Ultra-high precision grinding of BK7 glass
- Authors: Onwuka, Goodness Raluchukwu
- Date: 2016
- Subjects: Machining , Machine-tools -- Monitoring , Acoustic emission
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/5203 , vital:20820
- Description: 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.
- Full Text:
- Date Issued: 2016
- Authors: Onwuka, Goodness Raluchukwu
- Date: 2016
- Subjects: Machining , Machine-tools -- Monitoring , Acoustic emission
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/5203 , vital:20820
- Description: 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.
- Full Text:
- Date Issued: 2016
A roller test bench for the evaluation of automotive vehicle noise, vibration and harshness
- Authors: Raffler, Oliver
- Date: 2015
- Subjects: Motor vehicles -- Transmission devices -- Noise Mechanical engineering Automobiles -- Noise
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/21646 , vital:29728
- Description: The purpose of this thesis is the construction of a test bench for the assessment of the NVH behaviour of a newly manufactured VW Polo 5. This will be done in collaboration with Volkswagen South Africa. Firstly, in order to gain a better understanding of the requirements such a test bench has to fulfill, the VW Polo, the guidelines prescribed by VW as well as the actual testing procedure implemented by VW Uitenhage will be analysed. Thereafter, the main section of the thesis will deal with the construction of the test bench. As agreed upon with Volkswagen Uitenhage, a test bench will be built during the course of the studies. This test bench will allow stimulation in low frequency as well as high frequency ranges and in addition to that, a second version of the test bench with optimised costing will be derived from the first one. The second model will only allow stimulation in high frequency ranges. During the thesis, a version of the test bench, the RTB-HC, has been developed which enables the stimulation of the high and low frequencies. In addition, a cost optimized version was developed. This version will be referred as RTB-LC. This version allows only a high frequency excitation.
- Full Text:
- Date Issued: 2015
- Authors: Raffler, Oliver
- Date: 2015
- Subjects: Motor vehicles -- Transmission devices -- Noise Mechanical engineering Automobiles -- Noise
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/21646 , vital:29728
- Description: The purpose of this thesis is the construction of a test bench for the assessment of the NVH behaviour of a newly manufactured VW Polo 5. This will be done in collaboration with Volkswagen South Africa. Firstly, in order to gain a better understanding of the requirements such a test bench has to fulfill, the VW Polo, the guidelines prescribed by VW as well as the actual testing procedure implemented by VW Uitenhage will be analysed. Thereafter, the main section of the thesis will deal with the construction of the test bench. As agreed upon with Volkswagen Uitenhage, a test bench will be built during the course of the studies. This test bench will allow stimulation in low frequency as well as high frequency ranges and in addition to that, a second version of the test bench with optimised costing will be derived from the first one. The second model will only allow stimulation in high frequency ranges. During the thesis, a version of the test bench, the RTB-HC, has been developed which enables the stimulation of the high and low frequencies. In addition, a cost optimized version was developed. This version will be referred as RTB-LC. This version allows only a high frequency excitation.
- Full Text:
- Date Issued: 2015
Closed-loop temperature control of friction stir welding
- Authors: Pothier, Raymond Peter
- Date: 2015
- Subjects: Friction welding
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/10362 , vital:26656
- Description: This study develops and presents a friction stir weld (FSW) quality assurance tool based on control of weld zone temperature. Apart from correct tool geometry, tool tilt angle, traverse speed and forge force during welding, one important requirement is that the weld material be sufficiently plasticised (softened). The level of plasticisation is related to weld zone temperature which is primarily dependent on spindle speed, traverse speed and forge force. When all other conditions are correct, sufficiently plasticised material flows around and consolidates behind the tool without the production of voids in the weld. Typically, weld temperature varies along the weld length which may result in variations in weld quality. Weld zone temperature control makes constant weld zone temperature possible. In this study, thermocouple sensors were embedded in the FSW tool and a weld zone temperature control algorithm was developed. Spindle speed was the actuating mechanism for controlling weld temperature. The system was modelled and controllers were designed using Matlab tools. The system was simulated and the performance was compared to the system performance during welding. The control system ensures that the weld zone temperature can be maintained irrespective of the presence of thermal disturbances. Tensile testing was conducted which confirmed a range of temperature in which the welds resulted in consistent strength.
