Digital control of an electro discharge machining (EDM) system

This thesis presents a model of the complete Electro Discharge Machining (EDM) system and the design and implementation of a digital controller for the servomotor control and the gap voltage and current pulse power generator. A Matlab/Simulink simulation is used to investigate the EDM system model behaviour and based on the simulation results, a compensated EDM control system is designed. Simulation studies were also earned out to predict the material removal rate of a steel workpiece in mm3/min . The control software of the EDM control process and servo system control was performed mainly in software with minimal hardware implementation. The control hardware consists of an eZdsp, userinterface device and analogue signal processing and interfacing circuit. The eZdsp communicates with the user-interface device by sending the information/instruction to the LCD screen while the user-interface device uses push button switches to communicate with the eZdsp. It is shown that one DSP microcontroller can be used to provide the control functions for the EDM system. The experimental studies of the Electro Discharge Machining process using a copper electrode, a graphite electrode and steel workpiece materials are presented in tabular and graphical forms. The analysis of the experimental results show that the material removal rate is influenced by the process parameters such as the gap current Igap• gap voltage V arc. pulse on-time Ion, and sparking frequency F, as well as the material properties of the electrode and the workpiece. Comparison studies between simulation and experimental results show reasonable agreement. Further improvement was made to the EDM process model based on the comparison studies. As a result, the predicted material removal rate using the improved EDM process model shows better agreement with experimental results.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

DIFFERENTIAL EVOLUTION FOR OPTIMIZATION OF PID GAIN IN ELECTRICAL DISCHARGE MACHINING CONTROL SYSTEM

ABSTRACT PID controller of servo control system maintains the gap between Electrode and workpiece in Electrical Dis- charge Machining (EDM). Capability of the controller is significant since machining process is a stochastic phenomenon and physical behaviour of the discharge is unpredictable. Therefore, a Proportional Integral Derivative (PID) controller using Differential Evolution (DE) algorithm is designed and applied to an EDM servo actuator system in order to find suitable gain parameters. Simulation results verify the capabilities and effectiveness of the DE algorithm to search the best configuration of PID gain to maintain the electrode position. Keywords: servo control system; electrical discharge machining; proportional integral derivative; con- troller tuning; differential evolution

Electrical Discharge Machining Flyback Converter using UC3842 Current Mode PWM Controller

This paper presents a current mode Pulse Width Modulation (PWM) controlled Flyback converter using UC3842 for Electrical Discharge Machining current generator control circuit. Circuit simplicity and high efficiency can be achieved by a Flyback converter with current mode PWM controller. The behaviors of the system's operation is analyzed and discussed by varying the load resistance. Matlab software is used to simulate the Flyback converter where a prototype has been built and tested to verify it's performance

Mathematical model of electrical discharge machining pulse profile

Electrical Discharge Machining (EDM) is a non-conventional manufacturing process where the removal of the unwanted materials is performed without a direct contact between the electrode and workpiece. This paper reports the mathematical model of EDM pulses that focuses on open circuit and normal discharge of circuit condition. The model is based on the equivalent electrical model of voltage and current control where the normal discharge model employs ignition delay of 4μs, 10μs and 16μs. By applying Kirchhoff’s voltage law, the voltage gap of an open circuit can be expressed according to a closed-loop network with zero current flow. As a result, the developed mathematical model capables to represent the pulse profile in EDM machining process

Consistent machining of electrical discharge machining power supply towards hip implant surface texturing

Electrical Discharge Machining, EDM is one of the technologies used for surface texturing such as the embedded micro-dimples on the metallic acetabular cup. During the machining process, changes in the gap distance may lead to load changes from open to short circuit. Limiting the load current under short circuit conditions and load voltage under open circuit conditions is the requirement in this system. Power supply is one of the elements that controls the process parameters which is related to improve the machining condition as well as Material Removal Rate (MRR). A considerable number of power supply design method were proposed for various EDM application. This research proposed a Switch Mode Power Supply method implementing new design of Flyback power supply which can stabilize the voltage during open circuit condition as well as during discharge condition. Experimental studies were conducted to verify the capability of Flyback power supply by machining eight micro-dimples in lower position and twelve micro-dimples in upper position, both in circular arrangement on metallic acetabular cup. Research conducted shows that the Flyback power supply improve the consistency of MRR when compared to Linear power supply. This may help to predict the machining time, thus improving the production of microdimples in required time

