Development of the UMAC-based control system with application to 5-axis ultraprecision micromilling machines

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Increasing demands from end users in the fields of optics, defence, automotive, medical, aerospace, etc. for high precision 3D miniaturized components and microstructures from a range of materials have driven the development in micro and nano machining and changed the manufacturing realm. Conventional manufacturing processes such as chemical etching and LIGA are found unfavourable or limited due to production time required and have led mechanical micro machining to grow further. Mechanical micro machining is an ideal method to produce high accuracy micro components and micro milling is the most flexible enabling process and is thus able to generate a wider variety of complex micro components and microstructures. Ultraprecision micromilling machine tools are required so as to meet the accuracy, surface finish and geometrical complexity of components and parts. Typical manufacturing requirements are high dimensional accuracy being better than 1 micron, flatness and roundness better than 50 nm and surface finish ranging between 10 and 50 nm. Manufacture of high precision components and parts require very intricate material removal procedure. There are five key components that include machine tools, cutting tools, material properties, operation variables and environmental conditions, which constitute in manufacturing high quality components and parts. End users assess the performance of a machine tool based on the dimensional accuracy and surface quality of machined parts including the machining time. In this thesis, the emphasis is on the design and development of a control system for a 5-axis bench-type ultraprecision micromilling machine- Ultra-Mill. On the one hand, the developed control system is able to offer high motion and positioning accuracy, dynamic stiffness and thermal stability for motion control, which are essential for achieving the machining accuracy and surface finish desired. On the other hand, the control system is able to undertake in-process inspection and condition monitoring of the machine tool and process. The control of multi-axis precision machines with high-speed and high-accuracy motions and positioning are desirable to manufacture components with high accuracy and complex features to increase productivity and maintain machine stability, etc. The development of the control system has focused on fast, accurate and robust positioning requirements at the machine system design stage. Apart from the mechanical design, the performance of the entire precision systems is greatly dependent on diverse electrical and electronics subsystems, controllers, drive instruments, feedback devices, inspection and monitoring system and software. There are some variables that dynamically alter the system behaviour and sensitivity to disturbance that are not ignorable in the micro and nano machining realm. In this research, a structured framework has been developed and integrated to aid the design and development of the control system. The framework includes critically reviewing the state of the art of ultraprecision machining tools, understanding the control system technologies involved, highlighting the advantages and disadvantages of various control system methods for ultraprecision machines, understanding what is required by end-users and formulating what actually makes a machine tool be an ultraprecision machine particularly from the control system perspective. In the design and development stage, the possession of mechatronic know-how is essential as the design and development of the Ultra-Mill is a multidisciplinary field. Simulation and modelling tool such as Matlab/Simulink is used to model the most suitable control system design. The developed control system was validated through machining trials to observe the achievable accuracy, experiments and testing of subsystems individually (slide system, tooling system, monitoring system, etc.). This thesis has successfully demonstrated the design and development of the control system for a 5-axis ultraprecision machine tool- Ultra-Mill, with high performance characteristics, fast, accurate, precise, etc. for motion and positioning, high dynamic stiffness, robustness and thermal stability, whereby was provided and maintained by the control system

Machining of hybrid composites

Tese de doutoramento. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 200

Development of a machine-tooling-process integrated approach for abrasive flow machining (AFM) of difficult-to-machine materials with application to oil and gas exploration componenets

This thesis was submitted for the degree of Doctor of Engineering and awarded by Brunel UniversityAbrasive flow machining (AFM) is a non-traditional manufacturing technology used to expose a substrate to pressurised multiphase slurry, comprised of superabrasive grit suspended in a viscous, typically polymeric carrier. Extended exposure to the slurry causes material removal, where the quantity of removal is subject to complex interactions within over 40 variables. Flow is contained within boundary walls, complex in form, causing physical phenomena to alter the behaviour of the media. In setting factors and levels prior to this research, engineers had two options; embark upon a wasteful, inefficient and poor-capability trial and error process or they could attempt to relate the findings they achieve in simple geometry to complex geometry through a series of transformations, providing information that could be applied over and over. By condensing process variables into appropriate study groups, it becomes possible to quantify output while manipulating only a handful of variables. Those that remain un-manipulated are integral to the factors identified. Through factorial and response surface methodology experiment designs, data is obtained and interrogated, before feeding into a simulated replica of a simple system. Correlation with physical phenomena is sought, to identify flow conditions that drive material removal location and magnitude. This correlation is then applied to complex geometry with relative success. It is found that prediction of viscosity through computational fluid dynamics can be used to estimate as much as 94% of the edge-rounding effect on final complex geometry. Surface finish prediction is lower (~75%), but provides significant relationship to warrant further investigation. Original contributions made in this doctoral thesis include; 1) A method of utilising computational fluid dynamics (CFD) to derive a suitable process model for the productive and reproducible control of the AFM process, including identification of core physical phenomena responsible for driving erosion, 2) Comprehensive understanding of effects of B4C-loaded polydimethylsiloxane variants used to process Ti6Al4V in the AFM process, including prediction equations containing numerically-verified second order interactions (factors for grit size, grain fraction and modifier concentration), 3) Equivalent understanding of machine factors providing energy input, studying velocity, temperature and quantity. Verified predictions are made from data collected in Ti6Al4V substrate material using response surface methodology, 4) Holistic method to translating process data in control-geometry to an arbitrary geometry for industrial gain, extending to a framework for collecting new data and integrating into current knowledge, and 5) Application of methodology using research-derived CFD, applied to complex geometry proven by measured process output. As a result of this project, four publications have been made to-date – two peer-reviewed journal papers and two peer-reviewed international conference papers. Further publications will be made from June 2014 onwards.Engineering and Physical Sciences Research Council (EPSRC) and the Technology Strategy Board (TSB

