ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Heating And Cooling

Abstract Due to rapid cyclic heating and cooling in metal additive manufacturing processes, such as selective laser melting (SLM) and direct metal deposition (DMD), large thermal stresses will form and this may lead to the loss of dimensional accuracy or even cracks. The integration of numerical analysis and experimental validation provides a powerful tool that allows the prediction of defects, and optimization of the component design and the additive manufacturing process parameters. In this work, a numerical simulation on the thermal process of DMD of 0Cr18Ni9 stainless steel is conducted. The simulation is based on the finite volume method (FVM). An in-house code is developed, and it is able to calculate the temperature distribution dynamically. The model size is 30mm × 30mm × 10.5mm, containing 432,000 cells. A DMD experiment on the material with the same configuration and process parameters is also carried out, during which an infrared camera is adopted to obtain the surface temperature distribution continuously, and thermocouples are embedded in the baseplate to record the temperature histories. It is found that the numerical results agree with the experimental results well.

Additive manufacturing using fine wire-based laser metal deposition

2019 ◽  
Vol 26 (3) ◽  
pp. 473-483
Author(s):  
Muhammad Omar Shaikh ◽  
Ching-Chia Chen ◽  
Hua-Cheng Chiang ◽  
Ji-Rong Chen ◽  
Yi-Chin Chou ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Tensile Strength ◽  
Additive Manufacturing ◽  
High Precision ◽  
Surface Finish ◽  
Dimensional Accuracy ◽  
Laser Metal Deposition ◽  
Cross Sectional ◽  
Content Type ◽  
Fine Wire

Purpose Using wire as feedstock has several advantages for additive manufacturing (AM) of metal components, which include high deposition rates, efficient material use and low material costs. While the feasibility of wire-feed AM has been demonstrated, the accuracy and surface finish of the produced parts is generally lower than those obtained using powder-bed/-feed AM. The purpose of this study was to develop and investigate the feasibility of a fine wire-based laser metal deposition (FW-LMD) process for producing high-precision metal components with improved resolution, dimensional accuracy and surface finish. Design/methodology/approach The proposed FW-LMD AM process uses a fine stainless steel wire with a diameter of 100 µm as the additive material and a pulsed Nd:YAG laser as the heat source. The pulsed laser beam generates a melt pool on the substrate into which the fine wire is fed, and upon moving the X–Y stage, a single-pass weld bead is created during solidification that can be laterally and vertically stacked to create a 3D metal component. Process parameters including laser power, pulse duration and stage speed were optimized for the single-pass weld bead. The effect of lateral overlap was studied to ensure low surface roughness of the first layer onto which subsequent layers can be deposited. Multi-layer deposition was also performed and the resulting cross-sectional morphology, microhardness, phase formation, grain growth and tensile strength have been investigated. Findings An optimized lateral overlap of about 60-70% results in an average surface roughness of 8-16 µm along all printed directions of the X–Y stage. The single-layer thickness and dimensional accuracy of the proposed FW-LMD process was about 40-80 µm and ±30 µm, respectively. A dense cross-sectional morphology was observed for the multilayer stacking without any visible voids, pores or defects present between the layers. X-ray diffraction confirmed a majority austenite phase with small ferrite phase formation that occurs at the junction of the vertically stacked beads, as confirmed by the electron backscatter diffraction (EBSD) analysis. Tensile tests were performed and an ultimate tensile strength of about 700-750 MPa was observed for all samples. Furthermore, multilayer printing of different shapes with improved surface finish and thin-walled and inclined metal structures with a minimum achievable resolution of about 500 µm was presented. Originality/value To the best of the authors’ knowledge, this is the first study to report a directed energy deposition process using a fine metal wire with a diameter of 100 µm and can be a possible solution to improving surface finish and reducing the “stair-stepping” effect that is generally observed for wires with a larger diameter. The AM process proposed in this study can be an attractive alternative for 3D printing of high-precision metal components and can find application for rapid prototyping in a range of industries such as medical and automotive, among others.