- Full Text:
- Date Issued: 2015
- Authors: Pothier, Raymond Peter
- Date: 2015
- Subjects: Friction welding
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/10362 , vital:26656
- Description: This study develops and presents a friction stir weld (FSW) quality assurance tool based on control of weld zone temperature. Apart from correct tool geometry, tool tilt angle, traverse speed and forge force during welding, one important requirement is that the weld material be sufficiently plasticised (softened). The level of plasticisation is related to weld zone temperature which is primarily dependent on spindle speed, traverse speed and forge force. When all other conditions are correct, sufficiently plasticised material flows around and consolidates behind the tool without the production of voids in the weld. Typically, weld temperature varies along the weld length which may result in variations in weld quality. Weld zone temperature control makes constant weld zone temperature possible. In this study, thermocouple sensors were embedded in the FSW tool and a weld zone temperature control algorithm was developed. Spindle speed was the actuating mechanism for controlling weld temperature. The system was modelled and controllers were designed using Matlab tools. The system was simulated and the performance was compared to the system performance during welding. The control system ensures that the weld zone temperature can be maintained irrespective of the presence of thermal disturbances. Tensile testing was conducted which confirmed a range of temperature in which the welds resulted in consistent strength.
- Full Text:
- Date Issued: 2015
Design of a low-cost autonomous guided cart for material handling
- Authors: Cawood, Gareth James
- Date: 2015
- Subjects: Automobiles -- Design and construction , Automobiles -- Automatic control , Vehicles -- Automatic control
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: vital:9655
- Description: This dissertation covers the design and manufacture of an autonomous guided cart (AGC) for use in the material handling industry. General Motors South Africa (GMSA) requires a low-cost AGC for use in their Struandale plant. A budget of R35 000 per unit was proposed. The researcher, in collaboration with staff at GM, compiled a list of engineering requirements for the AGC. After research into the unique problems of the project, an examination of a previous design attempt by staff of GM Thailand, the researcher developed a new design, the subject of this report. Different solutions for each design problem were investigated before the design was finalised. A three-wheeled vehicle was designed making use of two motors in a differential-drive setup to control motion. Navigation is via a line-following mechanism, using an induction sensor-array in conjunction with a pre-laid metallic strip. To aid the design, the system was modelled to understand the different control elements at play. The researcher developed software for several aspects of the design: for the PLC controlling the system and motors; for a microcontroller that communicates with the PLC and a wireless module; for a computer server that communicates with a second wireless device, receiving information from the PLC; and a web interface to view this information. These form the SCADA integration of the project. The final product meets the GMSA specifications. It is a robot capable of towing a trolley of mass not exceeding 350 kg. While the robot is able to navigate a pre-laid route, it cannot reliably stop at marked locations. It is possible to monitor the system via a web-interface. The robot is capable of operating for an entire 8-hour shift before the batteries need to be recharged. The total cost of the prototype was R26 340.
- Full Text:
- Date Issued: 2015
- Authors: Cawood, Gareth James
- Date: 2015
- Subjects: Automobiles -- Design and construction , Automobiles -- Automatic control , Vehicles -- Automatic control
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: vital:9655
- Description: This dissertation covers the design and manufacture of an autonomous guided cart (AGC) for use in the material handling industry. General Motors South Africa (GMSA) requires a low-cost AGC for use in their Struandale plant. A budget of R35 000 per unit was proposed. The researcher, in collaboration with staff at GM, compiled a list of engineering requirements for the AGC. After research into the unique problems of the project, an examination of a previous design attempt by staff of GM Thailand, the researcher developed a new design, the subject of this report. Different solutions for each design problem were investigated before the design was finalised. A three-wheeled vehicle was designed making use of two motors in a differential-drive setup to control motion. Navigation is via a line-following mechanism, using an induction sensor-array in conjunction with a pre-laid metallic strip. To aid the design, the system was modelled to understand the different control elements at play. The researcher developed software for several aspects of the design: for the PLC controlling the system and motors; for a microcontroller that communicates with the PLC and a wireless module; for a computer server that communicates with a second wireless device, receiving information from the PLC; and a web interface to view this information. These form the SCADA integration of the project. The final product meets the GMSA specifications. It is a robot capable of towing a trolley of mass not exceeding 350 kg. While the robot is able to navigate a pre-laid route, it cannot reliably stop at marked locations. It is possible to monitor the system via a web-interface. The robot is capable of operating for an entire 8-hour shift before the batteries need to be recharged. The total cost of the prototype was R26 340.