Rankine cycle test facility study - Technical data Final report

Vacuum environmental requirements, loop design, materials, and instrumentation for facility to be used for testing liquid metal Rankine cycle component

Liquid rocket valve components

A monograph on valves for use with liquid rocket propellant engines is presented. The configurations of the various types of valves are described and illustrated. Design criteria and recommended practices for the various valves are explained. Tables of data are included to show the chief features of valve components in use on operational vehicles

Machining Fibre Metal Laminates and Al2024-T3 aluminium alloy

The present thesis investigates the machining performance of an aerospace structural material commercially known as GLARE fibre metal laminate and its metal constituent aluminium Al2024-T3 aerospace alloy using commercially available solid carbide twist drills. The objective is to quantify the effects of the cutting parameters and two modern coolant technologies on cutting forces and a number of hole quality parameters. The generated drilling cutting forces, quality of machined hole and drilling-induced damage and defects when drilling GLARE fibre metal laminates were experimentally studied. Drilling-induced defects and damage investigated were surface roughness, burr formation at both sides of the workpiece and interlayer burr, hole size and circularity error, chip formation as well as damage described at the macro level (delamination area) using computerised tomography (CT) scan, and at the micro level (fibre matrix debonding, chipping, adhesions, cracks) using scanning electron microscopy (SEM). The experimental results have been statistically analysed using full factorial and response surface methodology statistical techniques to generate multiple regression models which makes it attractive as an indirect tool predicting the machining outputs prior the start of actual tests. Moreover, the analysis of variance (ANOVA) was employed to determine the percentage contribution of drilling parameters on cutting forces and hole quality outputs. The results indicated that the presence of coolant during the drilling process of GLARE could significantly improve hole quality. The use of cryogenic liquid nitrogen was found to eliminate the formation of waste on the borehole surface and burr formation at the hole exit. Using minimum quantity lubrication coolant was found to reduce the workpeice temperature compared to dry drilling at room temperature. Both coolants reduced the surface roughness compared to dry drilling but increased the cutting forces especially when using cryogenic liquid nitrogen. The cutting parameters results indicated that a maximum operating feed rate of 300 mm/min and a maximum spindle speed of 6000 rpm is recommended for superior hole quality results. Moreover, drilling at or below those levels of cutting parameters did not lead to severe delamination or fibre pull outs in the laminate compared to the higher cutting parameters used in the study. In addition, the fibre orientation and workpiece thickness were found to play a significant role on surface roughness and hole size but did not have a considerable impact on cutting forces due to the small thickness of glass fibre layers in the laminate. Adhesion and built up edge was found to be the main wear mechanism when drilling monolithic aluminium alloy, while adhesion and abrasion of the primary and secondary facets of the drill were identified to be the main wear process that occurs in drilling GLARE laminates

Development of the UMAC-based control system with application to 5-axis ultraprecision micromilling machines

