Product Focused Freeform Fabrication Education

Presented in this paper is our experience of teaching freeform fabrication to students at the Missouri University of Science and Technology, and to high school students and teachers. The emphasis of the curriculum is exposing students to rapid product development technologies with the goal of creating awareness to emerging career opportunities in CAD/CAM. Starting from solid modeling, principles of freeform fabrication, to applications of rapid prototyping and manufacturing in industry sponsored product development projects, students can learn in-depth freeform fabrication technologies. Interactive course content with hands-on experience for product development is the key towards the success of the program.Mechanical Engineerin

A Review of Layer Based Manufacturing Processes for Metals

The metal layered manufacturing processes have provided industries with a fast method to build functional parts directly from CAD models. This paper compares current metal layered manufacturing technologies from including powder based metal deposition, selective laser sinstering (SLS), wire feed deposition etc. The characteristics of each process, including its industrial applications, advantages/disadvantages, costs etc are discussed. In addition, the comparison between each process in terms of build rate, suitable metal etc. is presented in this paper.Mechanical Engineerin

Experimental investigation on low-frequency vibration assisted micro-WEDM of Inconel 718

AbstractThe micro-wire electric discharge machining (micro-WEDM) has emerged as the popular micromachining processes for fabrication of micro-features. However, the low machining rate and poor surface finish are restricting wide applications of this process. Therefore, in this study, an attempt was made to improve machining rate of micro-WEDM with low-frequency workpiece vibration assistance. The gap voltage, capacitance, feed rate and vibrational frequency were chosen as control factors, whereas, the material removal rate (MRR) and kerf width were selected as performance measures while fabricating microchannels in Inconel 718. It was observed that in micro-WEDM, the capacitance is the most significant factor affecting both MRR and kerf width. It was witnessed that the low-frequency workpiece vibration improves the performance of micro-WEDM by improving the MRR due to enhanced flushing conditions and reduced electrode-workpiece adhesion

Experimental and Numerical Analysis of Angular Error in Taper Cutting Using Wire Electrical Discharge Machining

Today, there are far greater demands for higher precision in machining, use fewer tools and ease of operation. Wire electro discharge machining (WEDM) is one, mostly acceptable non-conventional machining processes, using fewer tools; ease machining and producing extreme accurate shapes in hard materials those using in the tooling industry where the extreme precision is required and complexly determines such as extrusion dies in wear-resistant materials, cutting dies, etc. Wire EDM Taper cutting took forward the generation of inclined ruled surfaces, and it is eminently more important in the manufacturing of tooling requiring draft angles. The required angle is reached by applying a relative moment between the lower guide and the upper guide. Deformation arises in the wire, during the machining of taper cutting using Wire EDM. Due to that deformation in the wire, effected to the ruled inclination of machined parts. Such circumstances cause a dimensional error, loss of tolerances and less precision that can prime to the rejection of high added value tooling. To predict the deformation of wire by considering contact mechanics, properties of wire, properties of the guide, boundary conditions, typically used in taper cutting operations, has been taking into the account. FEM is needed to reduce the experimental cost and lack of time consumption and to give a more common approach to the problem. Finite Element Model (FEM) has been used to find out the deformation occurs during wire EDM process by changing the wire parameters like wire tension, wire diameter, taper angle and wire length, which is generally considering in taper cutting. This result intends to give you better understanding shows that taper angle and wire length are the most effective parameters in taper cutting process. Taguchi’s L16 orthogonal array is used to reduce the experimental runs. Traditional Taguchi approach is insufficient to solve a multi-response optimization problem. In order to overcome this limitation, utility theory has been implemented, to convert multi-responses into single equivalent response called overall utility index. Both the results, FEM and experimental have been checked

Metals AM Design for Manufacturing

We are looking to improve upon the current post processing techniques for metal additive manufacturing (AM). This project, sponsored by Lawrence Livermore National Laboratory (LLNL), will investigate ways to improve the design of stainless steel 316 parts made by AM, and how these designs will help with post processing techniques. We hope that the findings regarding stainless steel will apply to to improve the AM and post processing handshake in general. In particular, the project will focus on including different features in different basic part design shapes to aid in fixturing and post-processing of the part made by AM. This will largely focus on including features for kinematic mounting that can be used to fixture the part in a machine for post processing or for inspection. Kinematic mounts will be added to parts that are to be milled and extension will be added to parts processed by the mill. This type of mounting can improve the accuracy of the part orientation in the machines as well as making positioning of the part more easily repeatable. Various ways of incorporating these mounts into the part design will be tested with post-processing to determine the most beneficial configuration. The information gathered will be used to create a design guide for LLNL to use with their AM processes when determining which type of mounting system would be the most useful in each situation

