The meaning of the diploma thesis is to create a new mold plunger for injection mold using a suitable method according to the original mold plunger. The final mold part should meet the required surface parameters. The work is focused on the analysis of the original mold plunger and the experimental verification of suitable methods of production of the equivalent mold plunger.

Electrical discharge wire machining, which represents non-conventional machining technology is up on very high technological level. However, due to this type of machining many of defects are set on the material and the quality of machined surface is changed according to set parameters of machine. Complex study was created with the aim of optimization these parameters according to final quality of surface and right wire speed. This study include experiment with 33 samples, every of these samples was machined with different parameters, results of these machining were analyzed.

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<p>Electrical discharge machining (EDM) is a non-conventional machining process utilizing a series of electrical discharges to melt and vaporize workpiece material. In a wire EDM configuration wire breakage is a limiting factor in the machining productivity during the machining of workpieces with varying heights. Present methods of estimating workpiece height on-line in an effort to optimize machining parameters monitor the electrical signals for changes which may not be completely indicative of a change in workpiece height. This thesis intends to utilize acoustic emission (AE) sensors as a method for mapping the discharge location in order to estimate the workpiece height. This represents a novel approach as acoustic emission testing, while prevalent in the process monitoring of numerous conventional machining processes has yet to be significantly studied in combination with EDM.</p> <p>Another useful application of AE sensors with the EDM process under consideration is during the fast hole EDM process, where excessive wear is seen in the electrode causing true electrode length to remain uncertain. By using acoustic emission sensors to determine the true length of the electrode it could be possible to aid in the breakout detection of the electrode.</p> / Master of Applied Science (MASc)

Heat transfer technologies based on boiling refer to applications like heat pumps, waste heat recovery systems, power plants and electronic components cooling. The widespread use of boiling as the heat transfer mode is due to high heat transfer coefficients associated with the phase change from liquid to vapor. Boiling heat transfer coefficients can be further enhanced by modifying the texture or chemical composition of the interface at which boiling occurs. The objective of this research is to fabricate textured surfaces with electrical discharge machining (EDM) and investigate the enhancement in pool boiling heat transfer, concerning machining and surface characterization parameters. It is complemented by a qualitative analysis of bubble dynamics with high-speed imaging, to provide insights into the differences in boiling performance associated with the changes in surface topography. Sink electrical discharge machined surfaces demonstrated ten times higher heat transfer coefficient compared to a polished surface during these studies. / Thesis / Master of Applied Science (MASc)

L’objet de cette thèse est d’étudier un procédé de fraisage par microélectroérosion (μEE), qui est un procédé sans contact permettant d’usiner tous les matériaux durs conducteurs d’électricité à l’aide d’un micro-outil cylindrique ultrafin. Le principe consiste à créer des micro-décharges électriques entre le micro-outil et une pièce conductrice immergés dans un diélectrique liquide. En faisant parcourir à l’outil un parcours 3D, il est possible de creuser une forme complexe dans la pièce avec des détails à fort rapport d’aspect. Dans ce travail, nous avons tout d’abord amélioré un procédé d’élaboration de microoutils cylindriques ultrafins par gravure électrochimique de barreaux de tungstène. Des outils de diamètre 32,6 ± 0,3 μm sur une longueur de 3 mm ont été obtenus de manière automatique et reproductible. L’écart type a été divisé par 2 par rapport à l’état de l’art antérieur. Des outils de diamètre inférieur ont été obtenus avec une intervention de l’opérateur, et ce jusqu’à 3 μm de diamètre. Puis ces micro-outils ont été mis en oeuvre pour usiner des pièces avec le procédé de fraisage par microélectroérosion. Pour ce faire, une machine de 2ème génération a été entièrement développée sur la base de travaux antérieurs. Il a été possible d’usiner de l’acier inoxydable dans de l’eau déionisée avec des micro-outils de 3 μm de diamètre sans détérioration de l’outil. Par ailleurs, Le procédé de μEE a été caractérisé en termes de résolution d’usinage, taux d’enlèvement de matière et usure de l’outil. Un générateur de décharges original a permis d’usiner avec des micro-décharges de 1 à 10 nJ / étincelle avec une diminution très sensible de l’usure de l’outil par rapport à l’état de l’art. Un procédé original de caractérisation en ligne des décharges et de cartographie dans l’espace a aussi été développé / This work aims at studying Micro Electrical Discharge Milling (μEDM milling), which is a non-contact process allowing machining all hard and electrically conductive materials with a cylindrical ultrathin tool. The principle is based on the creation of electrical micro discharges between the tool and an electrically conductive part immersed in a liquid dielectric. By means of a 3D path, the tool machines a complex shape in the part with high aspect ratio details. In this work, we have firstly improved a process for making cylindrical ultrathin micro-tools by electrochemical etching of tungsten rods. Tools with a diameter of 32.6 ± 0.3 μm and a length of 3 mm have been obtained with an automated and reproducible process. Standard deviation has been divided by 2 by comparison with the previous state of the art. Tools with diameter as low as 3 μm have been fabricated with the help of the machine operator Then these micro-tools have been used for machining parts with the μEDM milling process. To do so, a second generation machine has been entirely developed on the basis of previous work. It has been possible to machine stainless steel in deionized water with 3 μm micro-tools without damaging the tools. In other respects, the μEDM milling process has been characterized in terms of machining resolution, material removal rate and tool wear. An innovative generator of discharges allow machining with 1 to 10 nJ / spark with a reduced tool wear by comparison to the state of the art. An innovative process for the on line characterization of discharges with spatial distribution capability has been developed

