scholarly journals Search for the Optimal Build Direction in Additive Manufacturing Technologies: A Review

2020 ◽  
Vol 4 (3) ◽  
pp. 71 ◽  
Author(s):  
Luca Di Angelo ◽  
Paolo Di Stefano ◽  
Emanuele Guardiani
Keyword(s):  
Additive Manufacturing ◽  
Optimization Techniques ◽  
Manufacturing Cost ◽  
Layer By Layer ◽  
Part Quality ◽  
Advantages And Disadvantages ◽  
Build Time ◽  
Set Up ◽  
Manufacturing Technologies ◽  
The Cost

By additive manufacturing technologies, an object is produced deposing material layer by layer. The piece grows along the build direction, which is one of the main manufacturing parameters of Additive Manufacturing (AM) technologies to be set-up. This process parameter affects the cost, quality, and other important properties of the manufactured object. In this paper, the Objective Functions (OFs), presented in the literature for the search of the optimal build direction, are considered and reviewed. The following OFs are discussed: part quality, surface quality, support structure, build time, manufacturing cost, and mechanical properties. All of them are distinguished factors that are affected by build direction. In the first part of the paper, a collection of the most significant published methods for the estimation of the factors that most influence the build direction is presented. In the second part, a summary of the optimization techniques adopted from the reviewed papers is presented. Finally, the advantages and disadvantages are briefly discussed and some possible new fields of exploration are proposed.

scholarly journals Adaptive Slicing in Additive Manufacturing Process Using a Modified Boundary Octree Data Structure

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Nandkumar Siraskar ◽  
Ratnadeep Paul ◽  
Sam Anand
Keyword(s):  
Data Structure ◽  
Additive Manufacturing ◽  
Layer By Layer ◽  
Adaptive Slicing ◽  
Stl File ◽  
Part Quality ◽  
Part Geometry ◽  
Build Time ◽  
Part Surface ◽  
Am Processes

In additive manufacturing (AM) processes, the layer-by-layer fabrication leads to a staircase error resulting in dimensional inaccuracies in the part surface. Using thinner slices reduces the staircase error and improves part accuracy but also increases the number of layers and the build time for manufacturing the part. Another approach called adaptive slicing uses slices of varying thicknesses based on the part geometry to build the part. A new algorithm to compute adaptive slice thicknesses using octree data structure is presented in this study. This method, termed as modified boundary octree data structure (MBODS) algorithm, is used to convert the stereolithography (STL) file of an object to an octree data structure based on the part's geometry, the machine parameters, and a user defined tolerance value. A subsequent algorithm computes the variable slice thicknesses using the MBODS representation of the part and virtually manufactures the part using these calculated slice thicknesses. Points sampled from the virtually manufactured part are inspected to evaluate the volumetric, profile, and cylindricity part errors. The MBODS based slicing algorithm is validated by comparing it with the uniform slicing approach using various slice thicknesses for different parts. The developed MBODS algorithm is observed to be more effective in improving the part quality while using lesser number of slices.

scholarly journals A STRUCTURED APPROACH TO REDUCE DESIGN ITERATIONS IN ADDITIVE MANUFACTURING

2021 ◽  
Vol 1 ◽  
pp. 231-240
Author(s):  
Laura Wirths ◽  
Matthias Bleckmann ◽  
Kristin Paetzold
Keyword(s):  
Additive Manufacturing ◽  
Spare Parts ◽  
Design Guidelines ◽  
Final Part ◽  
Layer By Layer ◽  
Powder Bed ◽  
Batch Sizes ◽  
Manufacturing Technologies ◽  
Structured Approach ◽  
Design Freedom

AbstractAdditive Manufacturing technologies are based on a layer-by-layer build-up. This offers the possibility to design complex geometries or to integrate functionalities in the part. Nevertheless, limitations given by the manufacturing process apply to the geometric design freedom. These limitations are often unknown due to a lack of knowledge of the cause-effect relationships of the process. Currently, this leads to many iterations until the final part fulfils its functionality. Particularly for small batch sizes, producing the part at the first attempt is very important. In this study, a structured approach to reduce the design iterations is presented. Therefore, the cause-effect relationships are systematically established and analysed in detail. Based on this knowledge, design guidelines can be derived. These guidelines consider process limitations and help to reduce the iterations for the final part production. In order to illustrate the approach, the spare parts production via laser powder bed fusion is used as an example.