STEP COMPLIANT APPROACH FOR TURN-MILL OPERATIONS

Current machine tools have incurred challenges on limitation such as part programming complexity of G and M code, weak integration of digital machine tools and coverage of universal data modeling for product and manufacturing resources. In response to this manufacturing system requirement, Standard for Exchange of Product data (STEP) and its implementation on developing an interface for the next generation of machine tool controllers (STEP-NC) has become a concern of research interest and performed on basic manufacturing technology limited to a unit domain such as turning, milling or Wire EDM. Therefore; extending this STEP implementation on multipurpose machine tools such as turn-mill machines is mandatory since the machines are the main component in these industries. The research work offers a STEP-NC compliant interface supporting turn-mill machining environment identified as SCSTMO

Force Sensing in Arthroscopic Instruments using Fiber Bragg Gratings

Minimally-invasive surgery has revolutionized many medical procedures; however, it also impedes the ability to feel the interaction between the surgical tool and the anatomical part being operated on. In order to address this problem, it is necessary to obtain accurate measurements of the interaction forces exerted on the surgical tools during surgery. These forces can then be manifested to the surgeon via a haptic device or presented visually (visual-force feedback). This thesis describes the use of a fiber optic device to measure and display to the surgeon interaction forces acting on an arthroscopic tool. The sensorization of the tool involves a simple, highly efficient and robust design and is ideally suited for use in a surgical training environment aimed at narrowing the gap between trainees and expert surgeons before the trainees proceed to their first surgery in vivo. The major advantages of using fiber optics include their small size, their local simplicity, their ease of sterilization, and their high sensitivity. In this thesis, a complete low-cost sensing solution is described, including 1) the use of fiber Bragg grating and long period grating sensors, 2) design of a low-cost optical interrogator, 3) high resolution electronic signal processing, and 4) fabrication of the tool using wire EDM, CNC, and 3D metal sintering technologies. The full design of an arthroscopic grasper is presented, along with the preliminary design and manufacturing of an arthroscopic probe and shaver. The designed low-cost system was compared with a commercially-available optical interrogator. The calibration and experimental results for this system are presented and discussed for accuracy and performance of the sensorized tool before and after an axial element was added for increased sensitivity. Sources of error and methods of improvement for the optical system, arthroscopic tool, and testing procedures are discussed to inform the design of future generations of these instruments

CAD/CAM integration based on machining features for prismatic parts

The development of CAD and CAM technology has significantly increased efficiency in each individual area. The independent development, however, greatly restrained the improvement of overall efficiency from design to manufacturing. The simple integration between CAD and CAM systems has been achieved. Current integrated CAD/CAM systems can share the same geometry model of a product in a neutral or proprietary format. However, the process plan information of the product from CAPP systems cannot serve as a starting point for CAM systems to generate tool paths and NC programs. The user still needs to manually create the machining operations and define geometry, cutting tool, and various parameters for each operation. Features play an important role in the recent research on CAD/CAM integration. This thesis investigated the integration of CAD/CAM systems based on machining features. The focus of the research is to connect CAPP systems and CAM systems by machining features, to reduce the unnecessary user interface and to automate the process of tool path preparation. Machining features are utilized to define machining geometries and eliminate the necessity of user interventions in UG. A prototype is developed to demonstrate the CAD/CAM integration based on machining features for prismatic parts. The prototype integration layer is implemented in conjunction with an existing CAPP system, FBMach, and a commercial CAD/CAM system, Unigraphics. Not only geometry information of the product but also the process plan information and machining feature information are directly available to the CAM system and tool paths can be automatically generated from solid models and process plans

STEP-NC-compliant implementation to support mixed-control technologies applied to stone-processing machines based on industrial automation standards

STEP-NC (Standard for the Exchange of Product Model Data–Numerical Control) for metal milling and turning is not implemented by industrial computer numerical controllers. Solutions reported are prototypes based on post-processing in G-code. Moreover, minority machining processes, such as stone cutting, have not yet been contemplated in the STEP-NC standard. This article takes that sector as a use case. An extended STEP-NC model for circular saw stone-cutting operations is proposed, and a prototype automation implementation is developed to work with this extended model. This article shows how modern technological resources for coordinated axes control provided by many industrial controllers for the automation of general-purpose machines can speed up the processes of implementing STEP-NC numerical controllers. This article proposes a mixed and flexible approach for STEP-NC-based machine automation, where different strategies can coexist when it comes to executing STEP-NC machining files, so controllers do not need to implement the standard in an exhaustive way for all the possible features, but only at selected ones when convenient. This is demonstrated in a prototype implementation which is able to process STEP-NC product files with mixed-feature types: standard milling and non-standard sawblade features for stone processing