Work is focused on theoretic analisis of manufacturing precise shears tools by unconventional technology closely focused on wire electro discharge machining consideration operation costs of this metod.It is discribing development of this method, machines and tools for electrical discharge machining. It is mention facts influencing quality of cut surface during manufacturing of cutting tools, strategy of cutting workpiece, stage and quality of surface layer after WEDM as long with economic viewpoint and benefits of WEDM technology.

In this work, description of a basic principle of electro discharge machining and its technological possibilities was made. Possibilities of individual EDM machine producers and their comparison were described. Furthermore, the use of electro discharge machining in Zdas a.s. was shown. Trends in a development of the electro discharge technology are included, too.

This master’s thesis deals with technology of wire electrical discharge machining in theoretical and practical level. Theoretical part of the thesis explains in detail the principle of electrical discharge machining, describes functional parts and settings of a current wire EDM machines and also the possibility of using method for production of specific parts. Practical part of the thesis solves manufacturing of gearing on pinion manufactured by wire cutter EXCETEK V650 and statistically evaluates precision parameters on surfaces of the carriers taken by specific technological conditions with the same machine.

Wire Electrical Discharge Machining (WEDM) is a nontraditional machining process used for machining intricate shapes in high strength and temperature resistive (HSTR) materials. WEDM provides high accuracy, repeatability, and a better surface finish; however the tradeoff is a very slow machining rate. Due to the slow machining rate in WEDM, machining tasks take many hours depending on the complexity of the job. Because of this, users of WEDM try to predict machining rate beforehand so that input parameter values can be pre-programmed to achieve automated machining. However, partial success with traditional methodologies such as thermal modeling, artificial neural networks, mathematical, statistical, and empirical models left this problem still open for further research and exploration of alternative methods. Also, earlier efforts in applying the decision tree rule induction algorithms for predicting the machining rate in WEDM had limitations such as use of coarse grained method of discretizing the target and exploration of only C4.5 as the learning algorithm. The goal of this dissertation was to address the limitations reported in literature in using decision tree rule induction algorithms for WEDM. In this study, the three decision tree inductive algorithms C5.0, CART and CHAID have been applied for predicting material removal rate when the target was discretized into varied number of classes (two, three, four, and five classes) by three discretization methods. There were a total of 36 distinct combinations when learning algorithms, discretization methods, and number of classes in the target are combined. All of these 36 models have been developed and evaluated based on the prediction accuracy. From this research, a total of 21 models found to be suitable for WEDM that have prediction accuracy ranging from 71.43% through 100%. The models indentified in the current study not only achieved better prediction accuracy compared to previous studies, but also allows the users to have much better control over WEDM than what was previously possible. Application of inductive learning and development of suitable predictive models for WEDM by incorporating varied number of classes in the target, different learning algorithms, and different discretization methods have been the major contribution of this research.