scholarly journals Influence of Deposition Patterns on Distortion of H13 Steel by Wire-Arc Additive Manufacturing

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 485
Author(s):  
Xufeng Li ◽  
Jian Lin ◽  
Zhidong Xia ◽  
Yongqiang Zhang ◽  
Hanguang Fu
Keyword(s):  
Additive Manufacturing ◽  
Temperature History ◽  
H13 Steel ◽  
Deposition Patterns ◽  
Field Distortion ◽  
Set Up ◽  
Manufacturing Technologies ◽  
Inherent Strain ◽  
Inherent Strain Method ◽  
Wire Arc Additive Manufacturing

Wire-arc additive manufacturing (WAAM) has been considered as one of the potential additive-manufacturing technologies to fabricate large components. However, its industrial application is still limited by the existence of stress and distortion. During the process of WAAM, the scanning pattern has an important influence on the temperature field, distortion and final quality of the part. Four kinds of deposition patterns, including sequence, symmetry, in–out and out–in, were designed to deposit H13 steel in this study. An in situ measurement system was set up to record the temperature history and the progress of accumulated distortion of the parts during deposition. An S value was proposed to evaluate the distortion of the substrate. It was shown that the distortion of the part deposited by sequence was significantly larger than those of other parts. The distortion deposited by the out–in pattern decreased by 68.6% compared with sequence. The inherent strain method and strain parameter were introduced to expose the mechanism of distortion reduction caused by pattern variation.

scholarly journals Effects of Positioning Conditions on Material Properties In Powder bed Fusion Additive Manufacturing

2021 ◽  
Author(s):  
Mevlüt Yunus Kayacan ◽  
Nihat Yılmaz
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Layer By Layer ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Cooling Rates ◽  
Powder Bed ◽  
Manufacturing Technologies ◽  
Average Size ◽  
Hardness Values

Abstract Among additive manufacturing technologies, Laser Powder Bed Fusion (L-PBF) is considered the most widespread layer-by-layer process. Although the L-PBF, which is also called as SLM method, has many advantages, several challenging problems must be overcome, including part positioning issues. In this study, the effect of part positioning on the microstructure of the part in the L-PBF method was investigated. Five Ti6Al4V samples were printed in different positions on the building platform and investigated with the aid of temperature, porosity, microstructure and hardness evaluations. In this study, martensitic needles were detected within the microstructure of Ti6Al4V samples. Furthermore, some twins were noticed on primary martensitic lines and the agglomeration of β precipitates was observed in vanadium rich areas. The positioning conditions of samples were revealed to have a strong effect on temperature gradients and on the average size of martensitic lines. Besides, different hardness values were attained depending on sample positioning conditions. As a major result, cooling rates were found related to positions of samples and the location of point on the samples. Higher cooling rates and repetitive cooling cycles resulted in microstructures becoming finer and harder.

scholarly journals Precision and Energy Usage for Additive Manufacturing

2013 ◽  
Author(s):  
Lee Clemon ◽  
Anton Sudradjat ◽  
Maribel Jaquez ◽  
Aditya Krishna ◽  
Marwan Rammah ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Energy Demand ◽  
Fused Deposition Modeling ◽  
Distinct Pattern ◽  
Energy Usage ◽  
Warm Up ◽  
Part Quality ◽  
Fused Deposition ◽  
Manufacturing Technologies ◽  
Control Part

Market pressures on manufacturing enterprises incentivize minimum resource consumption while maintaining part quality. Facilities with advanced manufacturing tools often utilize rapid prototyping for production of complicated or specialty parts. Additive manufacturing offers an alternative to traditional production methods which are often time and resource expensive. This study aims to explore part quality and energy usage for additive manufacturing through a focused study of Fused Deposition Modeling and Photopolymer Jetting technologies. A control part is developed for maintaining test consistency across different machines. The control part design consists of various positive and negative features including width varied slots and walls, ramps, and curved features so that the manufacturing of different surfaces may be investigated. Several different machine models are tested to evaluate precision for a variety of applications. Part quality is quantified by measuring the surface roughness in two directions for the control test part printed on each machine. Qualitatively, part quality is assessed by positive and negative feature resolution. High quality machines resolve features closely to design specifications. Lower quality machines do not resolve some features. In addition to exploring the effects of advertised print precision, layup density is varied on two machines. Advertised print resolution does not well represent the achievable feature sizes found in this study. Energy usage is quantified by measuring electricity demands while printing the control part on each of the five different machines. Power consumption in additive manufacturing is found to follow a distinct pattern comprised of standby, warm up, printing and idle phases. Measurement and analysis suggest a relationship between the precision of these machines and their respective energy demand. Part quality is found to generally improve with increased initial and process resource investment. The energy and quality assessment methods developed in this study are applicable to a greater variety of additive manufacturing technologies and will assist designers as additive manufacturing becomes more production friendly. The presented data also provides designers and production planners insight for improvements in the process decision making.

