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Comparative performance of late stream inoculants in grey cast iron using thermal analysis
Chyla, Ondrej ; Bouška, Ondřej (referee) ; Roučka, Jaromír (advisor)
This diploma thesis in the theoretical part deals with classification of cast iron, problems of gray cast iron production, methods of inoculation and valuation of the gray iron quality by means of thermal analysis. The aim of practical part was to investigate effectiveness of inoculation of two different inoculants using thermal analysis. In terms of mechanical properties, hardness and ultimate tensile strength were measured. Metallographic specimen were evaluating by means of image analysis software.
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Optimization of die casting technology for the casting of vacuum pump
Krňávek, Štěpán ; Kolmačka, Marek (referee) ; Roučka, Jaromír (advisor)
Diploma thesis deals with optimization of technological process casting a die cast, which is part of vacuum pump. The die cast is made from alloy AlSi9Cu3(Fe) in foundry KOVOLIT, a. s. There is a problem with inner defects at this cast. Solution of this thesis is to suggest suitable actions to minimize of incidence the defects in the cast. According to analysis of the defects in the cast these defects were classified as combination of shrinkages and gas holes. According to analysis causes of the defects are high temperature of die mould and closed air in die mould. As a result suitable actions were suggested – a change of the die mould tempering and a design adjustment of the cast. In case of implementing a new die mould in the manufacture a new gating system was designed. Suitability of the new gating system was assessed according to simulation of filling die cavity.
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Surface quenching of ductile cast iron
Neduchal, Bronislav ; Roučka, Jaromír (referee) ; Záděra, Antonín (advisor)
This diploma thesis is focused on the surface hardening of cast irons with spheroidal graphite. The work describes a theoretical analysis of the structure and properties of cast irons and individual methods suitable for surface hardening. The practical part describes the production of cast iron castings with spheroidal graphite, on which the surface hardening is performed, tensile test, hardening of produced castings by induction and laser surface hardening, preparation of samples for measuring microhardness and metallographic analysis of metal structures.
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Solidification of castings by pouring into shell moulds in vakuum furnaces
Odložil, Jan ; Ňuksa, Petr (referee) ; Roučka, Jaromír (advisor)
Heat transfer during metal pouring and its solidification in the vacuum furnace have been investigated by experiments using model set of castings of different diameters and insulations. The pouring metal was Inconel 713LC alloy based on nickel. The found data have been used for optimization of the numerical simulation of the thermal regime during the both pouring and solidification phases of the process in vacuum. Numerical simulation of the alloy structure in individual castings has been made by the CAFE module of the ProCast software and obtained results compared with the real structure. The optimized boundary conditions can be used for simulation of real castings.
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Introduction of special die lubricant - micro spraying into the conditions of high pressure die foundry
Šromota, Michal ; Roučka, Jaromír (referee) ; Krutiš, Vladimír (advisor)
The master thesis, consisting of a theoretical and practical part, focuses on the issue of high pressure die casting, specifically the treatment of the die using micro spray technology. The goal of the thesis was to map the processes that need to be changed in the high pressure die casting foundry in order to successfully implement the use of micro-spraying. The practical part describes the introduction of micro spray technology in the foundry KOVOLIT Modřice a.s. In this case a transition from the conventional spraying method to the micro-spraying is made. After testing, both stable production and the expected savings associated with the operation of micro-spraying were achieved on the selected casting, and therefore it was decided to convert the production of the selected casting to this technology.
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Analysis of non-metalic inclusions in motor heads castings and suggestion on their remove
Dratnal, Lukáš ; Lána, Ivo (referee) ; Roučka, Jaromír (advisor)
Improving the quality of metal castings for serial production of automotive industry, leading to improvements in the properties of casts and their lower costs. This publication analyzes the non-metallic inclusions contained in casts of heads of internal combustion engines, molded of Nemak Czech Republic, Ltd. Tackling includes analysis of size, shape, chemical composition and hardness of the specific non-metallic inclusions. The thesis describes the purity metal holding furnaces and proposals to eliminate inclusions from metal.
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Low alloyed heat resistent iron
Král, Vojtěch ; Bouška, Ondřej (referee) ; Roučka, Jaromír (advisor)
While using iron casting behind temperatures above perhaps 500 oC namely especially at cyclic heat straining, happens to degradation of structure and to failure casts. To this goal certify cast iron with content Si plus Mo. Work set up survey types alloies, feature plus way of production of castings.
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Optimization of macrostructure of nickel-based alloys castings
Šmíd, Michal ; Ňuksa, Petr (referee) ; Roučka, Jaromír (advisor)
This diploma thesis is focusing on possibilities of influencing casting’s structure of nickel superalloy Inconel 713LC by force effects caused by vibration and rotation during crystallization. In this research were cast three test castings of turbine wheels with different solidification conditions that have affected the size and distribution of the grains. The aim was to compare the different microstructure and macrostructure of castings and then compare the dependence of grain refinement on mechanical properties. Changes in the structure were analyzed by means of light and electron microscopy methods after the fracture of test bars.
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