- Full Text:
- Date Issued: 2015
Single event upset testing of flash based field programmable gate arrays
- Authors: Potgieter, Juan-Pierre
- Date: 2015
- Subjects: Field programmable gate arrays
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/12520 , vital:27083
- Description: In the last 50 years microelectronics have advanced at an exponential rate, causing microelectronic devices to shrink, have very low operating voltages and increased complexities; all this has made circuits more sensitive to various kinds of failures. These trends allowed soft errors, which up until recently was just a concern for space application, to become a major source of system failures of electronic products. The aim of this research paper was to investigate different mitigation techniques that prevent these soft errors in a Video Graphics Array (VGA) controller which is commonly used in projecting images captured by cameras. This controller was implemented on a Flash Based Field Programmable Gate array (FPGA). A test set-up was designed and implemented at NRF iThemba LABS, which was used to conduct the experiments necessary to evaluate the effectiveness of different mitigation techniques. The set-up was capable of handling multiple Device Under Tests (DUT) and had the ability to change the angle of incidence of each DUT. The DUTs were radiated with a 66MeV proton beam while the monitoring equipment observed any errors that had occurred. The results obtained indicated that all the implemented mitigation techniques tested on the VGA system improved the system’s capability of mitigating Single Event Upsets (SEU). The most effective mitigation technique was the OR-AND Multiplexer Single Event Transient (SET) filter technique. It was thus shown that mitigation techniques are viable options to prevent SEU in a VGA controller. The permanent SEU testing set-up which was designed and manufactured and was used to conduct the experiments, proved to be a practical option for further microelectronics testing at iThemba LABS.
- Full Text:
- Date Issued: 2015
- Authors: Potgieter, Juan-Pierre
- Date: 2015
- Subjects: Field programmable gate arrays
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/12520 , vital:27083
- Description: In the last 50 years microelectronics have advanced at an exponential rate, causing microelectronic devices to shrink, have very low operating voltages and increased complexities; all this has made circuits more sensitive to various kinds of failures. These trends allowed soft errors, which up until recently was just a concern for space application, to become a major source of system failures of electronic products. The aim of this research paper was to investigate different mitigation techniques that prevent these soft errors in a Video Graphics Array (VGA) controller which is commonly used in projecting images captured by cameras. This controller was implemented on a Flash Based Field Programmable Gate array (FPGA). A test set-up was designed and implemented at NRF iThemba LABS, which was used to conduct the experiments necessary to evaluate the effectiveness of different mitigation techniques. The set-up was capable of handling multiple Device Under Tests (DUT) and had the ability to change the angle of incidence of each DUT. The DUTs were radiated with a 66MeV proton beam while the monitoring equipment observed any errors that had occurred. The results obtained indicated that all the implemented mitigation techniques tested on the VGA system improved the system’s capability of mitigating Single Event Upsets (SEU). The most effective mitigation technique was the OR-AND Multiplexer Single Event Transient (SET) filter technique. It was thus shown that mitigation techniques are viable options to prevent SEU in a VGA controller. The permanent SEU testing set-up which was designed and manufactured and was used to conduct the experiments, proved to be a practical option for further microelectronics testing at iThemba LABS.