Increasing Part Accuracy in Additive Manufacturing Processes Using a k-d Tree Based Clustered Adaptive Layering

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Neeraj Panhalkar ◽  
Ratnadeep Paul ◽  
Sam Anand
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Layer By Layer ◽  
Adaptive Slicing ◽  
Stl File ◽  
Build Time ◽  
Standard File Format ◽  
Aided Design ◽  
Profile Errors

Additive manufacturing (AM) is widely used in aerospace, automobile, and medical industries for building highly accurate parts using a layer by layer approach. The stereolithography (STL) file is the standard file format used in AM machines and approximates the three-dimensional (3D) model of parts using planar triangles. However, as the STL file is an approximation of the actual computer aided design (CAD) surface, the geometric errors in the final manufactured parts are pronounced, particularly in those parts with highly curved surfaces. If the part is built with the minimum uniform layer thickness allowed by the AM machine, the manufactured part will typically have the best quality, but this will also result in a considerable increase in build time. Therefore, as a compromise, the part can be built with variable layer thicknesses, i.e., using an adaptive layering technique, which will reduce the part build time while still reducing the part errors and satisfying the geometric tolerance callouts on the part. This paper describes a new approach of determining the variable slices using a 3D k-d tree method. The paper validates the proposed k-d tree based adaptive layering approach for three test parts and documents the results by comparing the volumetric, cylindricity, sphericity, and profile errors obtained from this approach with those obtained using a uniform slicing method. Since current AM machines are incapable of handling adaptive slicing approach directly, a “pseudo” grouped adaptive layering approach is also proposed here. This “clustered slicing” technique will enable the fabrication of a part in bands of varying slice thicknesses with each band having clusters of uniform slice thicknesses. The proposed k-d tree based adaptive slicing approach along with clustered slicing has been validated with simulations of the test parts of different shapes.

Optimization of the Dynamic Response of Semi-Submersibles: Influence of the Mooring System

2019 ◽  
Author(s):  
Shengtao Zhou ◽  
Frank Lemmer ◽  
Wei Yu ◽  
Po Wen Cheng ◽  
Chao Li ◽  
...  
Keyword(s):  
Life Cycle Cost ◽  
Design Space ◽  
Optimization Techniques ◽  
Optimization Process ◽  
Manufacturing Cost ◽  
Mooring System ◽  
Mooring Lines ◽  
Nsga Ii ◽  
Simulation Code ◽  
Set Up

Abstract The design and manufacturing cost of substructures is a major component of the total expenditure for a floating wind project. Applying optimization techniques to hull shape designs has become an effective way to reduce the life-cycle cost of a floating wind system. The mooring system is regarded as the component with the highest risk, mainly due to the poor accessibility. This paper extends the previous work by investigating the influences of the mooring design on the optimization process of a semisubmersible substructure. Two optimization loops are set up. In the first loop, only the main dimensions of a semi-submersible platform are parameterized without considering mooring lines (keep a constant mooring design). Nevertheless, the second loop introduces additional variables of the mooring lines. The objective is to minimize the tower-top displacement, fairlead fatigue damage, which are calculated by the in-house nonlinear dynamic simulation code SLOW, and the manufacturing cost of platform and mooring lines. The multi-objective optimization algorithm NSGA-II is employed to search for the optimal designs within the defined design space. The design space and the Pareto fronts are compared between the two optimizations. It is found that, although the mooring design does not have a significant impact on the platform design space, one obtains a different optimal set (Pareto front) if the mooring design and mooring loads are introduced into the platform optimization process. The results of this study are expected to give a better understanding in the relationship between platform and mooring design and serve as a basis for the optimization process of semi-submersible floating wind turbines.