Performance Evaluation of Rain Attenuation Models in a Tropical Station

The non-uniformity of rainfall in both the horizontal and vertical directions makes the estimation of slant path attenuation complex. At frequencies above 10 GHz, the effects of attenuation and noise induced by rain are quite significant. One year satellite attenuation data were sourced from Malaysia East Asia Satellite at Ku frequency band; using ASTRO beacon signals to monitor and measure the slant path rain rate and attenuation at Universiti Teknologi Malaysia, Skudai. Four years’ one minute rain rate ground data at 0.01% of time exceeded were collected using rain gauge. The attenuation exceeded for other percentages of the time was obtained using statistical methods. Different rain attenuation prediction models were investigated and their performances compared. The validation results clearly suggested that the Breakpoint attenuation prediction model produced better results when compared with other models of interest.DOI:http://dx.doi.org/10.11591/ijece.v4i5.658

Underwater Channel Characterization to Design Wireless Sensor Network by Bellhop

Acoustic underwater link due to low attenuation is employed for underwater sensor network (UWSN). Due to water changing physical properties and different environmental conditions, the sound propagation for every underwater channel are different. So, the most important parameters to design reliable UWSN are: the shadow zone determination, optimum nodes placement, high signal to noise ratio and more power efficiency of nodes. This paper simulates underwater channel for 7 KHz carrier frequency, with measured physical water properties and remote sensing data. Based on defined scenario, the research determines optimum nodes placement and link budget analysis based on bottom to surface acoustic link. The paper utilizes Bellhop acoustic toolbox as a simulator, GeoMapApp program to collects bathymetry data and Aviso+ database to determine wind speed on sea surface. As a result the paper based on simulation of sound propagation in channel and transmission loss determination in depth and range, finds the optimum nodes positions and link budget calculation to prove the results

Flyback converter of electrical discharge machining power supply: application to surface texturing

Electrical Discharge Machining, EDM is one of non-conventional machining process that is currently applied for surface texturing. Power supply is one of the components in EDM that control process parameters which will directly influence the machining condition as well as Material Removal Rate (MRR). In this study, Flyback converter has been proposed as the new power supply. An experimental studies were conducted to verify the performance of Flyback converter by machining twenty micro-dimples in circular arrangement on metallic acetabular cup. Material removal are calculated by weighing the workpiece before and after machining. The results show a consistent value of material removal when Flyback converter is applied compared to Linear power supply. Therefore, Flyback converter is highly recommendation to be used as EDM power supply

Dynamic behaviour of EDM system through mathematical model

Electrical discharge machining (EDM) is a stochastic machining process which widely used to generate dies and molds. However, information about the EDM process is still at the earlier stage which lead to experience many challenges for further developments. Experimental analysis is time consuming as well as a costly procedure, due to the highly stochastic and complex nature of the process. Therefore, process modeling is an alternative to reduce the experimental costs related to the technology. This research proposes method to design a mathematical model of electrical discharge machining (EDM) system. The model will be used to understand the effects of machining parameters into the dynamic behaviour of EDM system based on the sparking phases and pulse power generator

Discharge analysis of EDM pulse generator

Electrical discharge machining (EDM) is a non-conventional manufacturing process used broadly in medical applications, aerospace industry and manufacturing in hard material fields. However, information about the process is still in an unfledged stage and it has been becoming a serious obstacle to its more improvements. In this paper, spark discharge condition is studied based on the simulated model of EDM spark pulse generator system equivalent form. Simulated model is verified by comparing with a series of experimental results. Frequency response is established through simplified model of EDM system. Influence of discharge time and stable discharge current on material removal rate (MRR) and stability of the system is analysed. This study is important to select the process parameters, and uses as a guidance to design the EDM spark pulse generator system