This diploma thesis deals with the optimization of gating systems of shape-complex aluminum castings produced by investment casting process. Two castings whose massive gating systems make problem with the use of liquid metal (so called yield) were chosen for optimization. Each casting is described in its own chapter. The individual subchapters deal with description of the original and newly designed gating system. Simulation, test castings, X-ray inspection and metallographic examination were performed for each variant. At the end of each chapter there is an evaluation of the results of the optimization of gating system.

Production of top quality castings for applications in energy, aerospace and medical industries by the addition of ceramic cores to investment casting presents many metallurgical and technological problems. Ceramic cores applied in investment casting are subjects to many requirements in terms of their inertness to the casted alloy and at the same time to their final removal from the casting cavity in such a way that does not damage the casting. Both of these assumptions can be achieved by applying a thin layer of inert oxide ceramic coating to the surface of a ceramic core, made out of a chemically removable – leachable oxide ceramic.

The aim of this paper is to compare a bottom filling of a ceramic form made by lost wax process and a top filling conventional method. A computer simulation of filling and casting solidification will contribute to this comparison. The comparison includes evaluation of readings DAS and characteristic readings of porosity with chosen varieties of casting. The results show that the readings DAS did not change much but characteristic readings of porosity were much better at bottom filling. The computer simulation also showed a certain contribution in the field of model smelting technology.

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.

The introduction part of the thesis focuses on the overview of rapid prototyping in foundry industry. Principles of the most important RP methods are described and the FDM method is analyzed in more detail. This method was used in the practical part for the production of wax patterns with silicone moulds. The wax patterns were used for the production of castings using the lost wax method. The result of this work is determination of dimensional changes during the whole process of casting manufacture from the drawing to the final casting.

This diploma thesis is concerned with improving the mechanical properties of aluminium castings produced using investment casting technology by HIP (Hot Isostatic Pressing). Comparing the mechanical properties of separately casted test bars and integrally casted test bars for individual types of production. It was demonstrated that HIP technology has a positive effect on mechanical properties of castings, especially for ductility.

The main topic of the diploma thesis is simulation of the process when wax is filling the cavity of the "mother" metal die.This knowledge is the neccessary presumption for correct design of the gating system and setting correct injection parameters (temperature, pressure, wax flow) when making wax patterns.

Diploma thesis is focused to the optimization of the ceramic shell for pouring thin walled aluminium castings by investment casting technology. The main objective is firstly to find the optimal binding system (ceramic slurry) and stucco materials for the shell and secondly its optimal structure and heat treatment (drying of each coat and final shell firing) before metal pouring.

The topic of this thesis is the formation of microporosity in cast test bars of nickel-base superalloy Inconel 713LC during solidification. The theoretical part consists of nickel alloys, their macrostructure, the method of casting and crystallization of nickel-based superalloys. The second part is devoted to the design of casting conditions, the production of shell molds, the size and shape of grains, evaluation of microporosity by various available methods, comparing the influence of grain size and the proportion of microporosity on the resulting values of the mechanical tests. Experiments were carried out in cooperation with PBS Velká Bíteš and ÚST foundry department.

The thesis continue thematically in the previous development of the wax mixtures for the company Fimes. The general description of the investment casting process from the production of the die to casting of the wax pattern is handled in the first part. It is followed by the summary of the previously carried out experiments on cracking the shells. The experimental part describes the individual operations from the production of tested wax patterns to casting in the Boilercláv. The newly developed wax mixture is compared to the wax mixture used by the company Fimes. The experiments focus on the possibility of cracking the shells during the casting process and the dimensional stability of wax mixtures.