Cylindricity and flatness optimization for mechanical parts in additive manufacturing based on tolerance adaptive slicing

2021 ◽  
Author(s):  
Qianyong Chen ◽  
Jinghua Xu ◽  
Shuyou Zhang
Keyword(s):  
Additive Manufacturing ◽  
Adaptive Slicing ◽  
Mechanical Parts

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.

Light Weighting Solutions for Additively Manufactured Aviation Components

2019 ◽  
Author(s):  
Sandeep Medikonda ◽  
Sriraghav Sridharan ◽  
Sunil Acharya ◽  
John Doyle
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Lightweight Design ◽  
Structural Response ◽  
Primary Objective ◽  
Optimized Design ◽  
Discrete Optimization Problem ◽  
Maximum Deformation ◽  
Mechanical Parts ◽  
Manufacturing Methods

Abstract Recently, additive manufacturing methods have gained popularity for their ability to produce complex mechanical parts where conventional manufacturing methods are not suitable. Such methods not only offer a great sense of freedom to engineers but when combined with topology optimization tools can be used to simulate structures with complex shapes which satisfy the real-world loading constraints while requiring as little material as possible. Hence, combining topology optimization and additive production procedures offers a promising approach for obtaining optimized mechanical parts. This article presents a complete workflow for studying complex topology optimized parts that can be printed using additive manufacturing. We focus on topologically optimized design approach for additive manufacturing with case studies on lightweight design of aviation safety-critical parts. The complete workflow of such a setup is discussed. The Topology Optimization of these parts has been carried out using the Solid Isotropic Material with Penalization (SIMP) algorithm [1], where a discrete optimization problem is converted to a continuous problem. The primary objective of the optimization studies is to maximize the stiffness of the chosen parts while minimizing their mass at the same time. We also investigate the effect of design constraints to account for feasible manufacturing of the part while maintaining the structural response to performance loads. These optimized parts are then analyzed using a lumped layer approach to simulate powder bed fusion (PBF) [2] as a coupled thermal-structural analysis within ANSYS®, where the areas of maximum deformation and stress resulting from additive printing are predicted. The influence that the orientation of a part’s build direction has on the end results is investigated using a parametric study. Effect of a cartesian mesh vs a tetrahedron mesh on the results have been analyzed and best practices while working with coupled topology optimization and additive simulations have also been discussed.

Anisotropic Stiffness Design for Mechanical Parts Fabricated by Multi-Material Additive Manufacturing

2016 ◽  
Vol 10 (2) ◽  
pp. 231-238 ◽  
Author(s):  
Toshitake Tateno ◽  
◽  
Keyword(s):  
Additive Manufacturing ◽  
Acrylonitrile Butadiene Styrene ◽  
Material Structure ◽  
Hard Material ◽  
Single Beam ◽  
Mechanical Parts ◽  
Element Simulation ◽  
Stiffness Properties ◽  
Stiffness Design ◽  
Anisotropic Stiffness

Stiffness is an important property of mechanical structures, particularly when it is necessary for a structure to contact other structures while in motion. In this study, we employed the advantages of additive manufacturing (AM) technology to create a multi-material structure and to investigate its stiffness properties. Herein, we also present an analytical model for designing a mechanical structure consisting of two-material, single-beam units, which was verified using a finite element simulation in our study. As an example, a two-material structure with the desired stiffness was fabricated using commercially available AM technology and employing both a soft material (natural rubber) and a hard material (acrylonitrile-butadiene-styrene resin, ABS).

Combining Strings and Fibers With Additive Manufacturing Designs

2016 ◽  
Author(s):  
C. J. Kimmer ◽  
C. K. Harnett
Keyword(s):  
Tensile Strength ◽  
Additive Manufacturing ◽  
Traditional Approach ◽  
Water Soluble ◽  
Circuit Board ◽  
Process Time ◽  
Computer Assisted ◽  
Manual Labor ◽  
High Tensile Strength ◽  
Mechanical Parts