Effect of process parameters on flexural strength and surface roughness in fused deposition modeling of PC-ABS material

2021 ◽  
pp. 251659842110311
Author(s):  
Shrikrishna Pawar ◽  
Dhananjay Dolas1
Keyword(s):  
Surface Roughness ◽  
Flexural Strength ◽  
Response Surface ◽  
Layer Thickness ◽  
Process Parameters ◽  
Surface Finish ◽  
Fused Deposition Modeling ◽  
Build Orientation ◽  
Fused Deposition ◽  
Deposition Modeling

Fused deposition modeling (FDM) is one of the most commonly used additive manufacturing (AM) technologies, which has found application in industries to meet the challenges of design modifications without significant cost increase and time delays. Process parameters largely affect the quality characteristics of AM parts, such as mechanical strength and surface finish. This article aims to optimize the parameters for enhancing flexural strength and surface finish of FDM parts. A total of 18 test specimens of polycarbonate (PC)-ABS (acrylonitrile–butadiene–styrene) material are printed to analyze the effect of process parameters, viz. layer thickness, build orientation, and infill density on flexural strength and surface finish. Empirical models relating process parameters with responses have been developed by using response surface regression and further analyzed by analysis of variance. Main effect plots and interaction plots are drawn to study the individual and combined effect of process parameters on output variables. Response surface methodology was employed to predict the results of flexural strength 48.2910 MPa and surface roughness 3.5826 µm with an optimal setting of parameters of 0.14-mm layer thickness and 100% infill density along with horizontal build orientation. Experimental results confirm infill density and build orientation as highly significant parameters for impacting flexural strength and surface roughness, respectively.

Thermal Modeling in Metal Additive Manufacturing Using Graph Theory

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
M. Reza Yavari ◽  
Kevin D. Cole ◽  
Prahalada Rao
Keyword(s):  
Finite Element ◽  
Graph Theory ◽  
Additive Manufacturing ◽  
Temperature Distribution ◽  
Process Parameters ◽  
Green’S Functions ◽  
Theory Approach ◽  
Finite Element Analyses ◽  
Part Quality ◽  
Am Processes

The goal of this work is to predict the effect of part geometry and process parameters on the instantaneous spatiotemporal distribution of temperature, also called the thermal field or temperature history, in metal parts as they are being built layer-by-layer using additive manufacturing (AM) processes. In pursuit of this goal, the objective of this work is to develop and verify a graph theory-based approach for predicting the temperature distribution in metal AM parts. This objective is consequential to overcome the current poor process consistency and part quality in AM. One of the main reasons for poor part quality in metal AM processes is ascribed to the nature of temperature distribution in the part. For instance, steep thermal gradients created in the part during printing leads to defects, such as warping and thermal stress-induced cracking. Existing nonproprietary approaches to predict the temperature distribution in AM parts predominantly use mesh-based finite element analyses that are computationally tortuous—the simulation of a few layers typically requires several hours, if not days. Hence, to alleviate these challenges in metal AM processes, there is a need for efficient computational models to predict the temperature distribution, and thereby guide part design and selection of process parameters instead of expensive empirical testing. Compared with finite element analyses techniques, the proposed mesh-free graph theory-based approach facilitates prediction of the temperature distribution within a few minutes on a desktop computer. To explore these assertions, we conducted the following two studies: (1) comparing the heat diffusion trends predicted using the graph theory approach with finite element analysis, and analytical heat transfer calculations based on Green’s functions for an elementary cuboid geometry which is subjected to an impulse heat input in a certain part of its volume and (2) simulating the laser powder bed fusion metal AM of three-part geometries with (a) Goldak’s moving heat source finite element method, (b) the proposed graph theory approach, and (c) further comparing the thermal trends predicted from the last two approaches with a commercial solution. From the first study, we report that the thermal trends approximated by the graph theory approach are found to be accurate within 5% of the Green’s functions-based analytical solution (in terms of the symmetric mean absolute percentage error). Results from the second study show that the thermal trends predicted for the AM parts using graph theory approach agree with finite element analyses, and the computational time for predicting the temperature distribution was significantly reduced with graph theory. For instance, for one of the AM part geometries studied, the temperature trends were predicted in less than 18 min within 10% error using the graph theory approach compared with over 180 min with finite element analyses. Although this paper is restricted to theoretical development and verification of the graph theory approach, our forthcoming research will focus on experimental validation through in-process thermal measurements.

