published_or_final_version / abstract / toc / Civil Engineering / Master / Master of Philosophy

With the increase in the application of ultra-precision manufactured parts and the absence of much participation of researchers in ultra-high precision grinding of optical glasses which has a high rate of demand in the industries, it becomes imperative to garner a full understanding of the production of these precision optics using the above-listed technology. Single point inclined axes grinding configuration and Box-Behnken experimental design was developed and applied to the ultra-high precision grinding of BK7 glass. A high sampling acoustic emission monitoring system was implemented to monitor the process. The research tends to monitor the ultra-high precision grinding of BK7 glass using acoustic emission which has proven to be an effective sensing technique to monitor grinding processes. Response surface methodology was adopted to analyze the effect of the interaction between the machining parameters: feed, speed, depth of cut and the generated surface roughness. Furthermore, back propagation Artificial Neural Network was also implemented through careful feature extraction and selection process. The proposed models are aimed at creating a database guide to the ultra-high precision grinding of precision optics.

M.Phil. (Electrical & Electronic Engineering Science) / The need to industrialise South Africa has been an effort of government to increase manufacturing and Gross Domestic Products (GDP) while also creating decent work. Manufacturing industry has been striking with organisations closing and moving. Organisations have been established and fail to compete in the market due to lack of expertise to produce products that meet the customer`s requirements. Due to the opportunities of industrialisation in Africa the focus to develop equipment for these industries is necessary. This research objective is to develop a Systematic Approach of Product Development for Industrial Processing Equipment manufacturers that supply various organisations. The research will respond to the following question while also defining the development process:-  Will product development be helpful in industrialising South Africa and building sustainable manufacturing businesses?  Define a process feedback diagram of a systematic approach of product development to be used by industrial processing equipment? The research is done with the use of literature review form published sources which is validated by survey questions that were sent to sustainable successful organizations that supply industrial equipment. The research finding demonstrates the success phases and steps to be followed when developing product. The phases and their steps are;- 1. Marketing phase stages are Identifying Market Opportunities, Evaluating Potential Markets, Identifying Customer`s Needs and Product specification 2. Concept Development phase stages are system engineering for requirements identification & allocations, Internal & external Search of solution, concept selection and concept testing 3. System Level Design phase stages is Product Architecture 4. Detailed Design Phase stages are industrial design and design for manufacturing 5. Refinement and testing phase stages are designing for reliability, prototyping and testing. These are the phases the research focused on. The Survey revealed that success sustainable organisation have been using product development, marketing and system engineering methodologies as one of their common weapon to stay in business and grow in today’s competitive market place. This systematic approach process feedback diagram in product development has a lot of phase overlap. All phases interact even though there is still a feed process from one phase to the next. The process happens concurrently to ensure that all stages are considered at an earlier stage

Please read the abstract in the section 00front of this document / Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2004. / Mechanical and Aeronautical Engineering / unrestricted

Monitoring, diagnosis and prediction of failures play key roles in automatic supervision of machine tools. They have received much attention because of the potential for reduced maintenance expenses, down time, and an increase in the equipment utilization level. At present, signal analysis techniques are predominantly used. But methods involving system analysis are capable of providing more reliable information, especially for predictive applications of supervision. System analysis involves comprehensive analytical models combined with techniques developed in control theory, and experimental modal analysis. The primary objective of this research is to develop a methodology to monitor critical physical parameters of mechanical systems, which are difficult to measure directly. These parameters are inherent features of constitutive rigid body models. A method for computer aided model generation developed in this thesis leads to a gray box model structure by which physical parameters can be estimated from experimental data. Lagrange's energy formalism, linear algebra and homogenous transformations are used to promote parsimonious three-dimensional model building. A software environment allowing symbolic and arbitrary precision computations facilitates efficient mapping of physical properties of the actual system into specific quantities of the analytical model. Six different methods are postulated and analyzed in this thesis to estimate physical parameters such as masses, stiffnesses and damping coefficients. Implementation of this methodology is a prerequisite for the design of an on-line monitoring and diagnosis system, which can detect and predict process faults. Two mechanical systems are used to validate the proposed methods: (1) A simple multi degree-of-freedom (MDOF) system and (2) a machine tool spindle assembly. A practical application of physical parameter estimation is proposed for preload monitoring in high-speed spindles. Preload variations in the bearing can lead to thermal instability and bearing seizure. The feasibility of using accelerometers located on the spindle housing to estimate bearing preload is evaluated. The optimal environment for continuation of this research is collaboration with machine tool companies to incorporate the proposed methodology (or parts of it) into current design practices. / Graduation date: 1999

Please read the abstract (Summary) in the 00front part of this document / Thesis (PhD (Mechanical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted