Tolerance-Based Layer Setup Optimization for Layered Manufacturing

2010 ◽  
Author(s):  
Jack Szu-Shen Chen ◽  
Hsi-Yung Steve Feng
Keyword(s):  
Layer Thickness ◽  
Maximum Error ◽  
Layered Manufacturing ◽  
Design Model ◽  
Maximum Efficiency ◽  
Original Design ◽  
Allowable Deviation ◽  
Number Of Layers ◽  
Build Time ◽  
Model Geometry

This paper introduces a new tolerance-based method to generate the optimum layer setup required to build layered manufacturing (LM) end-user parts for maximized efficiency. To achieve this, the deviation between the final polished LM part geometry and the original design model are formulated and controlled. Maximized layer thicknesses are then realized through optimization of each layer position with respect to the design and final geometry and maximization of the allowable deviation for each layer, which consequently leads to minimization of the build time. Current LM layer setup methods do not take into account of the final part during layer setup generation, rendering layer thickness selection to operator-deemed-best. Without the ability to predict the final geometry and to optimize the layer setup accordingly, layer thickness selection is often overly conservative, causing more layers than necessary to be used. Since the LM build time increases exponentially with an increase in the number of layers, efficiency is greatly reduced with conservative layer setup. To achieve maximum efficiency, this paper proposes a new method based on error compensation and minimization to solve for the optimum layer setup necessary to allow the resulting final physical part to reliably approximate the design model geometry according to a user specified tolerance limit. Case studies have been performed in order to validate that the proposed method is able to minimize the number of layers for constructing an LM part while controlling the maximum error for tolerance conformance.

Some Geometric Techniques to Reduce Build Time in LOM

2001 ◽  
Author(s):  
Pang King Wah ◽  
Ajay Joneja
Keyword(s):  
Layered Manufacturing ◽  
Manufacturing Technology ◽  
Rectangular Grid ◽  
Geometric Properties ◽  
Traditional Technique ◽  
Laminated Object Manufacturing ◽  
Build Time ◽  
Waste Removal ◽  
Geometric Techniques

Abstract We propose a new CAPP system for the layered manufacturing technology of LOM (laminated object manufacturing). The traditional technique of building wastes much effort and time in generation of rectangular grid patterns to the exterior of the model to facilitate waste removal. In the proposed approach, several geometric properties of the model are exploited to dramatically reduce the waste removal grids. This in turn leads to reduced build-time, with no effect on the build quality. An integrated CAPP system incorporating these ideas has been developed, and an example part is presented to show how the system performs.

Multi-Direction Slicing for Layered Manufacturing

2000 ◽  
Author(s):  
Prabhjot Singh ◽  
Debasish Dutta
Keyword(s):  
Surface Quality ◽  
Layered Manufacturing ◽  
Support Structure ◽  
Surface Accuracy ◽  
Build Time ◽  
Limited Surface

Abstract Parts made by Layered Manufacturing (LM) have a limited surface accuracy and their build time is often long due to the deposition of sacrificial support structure. However, LM machines with an ability to deposit along multiple directions can improve upon the surface quality and reduce the support volume. In this paper we consider multi-directional slicing, present algorithms and implemented examples.

Design and Testing of Multistage Centrifugal Compressors With Small Diffusion Ratios

2011 ◽  
Vol 134 (4) ◽  
Author(s):  
C. Aalburg ◽  
A. Simpson ◽  
M. B. Schmitz ◽  
V. Michelassi ◽  
S. Evangelisti ◽  
...  
Keyword(s):  
Outer Radius ◽  
Maximum Efficiency ◽  
Main Stage ◽  
Outer Diameter ◽  
Large Radius ◽  
Original Design ◽  
Small Diffusion ◽  
Experimental Database ◽  
Baseline Design ◽  
Design And Optimization