Increasing demands from end users in the fields of optics, defence, automotive, medical, aerospace, etc. for high precision 3D miniaturized components and microstructures from a range of materials have driven the development in micro and nano machining and changed the manufacturing realm. Conventional manufacturing processes such as chemical etching and LIGA are found unfavourable or limited due to production time required and have led mechanical micro machining to grow further. Mechanical micro machining is an ideal method to produce high accuracy micro components and micro milling is the most flexible enabling process and is thus able to generate a wider variety of complex micro components and microstructures. Ultraprecision micromilling machine tools are required so as to meet the accuracy, surface finish and geometrical complexity of components and parts. Typical manufacturing requirements are high dimensional accuracy being better than 1 micron, flatness and roundness better than 50 nm and surface finish ranging between 10 and 50 nm. Manufacture of high precision components and parts require very intricate material removal procedure. There are five key components that include machine tools, cutting tools, material properties, operation variables and environmental conditions, which constitute in manufacturing high quality components and parts. End users assess the performance of a machine tool based on the dimensional accuracy and surface quality of machined parts including the machining time. In this thesis, the emphasis is on the design and development of a control system for a 5-axis bench-type ultraprecision micromilling machine- Ultra-Mill. On the one hand, the developed control system is able to offer high motion and positioning accuracy, dynamic stiffness and thermal stability for motion control, which are essential for achieving the machining accuracy and surface finish desired. On the other hand, the control system is able to undertake in-process inspection and condition monitoring of the machine tool and process. The control of multi-axis precision machines with high-speed and high-accuracy motions and positioning are desirable to manufacture components with high accuracy and complex features to increase productivity and maintain machine stability, etc. The development of the control system has focused on fast, accurate and robust positioning requirements at the machine system design stage. Apart from the mechanical design, the performance of the entire precision systems is greatly dependent on diverse electrical and electronics subsystems, controllers, drive instruments, feedback devices, inspection and monitoring system and software. There are some variables that dynamically alter the system behaviour and sensitivity to disturbance that are not ignorable in the micro and nano machining realm. In this research, a structured framework has been developed and integrated to aid the design and development of the control system. The framework includes critically reviewing the state of the art of ultraprecision machining tools, understanding the control system technologies involved, highlighting the advantages and disadvantages of various control system methods for ultraprecision machines, understanding what is required by end-users and formulating what actually makes a machine tool be an ultraprecision machine particularly from the control system perspective. In the design and development stage, the possession of mechatronic know-how is essential as the design and development of the Ultra-Mill is a multidisciplinary field. Simulation and modelling tool such as Matlab/Simulink is used to model the most suitable control system design. The developed control system was validated through machining trials to observe the achievable accuracy, experiments and testing of subsystems individually (slide system, tooling system, monitoring system, etc.). This thesis has successfully demonstrated the design and development of the control system for a 5-axis ultraprecision machine tool- Ultra-Mill, with high performance characteristics, fast, accurate, precise, etc. for motion and positioning, high dynamic stiffness, robustness and thermal stability, whereby was provided and maintained by the control system.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Mesoscale Ceramic Cylindrical Ion Trap Mass Analyzers For In Situ Sample Analysis

As wireless network devices and IOT connectivity develop, the application and demand for small, low power, in situ sensors and instruments will expand. There are continuous efforts in the miniaturization of sensors and scientific instrument systems for conventional to field deployable and rugged hand held units for personal use to extreme harsh environment applications. This work investigates mesoscale cylindrical ion trap (CIT) mass analyzer design and the benefits of CITs realized via additive manufactured metalized ceramic material systems for improved ion signal, low power performance, and extended dynamic range. Rugged monolithic miniature mass spectrometer ceramic CIT chips have been produced that have increased signal output with reduced power consumption. We have demonstrated via simulation and experiment ~80% and greater CIT ion detection efficiency, signal improvement of the percentage of analyzed ions detected, from 50% detection for conventional CIT designs. Utilizing a unique notched ring electrode design that increases the ion signal output to the detector, the electron ionization quantity and power required for mass spectrum generation and tuning was reduced by ~1 watt or 33%, as well as the required gain of the ion detector. Increased CIT ion detection efficiency effectively increases the total amount of the sample analyzed versus what is lost, thus increasing the instrument sensitivity and data collected, reducing duty cycle and power. Identical CITs of a ring electrode radius, ro = 1 mm, were fabricated from low temperature co-fired ceramic (LTCC) and the stainless steel (SS) for performance comparison and were tested in mass instability scanning and resonance ejection modes to produce Perfluorotribuytlamine (PFTBA) mass spectra. The ceramic material system offers design anFd material benefits which reduce the CIT power consumption by 29x from ~10.20 mW power consumption of the stainless steel CIT design to 0.36 mW for the ceramic CIT, as well as enabling batch fabrication, reduced cost and manufacturing defects. While the stated design and material system benefits may facilitate CIT and MS system miniaturization, and the production of the ceramic CIT chip, the proof of concept of CIT ion ejection efficiency via the notched ring electrode may enhance ion trap designs at any scale

Cumulative Index to NASA Tech Briefs, 1963 - 1966

Cumulative index of NASA Tech Briefs dealing with electrical and electronic, physical science and energy sources, materials and chemistry, life science, and mechanical innovation