Build Direction for Improved Process Plan in Multi-Material Additive Manufacturing

2014 ◽  
Author(s):  
Bashir Khoda
Keyword(s):  
Additive Manufacturing ◽  
Material Object ◽  
Layer By Layer ◽  
Multiple Features ◽  
Process Plan ◽  
Material Deposition ◽  
Heterogeneous Object ◽  
Build Time ◽  
Material Process ◽  
Manufacturing Techniques

Current additive manufacturing processes mostly accustomed with mono-material process plan algorithm to build object layer by layer. However, building a multi-material or heterogeneous object with an additive manufacturing system is fairly new but emerging concept. Unlike mono-material object, heterogeneous object contains multiple features or inhomogeneous architecture and can be decomposed into two dimensional heterogeneous layers with islands where each island represents associated feature’s properties. The material deposition path-plan in such multi-feature/multi-contour layers requires more resources and may affect the part integrity, quality, and build time. A novel framework is presented in this paper to determine the optimum build direction for heterogeneous object by differentiating the slice based on the resources requirement. Slices are bundled based on the heterogeneity and the effect of build directions are quantified considering the feature characteristics and manufacturing attributes. The proposed methodology is illustrated by examples with 50% or more homogeneous slices along the optimum build direction. The outcome would certainly benefit the process plan for multi-material additive manufacturing techniques.

scholarly journals Analysis and characterization of additive manufacturing processes

2021 ◽  
Vol 13 (4) ◽  
pp. 167-180
Author(s):  
Andra TOFAN-NEGRU ◽  
Cristian BARBU ◽  
Amado STEFAN ◽  
Ioana-Carmen BOGLIS
Keyword(s):  
Additive Manufacturing ◽  
Complex Geometry ◽  
Cutting Tools ◽  
Manufacturing Processes ◽  
Layer By Layer ◽  
Advantages And Disadvantages ◽  
Finishing Processes ◽  
Short Time ◽  
Physical Phenomena ◽  
Am Processes

Recently, additive manufacturing (AM) processes have expanded rapidly in various fields of the industry because they offer design freedom, involve layer-by-layer construction from a computerized 3D model (minimizing material consumption), and allow the manufacture of parts with complex geometry (thus offering the possibility of producing custom parts). Also, they provide the advantage of a short time to make the final parts, do not involve the need for auxiliary resources (cutting tools, lighting fixtures or coolants) and have a low impact on the environment. However, the aspects that make these technologies not yet widely used in industry are poor surface quality of parts, uncertainty about the mechanical properties of products and low productivity. Research on the physical phenomena associated with additive manufacturing processes is necessary for proper control of the phenomena of melting, solidification, vaporization and heat transfer. This paper addresses the relevant additive manufacturing processes and their applications and analyzes the advantages and disadvantages of AM processes compared to conventional production processes. For the aerospace industry, these technologies offer possibilities for manufacturing lighter structures to reduce weight, but improvements in precision must be sought to eliminate the need for finishing processes.

scholarly journals A 3D weaving infill pattern for fused filament fabrication

2021 ◽  
Author(s):  
Yuan Yao ◽  
Cheng Ding ◽  
Mohamed Aburaia ◽  
Maximilian Lackner ◽  
Lanlan He
Keyword(s):  
Additive Manufacturing ◽  
Three Dimensional ◽  
Layer By Layer ◽  
Fused Filament Fabrication ◽  
Repetitive Structure ◽  
Mechanical Linkage ◽  
Manufacturing Technologies ◽  
Dimensional Object ◽  
Anisotropy Of Mechanical Properties ◽  
3D Weaving

Abstract The Fused Filament Fabrication process is the most used additive manufacturing process due to its simplicity and low operating costs. In this process, a thermoplastic filament is led through an extruder, melted, and applied to a building platform by the axial movements of an automated Cartesian system in such a way that a three-dimensional object is created layer by layer. Compared to other additive manufacturing technologies, the components produced have mechanical limitations and are often not suitable for functional applications. To reduce the anisotropy of mechanical strength in fused filament fabrication (FFF), this paper proposes a 3D weaving deposit path planning method that utilizes a 5-layer repetitive structure to achieve interlocking and embedding between neighbor slicing planes to improve the mechanical linkage within the layers. The developed algorithm extends the weaving path as an infill pattern to fill different structures and makes this process feasible on a standard three-axis 3D printer. Compared with 3D weaving printed parts by layer-to-layer deposit, the anisotropy of mechanical properties inside layers is significantly reduced to 10.21% and 0.98%.

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