Rapid Qualification Methods for Powder Bed Direct Metal AM Processes:

This project, funded by National Additvie Manufacturing Innovation InstitiuteMELT POOL (NAMII) and The National Science Foundation (NSF) directly targets the missing links between the ability to build freeform shapes and controlling microstructure and properties across both the EOS and Arcam processes. These links are key to qualifying both processes for use in fabricating components for the aerospace and other industries. This goal is made possible by taking a unique modeling-based process mapping approach to understanding process variable vs. melt pool geometry and microstructure process characteristics and linking that approach to advanced microstructural modeling. Its ultimate outcome will be verified methods for performing small numbers of tests to fully map out melt pool geometry, microstructure and properties across processing space.

Rapid Machining of Additively Produced Metal Parts:

A key problem with components fabricated with direct metal additive manufacturing methods is that the parts are near net shape. These parts must be finish machined and, this presents unique challenges especially for small batch sizes of custom parts.  This project, funded by the National Science Foundation, enables us to gain engineering design and manufacturing experience for the process by developing algorithms for placing sacrificial fixtures on a variety of parts. Successful implementation will drastically reduce production time and manual finishing processes will be eliminated/minimized. The intent is to develop formal algorithms that can add sacrificial fixtures to a complex design; produce the part using EBM (additive manufacturing) and then finish-machining precision geometric surfaces using CNC-RP technique.  

3-D sensing for localization and error compensation in Hybrid Additive/Subtractive Manufacturing

The aim of this research is to develop and verify a set of systems that will captureScanning surface data from a workpiece placed in a CNC-machining station and use this captured data to compensate for any differences in position, orientation and form between the expected (nominal) workpiece and the workpiece actually present in the system before and during the machining process.

The systems, modules and algorithms developed will be studied, optimized, and integrated into the AIMS hybrid manufacturing process, currently under development. This integration will help allow for the rapid production of parts with complex geometries while greatly reducing the

need for skilled labor, expensive tooling and the associated lead times, and while enabling more efficient use of expensive materials that would otherwise be subject to excessive loss (waste and scrap) during manufacture.

Fiber Reinforced Polymers with Tailored Properties via Additive Manufacturing

The purpose of the proposed research is to investigate the material properties achieved through an additive manufacturing process for fiber reinforced composites. The additive manufacturing process is under development and a number of material combinations have been investigated and evaluated. The in-compositehouse system is based on DLP (Digital Light Processing™) technology, where visible or ultraviolet light curable resins can be cured in layers by the projection of a layer image and continuous or discontinuous fibers can be deposited in random or structured orientation between or within these layers. The system under development will allow for a wide range of material properties and the construct can be tailored to the application. Besides different resin and fiber combinations the fiber load and fiber orientation can be controlled for each layer to achieve the required mechanical properties of the component.  This project builds off of a previous research project, in which a a software system was developed to determine the preferential fiber alignment in a composite component based on the stresses resulting from the predicted loading regimes.

Modeling of 3D Auxectic Structures Produced Via Additive Manufacturing.

IMG_0286In this work, a 2D re-entrant honeycomb structure was adapted into a 3D auxetic structure, and modeled via both the Timoshenko beam theory and the Euler-Bernoulli beam theory. Design parameter driven models were derived that could predict various mechanical properties of this auxetic structure such as strength, elastic modulus and Poisson’s ratio. The models were verified with a combined approach of finite element analysis (FEA) and physical experiments, taking advantage of additive manufacturing processes such as electron beam melting (EBM), Objet3D printing, and selective laser sintering (SLS). Results showed general agreement between the theoretical models and the experiments. The errors introduced in the modeling as well as the manufacturing processes are discussed and taken into consideration in the design theories. This work provides a guide line for future applications of 3D re-entrant auxetic structures such as sandwich panel applications. It provides a methodology forfuture designs of other periodic cellular structures. 

 

Conventional Machining Methods for Rapid Prototyping and Direct Manufacturing

Zhi Yang, Richard A. Wysk, Sanjay Joshi
Department of Industrial and Manufacturing Engineering, The Pennsylvania State University, University Park, PA USA 16802

Matthew C. Frank, Joseph E. Petrzelka,
Department of Industrial and Manufacturing Systems Engineering, Iowa State University, Ames, IA 50011

dog_8Abstract: The material and product accuracy limitations of rapid prototyped products can often prevent the use of Rapid Prototyping (RP) processes for production of final end-use products. Conventional machining processes are well-developed technologies with the capability of employing a wide range of materials in the creation of highly accurate components. This paper presents an overview of how conventional machining processes can be used for rapid prototyping and direct manufacturing processes. The methodologies of Computer Numerical Control machining for Rapid Prototyping (CNC-RP) and Wire Electronic Discharge Machining for Rapid Prototyping (WEDM-RP) are presented in this paper. A general discussion of selection criteria and cost comparisons among both current additive RP and conventional machining approaches to rapid manufacturing is also presented.  

To read the entire paper, go to Conventional Mach for Rapid Prototyping

Rapid Planning for CNC Milling- A New Approach for Rapid Prototyping

Originally published in the Journal of Manufacturing Systems, Vol. 23/No.3, 2004

Matthew C. Frank
Department of Industrial and Manufacturing Systems Engineering, Iowa State University, Ames, IA USA

Richard A. Wysk and Sanjay Joshi,
Department of Industrial and Manufacturing Engineering, The Pennsylvania State University, University Park, PA USA

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Abstract: This paper presents a description of how CNC milling can be used to rapidly machine a variety of parts with minimal human intervention for process planning. The methodology presented uses a layer-based approach (like traditional rapid prototyping) for the rapid, semi-automatic machining of common manufactured part geometries in a variety of materials. Parts are machined using a plurality of 2½-D toolpaths from orientations about a rotary axis. Process parameters such as the number of orientations, tool containment boundaries, and tool geometry are derived from CAD slice data. In addition, automated fixturing is accomplished through the use of sacrificial support structures added to the CAD geometry.The paper begins by describing the machining methodology and then presents a number of critical issues needed to make the process automatic and efficient. Example parts machined using this methodology are then presented and discussed.

Introduction: The cost of producing small numbers of parts has been driven by the cost required to process-engineer the part(s). Traditional computer-aided process planning (CAPP) systems have reduced the time required to plan machined parts, but the cost for one or two-of-a-kind machined parts is still dominated by the cost of planning the part. The current use of CNC machining for these small quantities of parts is further limited by special tooling costs and machine setup.

To read the entire paper, go to Rapid Planning for CNC Milling

Determining Rotational Setups from Visibility of Slice Files for Rapid CNC Machining

Matthew C. Frank
Department of Industrial and Manufacturing Systems Engineering, Iowa State University, Ames, IA USA

Richard A. Wysk and Sanjay Joshi
Department of Industrial and Manufacturing Engineering, The Pennsylvania State University, University Park, PA USA

dog_8

Abstract: A method for Rapid CNC machining is being developed in an effort to automatically create functional prototypes and parts in a wide array of materials. The method uses a plurality of simple 2½-D toolpaths from various orientations about an axis of rotation in order to machine the entire surface of a part without refixturing. It is our goal to automatically create these tool paths for machining, and eliminate the complex planning traditionally associated with CNC machining. In this paper, we consider the problem of visibility to the surface of a model that is rotated about a 4th axis. Our approach involves slicing the CAD model orthogonal to the axis of rotation. The slice geometry is used to calculate 2-D visibility maps for the set of polygons on each slice plane. The visibility data provides critical information for determining the minimum number and orientation of 2½-D toolpaths required to machine the entire surface of a part.

To read the entire paper, go to Visibility of Slice Files