- Full Text:
- Date Issued: 2015
Total ionizing dose and single event upset testing of flash based field programmable gate arrays
- Authors: Van Aardt, Stefan
- Date: 2015
- Subjects: Field programmable gate arrays Application-specific integrated circuits
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/12548 , vital:27090
- Description: The effectiveness of implementing field programmable gate arrays (FPGAs) in communication, military, space and high radiation environment applications, coupled with the increased accessibility of private individuals and researchers to launch satellites, has led to an increased interest in commercial off the shelf components. The metal oxide semiconductor (MOS) structures of FPGAs however, are sensitive to radiation effects which can lead to decreased reliability of the device. In order to successfully implement a FPGA based system in a radiation environment, such as on-board a satellite, the single event upset (SEU) and total ionizing dose (TID) characteristics of the device must first be established. This research experimentally determines a research procedure which could accurately determine the SEU cross sections and TID characteristics of various mitigation techniques as well as control circuits implemented in a ProASIC3 A3P1000 FPGA. To gain an understanding of the SEU effects of the implemented circuits, the test FPGA was irradiated by a 66MeV proton beam at the iTemba LABS facility. Through means of irradiation, the SEU cross section of various communication, motor control and mitigation schemes circuits, induced by high energy proton strikes was investigated. The implementation of a full global triple modular redundancy (TMR) and a combination of TMR and a AND-OR multiplexer filter was found to most effectively mitigate SEUs in comparison to the other techniques. When comparing the communication and motor control circuits, the high frequency I2C and SPI circuits experienced a higher number of upsets when compared to a low frequency servo motor control circuit. To gain a better understanding of the absorbed dose effects, experimental TID testing was conducted by irradiating the test FPGA with a cobalt-60 (Co-60) source. An accumulated absorbed dose resulted in the fluctuation of the device supply current and operating voltages as well as resulted in output errors. The TMR and TMR filtering combination mitigation techniques again were found to be the most effective methods of mitigation.
- Full Text:
- Date Issued: 2015
- Authors: Van Aardt, Stefan
- Date: 2015
- Subjects: Field programmable gate arrays Application-specific integrated circuits
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/12548 , vital:27090
- Description: The effectiveness of implementing field programmable gate arrays (FPGAs) in communication, military, space and high radiation environment applications, coupled with the increased accessibility of private individuals and researchers to launch satellites, has led to an increased interest in commercial off the shelf components. The metal oxide semiconductor (MOS) structures of FPGAs however, are sensitive to radiation effects which can lead to decreased reliability of the device. In order to successfully implement a FPGA based system in a radiation environment, such as on-board a satellite, the single event upset (SEU) and total ionizing dose (TID) characteristics of the device must first be established. This research experimentally determines a research procedure which could accurately determine the SEU cross sections and TID characteristics of various mitigation techniques as well as control circuits implemented in a ProASIC3 A3P1000 FPGA. To gain an understanding of the SEU effects of the implemented circuits, the test FPGA was irradiated by a 66MeV proton beam at the iTemba LABS facility. Through means of irradiation, the SEU cross section of various communication, motor control and mitigation schemes circuits, induced by high energy proton strikes was investigated. The implementation of a full global triple modular redundancy (TMR) and a combination of TMR and a AND-OR multiplexer filter was found to most effectively mitigate SEUs in comparison to the other techniques. When comparing the communication and motor control circuits, the high frequency I2C and SPI circuits experienced a higher number of upsets when compared to a low frequency servo motor control circuit. To gain a better understanding of the absorbed dose effects, experimental TID testing was conducted by irradiating the test FPGA with a cobalt-60 (Co-60) source. An accumulated absorbed dose resulted in the fluctuation of the device supply current and operating voltages as well as resulted in output errors. The TMR and TMR filtering combination mitigation techniques again were found to be the most effective methods of mitigation.
