In this study, an electrolytic micro-machining tester is employed to investigate the effects of supply voltage,electrode gap and initial machining position on the geometry of the tungsten needle. The tungsten needle to be electrolyzed is dipped in an aqueous electrolyte of 2wt % sodium hydroxide as the anode, and the stainless steel needle with a diameter of 50 £gm as the cathode(tool electrode), and the electrode gap is set to be 30 £gm.Morever,the tungsten needle can be allowed to be fixed or in the reciprocating motion. Experimental results show that when the tip diameter of stainless steel needle is less than 50 £gm, a great quantity of current density and power are generated to cause the temperature failure of the tool electrode. At a certain gap between the electrodes, the electric field is focused on the narrow range to improve its processing efficiency. Under the higher supply voltage condition, it is difficult to control the size because the diameter of tungsten rod is reduced very quickly. Under the lower supply voltage condition, the diameter of tungsten rod can be processed to smaller sizes, but it takes a long time. Therefore, in the beginning of the experiment, the tungsten rod is electrolyzed under a higher voltage to the small size, and then the supply vltage is switched to lower value to conduct the electrolysis process. Consequently, a finer and more even tungsten needle can be obtained. Experimental results show that a more even tungsten needle with the length of 600 £gm and the diameter of 4 £gm can be manufactured.

The entry part introduce into the problematic of rework processes by molding injection tools for thermoplastic. Aim is necessity of change current rework process usage by electro discharge machining (EDM) technology.The theoretical part of the thesis describes the physical essence of EDM technology, the system of production of cutting electrodes and related issues. The practical part of work compare the process of production of copper and graphite electrodes with focus on production time and costs. The production parameters of the EDM process were analyzed and the wear of copper and graphite electrodes during the production process was compared. Main result of the thesis is an evaluation of the research activity, interpretation of the results of this activity and a proposal of measures to shorten the production time of the cutting electrodes and the time of the EDM machining by these electrodes.

Diplomová práce se zabývá problematikou volby grafitového materiálu využívaného pro výrobu nástrojových elektrod při elektroerozivní obrábění. Práce je rozdělena do třech částí. Teoretická rešerše nekonvenční technologie elektroerozivního obrábění vypracovaná dle uvedených zdrojů se nachází v první části práce. Dále je v práci proveden cenový průzkum EDM grafitových materiálů nabízených v České republice a na Slovensku. Čtyři odlišné stupně kvality grafitu (od stávajícího dodavatele firmy GAMARTIS TRADE s.r.o.) a jeden měděný materiál byly podrobeny experimentu, jehož účelem bylo zjištění závislosti mezi kvalitou grafitového materiálu (cena) a přesností vyhloubené kavity, opotřebením nástrojové elektrody, časem obrábění nebo také drsností povrchu.

The master’s thesis deals with the topic of electrical discharge machining. The first part of the thesis contains a study of the die-sinking EDM. The die-sinking EDM of the silicon carbide ceramic is realized in the experimental part of the thesis. The result of this work was to explore the influence of the EDM sinking parameters, specifically pulse current, open-voltage and pulse on-time, on the machined surface. Furthermore, the analysis of the tool electrode was made. This analysis was focused on the wear in the corners, which has key influence on accuracy of the machining. The machining time was also examined.

This diploma thesis is involved in possible development of different types of milling molds coated with modern plows. The first part is devoted to an analysis of contemporary trends in forms production technology. The analysis includes the different types of machines and tools for making various kinds of molds and dies. Another part deals with design of dies for sheet metal shears. The thesis continues by design of the production procedure after heat treatment and finishing die by miling. For milling of die are designed miling tools, the NC program and the possible development of manufacturing the die using a new machining center and the possibility of production optimization. The penultimate point of the thesis is technical and economical evaluation of the direction of development and comparison of positives and negatoves of each method. At the final evaluation is all summed up.