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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

An Investigation of Kinematic Redundancy for Reduced Error in Micromilling

January 2014 (has links)
abstract: Small metallic parts of size less than 1mm, with features measured in tens of microns, with tolerances as small as 0.1 micron are in demand for the research in many fields such as electronics, optics, and biomedical engineering. Because of various drawbacks with non-mechanical micromanufacturing processes, micromilling has shown itself to be an attractive alternative manufacturing method. Micromilling is a microscale manufacturing process that can be used to produce a wide range of small parts, including those that have complex 3-dimensional contours. Although the micromilling process is superficially similar to conventional-scale milling, the physical processes of micromilling are unique due to the scale effects. These scale effects occur due to unequal scaling of the parameters from the macroscale to the microscale milling. One key example of scale effects in micromilling process is a geometrical source of error known as chord error. The chord error limits the feedrate to a reduced value to produce the features within machining tolerances. In this research, it is hypothesized that the increase of chord error in micromilling can be alleviated by intelligent modification of the kinematic arrangement of the micromilling machine. Currently, all 3-axis micromilling machines are constructed with a Cartesian kinematic arrangement with three perpendicular linear axes. In this research, the cylindrical kinematic arrangement is introduced, and an analytical expression for the chord error for this arrangement is derived. The numerical simulations are performed to evaluate the chord errors for the cylindrical kinematic arrangement. It is found that cylindrical kinematic arrangement gives reduced chord error for some types of the desired toolpaths. Then, the kinematic redundancy is introduced to design a novel kinematic arrangement. Several desired toolpaths have been numerically simulated to evaluate the chord error for kinematically redundant arrangement. It is concluded that this arrangement gives up to 5 times reduced error for all the desired toolpaths considered, and allows significant gains in allowable feedrates. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2014
3

Design and construction of a novel reconfigurable micro manufacturing cell

Al-Sharif, Rakan January 2012 (has links)
Demands for producing small components are increasing. Such components are usually produced using large-size conventional machining tools. This results in the inadequate usage of resources, including energy, space and time. In the 1990s, the concept of a microfactory was introduced in order to achieve better usage of these resources by scaling down the size of the machine tool itself. Several industries can benefit from implementing such a concept, such as the medical, automotive and electronics industries. A novel architecture for a reconfigurable micro-manufacturing cell (RMC) is presented in this research, aiming at delivering certain manufacturing strategies such as point of use (POU) and cellular manufacturing (CM) as well as several capabilities, including modularity, reconfigurability, mobility and upgradability. Unlike conventional machine tools, the proposed design is capable of providing several machining processes within a small footprint (500 mm2), yet processing parts within a volume up to 100 mm3. In addition, it delivers a rapid structure and process reconfiguration while achieving a micromachining level of accuracy. The approach followed in developing the system is highly iterative with several feedback loops. It was deemed necessary to adopt such an approach to ensure that not only was the design relevant, but also that it progresses the state-of-the-art and takes into account the many considerations in machine design. Following this approach, several design iterations have been developed before reaching a final design that is capable of delivering the required manufacturing qualities and operational performance. A prototype has been built based on the specifications of the selected design iteration, followed by providing a detailed material and components selection process and assembly method before running a performance assessment analysis of the prototype. At this stage, a correlation between the Finite Element Analysis (FEA) model and prototype has been considered, aiming at studying the level of performance of the RMC when optimising the design in the future. Then, based on the data collected during each stage of the design process, an optimisation process was suggested to improve the overall performance of the system, using computer aided design and modelling (CAD/CAM) tools to generate, analyse and optimise the design.

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