Two stators of a multistage centrifugal compressor with progressively smaller outer radii have been designed, built, and tested. The aim was to achieve a significant reduction in the outer diameter of the compressor stage without compromising performance. The reduction in size was achieved by reducing the diffusion ratio (outer radius/inner radius) of the vaneless diffuser in two steps. In the first step, the outer diameter of the entire stage was reduced by 8% compared with the baseline design. In the second stage, the outer diameter was reduced by 14%. The outer radius of the smallest design was limited by the impeller exit diameter, which was kept constant, as was the axial length of the stage. The large radius baseline design has been tested on a rotating rig in a 1.5 stage setup. This setup aimed at simulating the multistage behavior by applying a pseudostage upstream of the main stage. The pseudostage consisted of a set of nonrotating preswirl vanes in order to mimic an upstream impeller and was followed by a scaled version of the return channel of the main stage. The experimental database was then used to calibrate a 1D analysis code and 3D–computational fluid dynamics methods for the ensuing design and optimization part. By applying an extensive design-of-experiments, the endwalls as well as the vanes of the stator part were optimized for maximum efficiency and operation range. In order to preserve the multistage performance, the optimization was constrained by keeping the circumferentially averaged spanwise flow profiles at the exit of the smaller radius stages within close limits to the original design. The reduced radius designs were then tested in the same 1.5 stage setup as the baseline design. The results indicate that the reduction in size was feasible without compromising the efficiency and operation range of the stage.

Offset Slices for Multidirection Layered Deposition

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Prabhjot Singh ◽  
Debasish Dutta
Keyword(s):  
Layered Manufacturing ◽  
Thin Layers ◽  
Post Processing ◽  
Build Time ◽  
Overhang Angle ◽  
Task Framework

Layered Manufacturing (LM) techniques build a part by adding thin layers of material. In this process, overhangs need to be supported by sacrificial supports, resulting in an increase in the build time, wastage of material, and costly post-processing. Metal-based LM machines with the capability to deposit material along multiple directions resolve most of the above problems. Importantly, these machines can deposit nonplanar slices. In this paper, we study such slices and present a task framework for their use with multidirectional layered deposition machines. The aim of the analysis is to identify part subvolumes that can be built using nonplanar slices for a process-dependent overhang angle. Solution methodologies for 2D, extruded parts, and general 3D parts are presented. Algorithms and illustrative example parts are included.

Calibration of the Tight Seal of the Discharge Mechanism Doors on a Rail Wagon Using Adjustable Members

2006 ◽  
Author(s):  
Jesus A. Mendoza ◽  
Luis L. Otero
Keyword(s):  
Mathematical Model ◽  
Angular Position ◽  
Maximum Error ◽  
Original Design ◽  
Influence Coefficients ◽  
Primary Element ◽  
Closed Position ◽  
Mechanical Linkage ◽  
The Mathematical Model ◽  
The Doors

Among other types of wagons, CVG Ferrominera Orinoco (FMO) uses 350 hopper type wagons for ore transportation. Each of these wagons has a mechanical linkage system, made up of nine mobile elements plus a frame to open and close two rotary doors located at the bottom of the wagons. This paper presents development of a mathematical model to find out how the calibrating lengths of the operating mechanism’s four adjustable members allow variations of the angular position of the doors from its fully closed position. The mathematical model is obtained from the total differentials of the kinematics constraints equations and is used to find the relative influence coefficients of each adjustable member on the kinematic accuracy of the doors motion. The results show that the maximum error depends mainly upon the correct positioning of the primary element. It is also proved that two of the adjustable members in the original design do not play an important role in the tight closing.

A CAD-based approach for measuring volumetric error in layered manufacturing

2016 ◽  
Vol 231 (13) ◽  
pp. 2398-2406 ◽  
Author(s):  
Biranchi Narayan Panda ◽  
Raju MVA Bahubalendruni ◽  
Bibhuti Bhusan Biswal ◽  
Marco Leite
Keyword(s):  
Rapid Prototyping ◽  
Computer Aided Design ◽  
Fused Deposition Modeling ◽  
Layered Manufacturing ◽  
Design Model ◽  
Volumetric Error ◽  
Build Orientation ◽  
Fused Deposition ◽  
Computer Aided ◽  
Aided Design