- Full Text:
- Date Issued: 2015
The development of a segmented variable pitch small horizontal axis wind turbine with active pitch control
- Authors: Poole, Sean
- Date: 2013
- Subjects: Horizontal axis wind turbines , Wind turbines -- Environmental aspects , Wind turbines -- Aerodynamics
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: vital:9657 , http://hdl.handle.net/10948/d1020583
- Description: Small scale wind turbines operating in an urban environment produce dismal amounts of power when compared to their expected output [1-4]. This is largely due to the gusty wind conditions found in an urban environment, coupled with the fact that the wind turbines are not designed for these conditions. A new concept of a Segmented Variable Pitch (SVP) wind turbine has been proposed, which has a strong possibility to perform well in gusty and variable wind conditions. This dissertation explains the concept of a SVP wind turbine in more detail and shows analytical and experimental results relating to this concept. Also, the potential benefits of the proposed concept are mentioned. The results from this dissertation show that this concept has potential with promising results on possible turbine blade aerofoil configurations. Scaled model tests were completed and although further design optimisation is required, the tests showed good potential for the SVP concept. Lastly a proof-of-concept full scale model was manufactured and tested to prove scalability to full size from concept models. Along with the proof-of-concept full scale model, a wireless control system (to control the blade segments) was developed and tested.
- Full Text:
- Date Issued: 2013
- Authors: Poole, Sean
- Date: 2013
- Subjects: Horizontal axis wind turbines , Wind turbines -- Environmental aspects , Wind turbines -- Aerodynamics
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: vital:9657 , http://hdl.handle.net/10948/d1020583
- Description: Small scale wind turbines operating in an urban environment produce dismal amounts of power when compared to their expected output [1-4]. This is largely due to the gusty wind conditions found in an urban environment, coupled with the fact that the wind turbines are not designed for these conditions. A new concept of a Segmented Variable Pitch (SVP) wind turbine has been proposed, which has a strong possibility to perform well in gusty and variable wind conditions. This dissertation explains the concept of a SVP wind turbine in more detail and shows analytical and experimental results relating to this concept. Also, the potential benefits of the proposed concept are mentioned. The results from this dissertation show that this concept has potential with promising results on possible turbine blade aerofoil configurations. Scaled model tests were completed and although further design optimisation is required, the tests showed good potential for the SVP concept. Lastly a proof-of-concept full scale model was manufactured and tested to prove scalability to full size from concept models. Along with the proof-of-concept full scale model, a wireless control system (to control the blade segments) was developed and tested.
- Full Text:
- Date Issued: 2013
An in-line measuring technique with tool error detection in an automotive production line
- Authors: Viol, Florian
- Date: 2010
- Subjects: Automobile industry and trade -- Quality control
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: vital:9647 , http://hdl.handle.net/10948/1327 , Automobile industry and trade -- Quality control
- Description: The modern automobile industry faces an increasing demand on personalized high quality products. In order to stay competitive the automobile manufacturers have to ensure the customers high quality demands. With the increasing amount of applied parts and components manufacturing processes are becoming more complex. The recent quality assurance of the manufacturers considers only the product quality. Furthermore are with the recent quality assurance methods only punctual integrations of quality assurance tools in production chains possible. These limitations cause a large quality control loop. This leads in case of defective parts to an enormous time and money effort to track the cause for the defect. This project presents an innovative measurement strategy of quality assurance within the modern automobile production which will minimize the control loop and identify the tool causing the defect in the part. It highlights the possibility to integrate equipment for quality assurance directly into the production cell itself and analyse the geometrical conditions within the manufacturing processes. The result of this thesis is a fully automated prototype which is installed into the actual production of the Volkswagen Golf assembly. The prototype system consists on the one hand out of different on the market free available hardware and software components. On the other hand there are specifically for this prototype developed hardware components and software tools. For the first time it is possible to inspect the geometrical conditions of one tool continuously during production and identify, if occurring, deviations in the tool in position direction and size. The installation of similar systems in the production will minimize the control loops of the production. The chance of early recognition of errors will reduce the efforts and cost of error backtracking. In ideal conditions this instrument will identify defective tools before a product is manufactured. This innovative quality tool is the ideal addition to the current quality assurance and is the first link between the product quality and the geometrical conditions of the tools.