High tensile strength cables, low-resistance motor windings, and shape memory actuators are common examples of technical fibers used in robots and other electromechanical assemblies. Because properties like tensile strength, crystal structure, and polymer alignment depend strongly on processing history, these materials cannot be 3D printed with the same properties they have on the spool. Strings and fibers are inserted in mechanical parts at the end of the manufacturing process for these assemblies. When the fibers take complex paths, the installation is often done by hand. This activity can dominate the process time, increase its human labor and reduce its social sustainability [1]. This paper applies the non-traditional approach of machine embroidery to insert sheets of patterned fibers in layered additive manufacturing processes such as 3D printing and lamination. Fibers are aligned with features in laser-cut or printed parts without the manual labor of hand threading. We demonstrate that water-soluble stabilizer materials originally designed for textiles can hold hard mechanical parts in a machine embroidery hoop with enough strength and rigidity to withstand sewing through pre-existing holes in the part. Alignment to within 250 microns has been demonstrated with a sub-$300 consumer embroidery machine. Case studies in this paper include a cable-driven mechanism, a soft-to-hard electronic connection, and an electromechanical sensor. Process-compatible and commercially available materials that can be embroidered include conductive threads, shrinking threads, water-soluble threads and high tensile strength fibers. The biggest hurdle for a user interested in this automated fiber installation process is linking the existing design file with an embroidery machine file. There is a much larger user base for 2D and 3D computer-assisted design (CAD) software than for expensive and proprietary embroidery digitizing software. We take the route chosen by the laser cutter industry, where the user produces a CAD file in their preferred editor, and makes annotations that communicate where and how densely to stitch. Translation software scans the file for a particular line style and generates stitch coordinates along it. Development is done in Jupyter/iPython notebooks that allow end-users to inspect, understand, and modify the conversion code. The intent is for users of existing planar fabrication technology (whether laser, printed circuit board, or micro/nano) to apply this method to their own CAD files for a versatile and straightforward way to put advanced materials in their devices without adding manual labor. This general approach can solve a class of assembly problems relevant to underactuated tendon-driven robotics and other electromechanical systems, expanding the range of devices that can be put together using automation.

scholarly journals Surface accuracy optimization of mechanical parts with multiple circular holes for additive manufacturing based on triangular fuzzy number

2021 ◽  
Author(s):  
Jinghua Xu ◽  
Hongsheng Sheng ◽  
Shuyou Zhang ◽  
Jianrong Tan ◽  
Jinlian Deng
Keyword(s):  
Additive Manufacturing ◽  
Fuzzy Number ◽  
Typical Feature ◽  
Triangular Fuzzy Number ◽  
Optimization Approach ◽  
Tensor Voting ◽  
Mechanical Parts ◽  
Surface Accuracy ◽  
Feature Lines ◽  
Circular Holes

AbstractSurface accuracy directly affects the surface quality and performance of mechanical parts. Circular hole, especially spatial non-planar hole set is the typical feature and working surface of mechanical parts. Compared with traditional machining methods, additive manufacturing (AM) technology can decrease the surface accuracy errors of circular holes during fabrication. However, an accuracy error may still exist on the surface of circular holes fabricated by AM due to the influence of staircase effect. This study proposes a surface accuracy optimization approach for mechanical parts with multiple circular holes for AM based on triangular fuzzy number (TFN). First, the feature lines on the manifold mesh are extracted using the dihedral angle method and normal tensor voting to detect the circular holes. Second, the optimal AM part build orientation is determined using the genetic algorithm to optimize the surface accuracy of the circular holes by minimizing the weighted volumetric error of the part. Third, the corresponding weights of the circular holes are calculated with the TFN analytic hierarchy process in accordance with the surface accuracy requirements. Lastly, an improved adaptive slicing algorithm is utilized to reduce the entire build time while maintaining the forming surface accuracy of the circular holes using digital twins via virtual printing. The effectiveness of the proposed approach is experimentally validated using two mechanical models.