Rapid prototyping uses layered manufacturing technology to produce functional parts directly from 3D computer-aided design model without involving any tools and human intervention. Due to layer by layer deposition, volumetric error remains in the part which is basically the volumetric difference between computer-aided design model and the fabricated part. This volumetric error causes poor dimensional accuracy and surface finish, which has limited the widespread applications of rapid prototyping. Although rapid prototyping is able to produce functional parts in less build time with less material wastage, today many industries are looking for better surface quality associated with these parts. Literature discloses that the part quality can be improved by selecting proper build orientation that corresponds to minimum volumetric error. In support of this, current study presents a computer-aided design-based novel methodology to precisely measure the volumetric error in layered manufacturing process, in particular fused deposition modeling process. The proposed method accepts computer-aided design model of the part in .CAT format and automatically calculates volumetric error for different build orientations. An Excel function is integrated with it to determine optimum build orientation based on minimum volumetric error. Several simple and complex examples verified the robustness of our proposed methodology. We anticipate that the current invention will help future rapid prototyping users in producing high-quality products through an intelligent process planning.

Pre-Processing of Heterogeneous Objects for Layered Manufacturing

2001 ◽  
Author(s):  
Ki-Hoon Shin ◽  
Debasish Dutta
Keyword(s):  
Tool Path ◽  
New Technology ◽  
Three Dimensional ◽  
Layered Manufacturing ◽  
Pattern Generation ◽  
Geometric Features ◽  
Adaptive Slicing ◽  
Heterogeneous Objects ◽  
Build Time ◽  
Material Information

Abstract Layered manufacturing (LM) is emerging as a new technology that enables fabrication of three dimensional heterogeneous objects (such as Multi-materials and Functionally Gradient Materials). The steps for fabricating heterogeneous objects include model representation and material process planning. This paper introduces a method for processing the material information. It includes pre-processing (discretization), orientation (build direction selection), and adaptive slicing of heterogeneous objects. The discretization process converts all material information inside a heterogeneous object to material features like geometric features, thus it makes it possible to determine build direction by estimating build time based on geometric features and material features. It also allows adaptive slicing of heterogeneous objects to minimize surface finish and material resolution error. In addition, tool path planning can be simplified to fill pattern generation. Examples are shown.

Design and Testing of Multistage Centrifugal Compressors With Small Diffusion Ratios

2008 ◽  
Author(s):  
C. Aalburg ◽  
A. Simpson ◽  
M. B. Schmitz ◽  
V. Michelassi ◽  
S. Evangelisti ◽  
...  
Keyword(s):  
Outer Radius ◽  
Maximum Efficiency ◽  
Main Stage ◽  
Outer Diameter ◽  
Large Radius ◽  
Original Design ◽  
Small Diffusion ◽  
Experimental Database ◽  
Baseline Design ◽  
Design And Optimization

Two stators of a multistage centrifugal compressor with progressively smaller outer radii have been designed, built and tested. The aim was to achieve a significant reduction in outer diameter of the compressor stage without compromising performance. The reduction of size was achieved by reducing the diffusion ratio (outer radius/inner radius) of the vaneless diffuser in two steps. In the first step the outer diameter of the entire stage was reduced by 8% compared to the baseline design. In the second stage the outer diameter was reduced by 14%. The outer radius of the smallest design was limited by the impeller exit diameter, which was kept constant, as was the axial length of the stage. The large radius baseline design has been tested on a rotating rig in a 1.5 stage setup. This setup aimed at simulating multistage behavior by applying a pseudo stage upstream of the main stage. The pseudo stage consisted of a set of non-rotating preswirl vanes, in order to mimic an upstream impeller, and was followed by a scaled version of the return channel of the main stage. The experimental database was then used to calibrate a 1D analysis code and 3D-CFD methods for the ensuing design and optimization part. By applying extensive Design-Of-Experiments (DOE), the endwalls as well as the vanes of the stator part were optimized for maximum efficiency and operation range. In order to preserve multistage performance, the optimization was constrained by keeping the circumferentially averaged spanwise flow profiles at the exit of the smaller radius stages within close limits to the original design. The reduced radius designs were then tested in the same 1.5 stage setup as the baseline design. The results indicate that the reduction in size was feasible without compromising efficiency and operation range of the stage.

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