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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Simulation and Control Motion Software Development for Micro Manufacturing

Bayesteh, Abdolreza 18 December 2013 (has links)
Due to increasing trends of miniaturization, components with microscale features are in high demand. Accordingly, manufacturing and measurement of small components as small as a few microns became new challenges. Micro milling and femtosecond laser machining are the most common in use cutting operations providing high accuracy and productivity. Micro milling has unique features different from traditional milling including high ratio of tool size to feature size, and constant ratio of tool edge radius to tool size [1]. Due to the mentioned differences, low stiffness of the micro mill and the complexity of the cutting mechanism at the macroscale, selection of cutting parameters are difficult [2]. Therefore, process performance in micro milling, which affects surface quality and tool life, depends on the selected cutting parameters. Also, for measuring micro components, the available dimensional control systems in the market are atomic force microscopes (AFMs) and a combination of coordinate measuring machines (CMMs) and vision systems. These are confined to the scopes of nanoscale and macroscale parts, respectively. It is difficult to justify the high cost and large size of these systems for measurement of mesoscale/microscale features and components and dimensional verification of miniature parts with 3D features. Therefore, a new cost-effective way is needed for measuring components and features in these scales. Additionally, lack of advanced CAD/CAM software for micro laser machining providing constant velocity along the tool path, is the main problem in femtosecond laser machining. In this thesis, to address the mentioned challenges, different software packages are presented to improve micro machining productivity, to provide an accurate and cost effective way of micro scanning and to bring CAD/CAM capability for micro laser machining. / Graduate / 0548 / abdolreza.bayesteh@gmail.com
2

Development of a micro-milling force model and subsystems for miniature Machine Tools (mMTs)

Goo, Chan-Seo 29 July 2011 (has links)
Nowadays, the need for three-dimensional miniaturized components is increasing in many areas, such as electronics, biomedics, aerospace and defence, etc. To support the demands, various micro-scale fabrication techniques have been further introduced and developed over the last decades, including micro-electric-mechanical technologies (MEMS and LIGA), laser ablation, and miniature machine tools (mMTs). Each of these techniques has its own benefits, however miniature machine tools are superior to any others in enabling three-dimensional complex geometry with high relative accuracy, and the capability of dealing with a wide range of mechanical materials. Thus, mMTs are emerging as a promising fabrication process. In this work, various researches have been carried out based on the mMTs. The thesis presents micro-machining, in particular, micro-milling force model and three relevant subsystems for miniature machine tools (mMTs), to enhance machining productivity/efficiency and dimensional accuracy of machined parts. The comprehensive force model that predicts micro-endmilling dynamics has been developed. Unlike conventional macro-machining, the cutting mechanism in micro-machining is complex with high level of non-linearity due to the combined effects of edge radius, size, and minimum chip thickness effect, etc., resulting in no chip formation when the chip thickness is below the minimum chip forming thickness. Instead, part of the work material deforms plastically under the edge of a tool and the rest of the material recovers elastically. The developed force model for micro-endmilling is effective to understand the micro-machining process. As a result, the micro-endmilling force model is helpful to improve the quality of machined parts. In addition, three relevant subsystems which deliver maximum machining productivity and efficiency are also introduced. Firstly, ultrasonic atomization-based cutting fluid application system is introduced. During machining, cutting fluid is required at the cutting zone for cooling and lubricating the cutting tool against the workpiece. Improper cutting fluid application leads to significantly increased tool wear, and which results in overall poor machined parts quality. For the micro-machining, conventional cooling methods using high pressure cutting fluid is not viable due to the potential damage and deflection of weak micro-cutting tools. The new atomization-based cutting fluids application technique has been proven to be quite effective in machinability due to its high level of cooling and lubricating. Secondly, an acoustic emission (AE)-based tool tip positioning method is introduced. Tool tip setting is one of the most important factors to be considered in the CNC machine tool. Since several tools with different geometries are employed during machining, overall dimensional accuracy of the machined parts are determined by accurate coordinates of each tool tip. In particular, tool setting is more important due to micro-scale involved in micro-machining. The newly developed system for tool tip positioning determines the accurate coordinates of the tool tip through simple and easy manipulation. At last, with the advance of the 3D micro-fabrication technologies, the machinable miniaturized components are getting complex in geometry, leading to increased demand on dimensional quality control. However, the system development for micro-scale parts is slow and difficult due to complicated detection devices, algorithm, and fabrication of a micro-probe. Consequently, the entire dimensional probing system tends to become bulky and expensive. A new AE-based probing system with a wire-based probe was developed to address this issue with reduced cost and size, and ease of application. / Graduate

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