Experimental Study on Surface Integrity, Dimensional Accuracy, and Micro-Hardness in Thin-Wall Machining of Aluminum Alloy

2018 ◽  
Vol 5 (2) ◽  
pp. 13-31
Author(s):  
Gururaj Bolar ◽  
Shrikrishna N. Joshi
Keyword(s):  
Aluminum Alloy ◽  
Process Parameters ◽  
Surface Finish ◽  
Dimensional Accuracy ◽  
Depth Of Cut ◽  
Thin Wall ◽  
Micro Hardness ◽  
Wall Deflection ◽  
High Feed ◽  
Axial Depth

This article presents an experimental investigation into the influence of process parameters viz. feed per tooth, axial depth of cut on milling force, surface finish, wall deflection and micro-hardness during thin-wall machining of an aerospace grade aluminum alloy 2024-T351. Results revealed that the process parameters significantly influence the surface finish and dimensional accuracy of machined thin-walls. High feed rate promoted the formation of built-up-edge (BUE). Combination of high feed and axial depth of cut aided in catastrophic failure of tools. Surface damages such as material plucking, material shearing, material adhesion and deformed feed mark layer formation were observed. Axial depth of cut negatively influenced the wall deflection leading to loss of dimensional accuracy. Interestingly, the micro-hardness at the machined surface was found to be lower than that of the bulk material hardness. These results will be useful in selection of suitable process parameters for quality and precise machining of thin-wall parts.

Vibration in Traverse Cut Cylindrical Grinding - Experiments and Analysis

2011 ◽  
Vol 264-265 ◽  
pp. 1124-1129 ◽  
Author(s):  
Ramesh Rudrapati ◽  
Pradip Kumar Pal ◽  
Asish Bandyopadhyay
Keyword(s):  
Process Parameters ◽  
Surface Finish ◽  
Dynamic Performance ◽  
Dimensional Accuracy ◽  
Vibration Signals ◽  
Cylindrical Grinding ◽  
Good Surface ◽  
Good Surface Finish ◽  
Grinding Machines ◽  
Grinding Machine

Good surface finish is one of the important demands from the outputs of a cylindrical grinding machine. Also it is expected that dimensional accuracy, including accuracy in roundness, is fine in traverse cut cylindrical grinding. Now, like any other machine tool, cylindrical grinding machines also do vibrate, and vibration will affect accuracy and surface finish of the parts produced in grinding. The analysis of vibration in cylindrical grinding is then very much important. In the present study some aspects of vibration – behavior of cylindrical grinding machine have been experimented and analyzed. The process parameters have been varied and vibration signals have been measured in different directions by positioning an accelerometer at tail stock of the machine. The data have been analyzed through various statistical techniques to identify and predict vibration at given combinations of process parameters. The results and analysis of data give useful idea about dynamic performance of cylindrical grinding machine in traverse cut cylindrical grinding operation.

Dimensional Accuracy in PolyJet Printing: A Literature Review

2019 ◽  
Author(s):  
Ketan Thakare ◽  
Xingjian Wei ◽  
Zhijian Pei
Keyword(s):  
Additive Manufacturing ◽  
Layer Thickness ◽  
Surface Finish ◽  
Dimensional Accuracy ◽  
High Dimensional ◽  
Control Variables ◽  
Current Trends ◽  
Manufacturing Methods ◽  
Polyjet Printing ◽  
Part Orientation

Abstract PolyJet printing process is one of the additive manufacturing methods to print parts with high dimensional accuracy. To date, dimensional accuracies of such process have been investigated by a number of studies. This review will summarize those studies, and identify current trends. With respect to methods of measurements used in the reported studies, it is noted that no special preference is given to use of any method. In addition, the effects of four control variables of PolyJet process: part orientation, layer thickness, surface finish type and materials, on dimensional accuracy are noted based on the results of reported studies. There is consistency in results in studies considering control variables of layer thickness, surface finish type and materials. However, the results are inconsistent in studies considering part orientation.

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