Development of a deposition framework for implementation of a region-based adaptive slicing strategy in arc-based metal additive manufacturing

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nitish P. Gokhale ◽  
Prateek Kala
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing Process ◽  
Complex Geometry ◽  
Dimensional Accuracy ◽  
Successful Implementation ◽  
Mathematical Function ◽  
Adaptive Slicing ◽  
Content Type ◽  
Metal Additive Manufacturing ◽  
Metal Additive

Purpose This study aims to develop and demonstrate a deposition framework for the implementation of a region-based adaptive slicing strategy for the Tungsten Inert Gas (TIG) welding-based additive manufacturing system. The present study demonstrates a deposition framework for implementing a novel region-based adaptive slicing strategy termed as Fast Interior and Accurate Exterior with Constant Layer Height (FIAECLH). Design/methodology/approach The mentioned framework has been developed by performing experiments using the design of experiments and analyzing the experimental data. Analysis results have been used to obtain the mathematical function to integrate customization in the process. The paper, in the end, demonstrates the FIAECLH framework for implementing region-based adaptive slicing strategy on the hardware level. Findings The study showcase a new way of implementing the region-based adaptive slicing strategy to arc-based metal additive manufacturing. The study articulating a new strategy for its implementation in all types of wire and arc additive manufacturing processes. Originality/value Wire-arc-based technology has the potential to deliver cost-effective solutions for metal additive manufacturing. The research on arc welding-based processes is being carried out in different dimensions. To deposit parts with complex geometry and better dimensional accuracy implementation of a novel region-based adaptive slicing strategy for the arc-based additive manufacturing process is an essential task. The successful implementation of an adaptive slicing strategy would ease the fabrication of complex geometry in less time. This paper accomplishes this need of implementing a region-based adaptive slicing strategy as no experimental investigation has been reported for the TIG-based additive manufacturing process.

Effect of Adaptive Slicing on Surface Integrity in Additive Manufacturing

2014 ◽  
Author(s):  
S. Sikder ◽  
Ahmad Barari ◽  
H. A. Kishawy
Keyword(s):  
Additive Manufacturing ◽  
Surface Integrity ◽  
Slice Thickness ◽  
Cad Model ◽  
Surface Error ◽  
Adaptive Slicing ◽  
Actual Surface ◽  
Error Factor ◽  
The Cost ◽  
Adaptive Direct Slicing

In today’s Additive Manufacturing (AM), a part is typically manufactured using layer by layer addition of material from a Computer Aided Design (CAD) model. Traditionally the CAD model is transferred to RP system after exchanging to Stereo Lithography (STL) format which is triangulated tessellation of the CAD model. Then it is sliced using different slice algorithms and machine constraints. The inherent uncertainties in this process have led to development of adaptive direct slicing technique. There are several adaptive slicing techniques but only few researches have been done to calculate an actual surface error factor and the cost aspect of the slicing algorithm. This paper proposes new adaptive algorithm to compute a surface error factor and to find the cost effective approach for slicing. The adaptive slicing algorithm dynamically calculates slice thickness and it is based on the allowable threshold for surface integrity error to optimize the cost and time. The paper also provides comparative study of previously developed adaptive models by the authors based on cusp height and surface integrity.

scholarly journals A Kind of Filling Lattice Structure Based on DFAM for Mechanical Parts: The Diamond Lattice Structure

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Xuan Yin ◽  
Wenjun Meng ◽  
Jinzhao Cheng ◽  
Hailong Wang ◽  
Xiaoxia Zhao
Keyword(s):  
Mathematical Model ◽  
Additive Manufacturing ◽  
Lattice Structure ◽  
Variable Density ◽  
Diamond Lattice ◽  
Compression Tests ◽  
Compression Performance ◽  
Mechanical Parts ◽  
Equivalent Modulus ◽  
The Mathematical Model

Thanks to the geometric and material complexity of additive manufacturing, the design space of mechanical parts has been developed, in which lattice filling structure customization can be applied to the solid filling of mechanical parts to achieve the goal of mechanical structure lightweight. A kind of diamond lattice structure unit is designed by imitating the natural method based on Design for Additive Manufacturing of mechanical parts. The mathematical model of the relative density and mechanical properties of the unit are established, and the relationship between the two is obtained, which is verified by simulations; then the relatively uniform results are obtained. The variable density hypothesis of diamond lattice structure is proposed, the methods of simulations and compression tests are used to verify the hypothesis, and the results show that the variable density structure with the density of the filling element decreasing gradually with the stress point as the center has better compression performance and concurrently verify the correctness and applicability of the equivalent modulus of elasticity mathematical model. The results of this study can be applied to the solid sandwich filling of pressure mechanical parts, and the stress density matching relationship can be carried out to further specific design.

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