- Full Text:
- Date Issued: 2010
- Authors: Viol, Florian
- Date: 2010
- Subjects: Automobile industry and trade -- Quality control
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: vital:9647 , http://hdl.handle.net/10948/1327 , Automobile industry and trade -- Quality control
- Description: The modern automobile industry faces an increasing demand on personalized high quality products. In order to stay competitive the automobile manufacturers have to ensure the customers high quality demands. With the increasing amount of applied parts and components manufacturing processes are becoming more complex. The recent quality assurance of the manufacturers considers only the product quality. Furthermore are with the recent quality assurance methods only punctual integrations of quality assurance tools in production chains possible. These limitations cause a large quality control loop. This leads in case of defective parts to an enormous time and money effort to track the cause for the defect. This project presents an innovative measurement strategy of quality assurance within the modern automobile production which will minimize the control loop and identify the tool causing the defect in the part. It highlights the possibility to integrate equipment for quality assurance directly into the production cell itself and analyse the geometrical conditions within the manufacturing processes. The result of this thesis is a fully automated prototype which is installed into the actual production of the Volkswagen Golf assembly. The prototype system consists on the one hand out of different on the market free available hardware and software components. On the other hand there are specifically for this prototype developed hardware components and software tools. For the first time it is possible to inspect the geometrical conditions of one tool continuously during production and identify, if occurring, deviations in the tool in position direction and size. The installation of similar systems in the production will minimize the control loops of the production. The chance of early recognition of errors will reduce the efforts and cost of error backtracking. In ideal conditions this instrument will identify defective tools before a product is manufactured. This innovative quality tool is the ideal addition to the current quality assurance and is the first link between the product quality and the geometrical conditions of the tools.
- Full Text:
- Date Issued: 2010
Tool wear monitoring in end milling of mould steel using acoustic emission
- Authors: Olufayo, Oluwole Ayodeji
- Subjects: Acoustic emission testing , Tool-steel
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: vital:9651 , http://hdl.handle.net/10948/d1014688
- Description: Today’s production industry is faced with the challenge of maximising its resources and productivity. Tool condition monitoring (TCM) is an important diagnostic tool and if integrated in manufacturing, machining efficiency will increase as a result of reducing downtime resulting from tool failures by intensive wear. The research work presented in the study highlights the principles in tool condition monitoring and identifies acoustic emission (AE) as a reliable sensing technique for the detection of wear conditions. It reviews the importance of acoustic emission as an efficient technique and proposes a TCM model for the prediction of tool wear. The study presents a TCM framework to monitor an end-milling operation of H13 tool steel at different cutting speeds and feed rates. For this, three industrial acoustic sensors were positioned on the workpiece. The framework identifies a feature selection, extraction and conditioning process and classifies AE signals using an artificial neural network algorithm to create an autonomous system. It concludes by recognizing the mean and rms features as viable features in the identification of tool state and observes that chip coloration provides direct correlation to the temperature of machining as well as tool condition. This proposed model is aimed at creating a timing schedule for tool change in industries. This model ultimately links the rate of wear formation to characteristic AE features.
- Full Text:
- Authors: Olufayo, Oluwole Ayodeji
- Subjects: Acoustic emission testing , Tool-steel
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: vital:9651 , http://hdl.handle.net/10948/d1014688
- Description: Today’s production industry is faced with the challenge of maximising its resources and productivity. Tool condition monitoring (TCM) is an important diagnostic tool and if integrated in manufacturing, machining efficiency will increase as a result of reducing downtime resulting from tool failures by intensive wear. The research work presented in the study highlights the principles in tool condition monitoring and identifies acoustic emission (AE) as a reliable sensing technique for the detection of wear conditions. It reviews the importance of acoustic emission as an efficient technique and proposes a TCM model for the prediction of tool wear. The study presents a TCM framework to monitor an end-milling operation of H13 tool steel at different cutting speeds and feed rates. For this, three industrial acoustic sensors were positioned on the workpiece. The framework identifies a feature selection, extraction and conditioning process and classifies AE signals using an artificial neural network algorithm to create an autonomous system. It concludes by recognizing the mean and rms features as viable features in the identification of tool state and observes that chip coloration provides direct correlation to the temperature of machining as well as tool condition. This proposed model is aimed at creating a timing schedule for tool change in industries. This model ultimately links the rate of wear formation to characteristic AE features.
- Full Text:
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