The design of the gating system and the adjustment of the technological parameters of high pressure die casting are closely correlated. Correct connection of the gating system structure and technological parameters will be reflected in the final casting quality. Significant influence on the filling progress of a mold cavity has a gate and its geometry. Within the gate, the final increasing of melt flow velocity arises and determines the filling mode. The contribution is devoted to the influence of the gate height on selected technological parameters. The obtained data are being evaluated and on the basis of the experimental results assessment, the recommendations applicable in the foundry industry are being deduced.
The issue of the quality of vocational education, school, teaching and learning of students should be in the interests of all participants in the education process. The quality of secondary school is the critical element in enhancing the attractiveness of vocational education in Slovakia. Finding an offcial scale that would provide such a information in Slovakia is unfortunately impossible. There is no system for evaluating the quality of vocational education and training (VET) at vocational schools. There are no clearly defined criterias, rules or any standards. Speaking of an assessing the level of quality of vocational education on the base of existing outcomes in formal education such as monitoring, final exams, graduation exams is resulting in one-sided evaluation and does not address the systematic coherence and complexivity of this issue. An essential step os to create a functional system of evaluation of VET in Slovakia. The article describes importance of VET which can play a central role in preparing young people for work, developing the skills of adults and responding to the labour market needs of the economy and presents the project Model of the quality evaluation of vocational education and training at secondary vocational schools in Slovakia that is currently ongoing on many secondary vocational schools in western Slovakia and Austria. The aim of the project is to develop and apply an open, flexible and adaptable quality management system. The article not only presents indicators for evaluation but also the way how can be evaluated each of them. The effort of this project is also to create specialized portal with support services that provide transparent, clear and specific information from this area of interest. The introduction of the evaluation framework, the selection of indicators that take established criteria into consideration and assembling of the scale is therefore more than relevant and require
One of the most important indicators of casting quality is porosity. The formation of pores is largely conditioned by the presence of hydrogen in the batch and subsequently in the melt. The gasification of the melt is the primary factor increasing the porosity of casts. This paper addresses the issue of reducing the melt gasification by using FDU (Foundry Degassing Unit) unit. The gas content in the melt is evaluated by determining the Dichte Index depending on the geometry and the degree of the FDU unit rotor wear. For experiments performed under the operating conditions, three types of graphite rotors with different geometries are used. The extent of melt gasification and the Dichte Index are monitored during the rotor wear, at a rate of 0%, 25%, 50%, 75% and 100% rotor wear. Secondly, the chemical composition of the melt is monitored depending on the design and wear of the rotor. It is proven that the design and the degree of rotor wear do not have significant effect on the chemical composition of the melt and all evaluated samples fell within the prescribed quality in accordance with EN 1706. With regard to the overall comparison of the geometry and wear of individual rotor types, it has been proven that, in terms of efficiency, the individual rotors are mutually equivalent and meet the requirements for melt degassing throughout the service life.
Polymeric materials are thanks its processing and utility properties materials in demand of common and special use. They are also largely replacing conventional materials. As the popularity of polymeric materials grows, also the amount of its waste increases. For this reason, there is introduced the term recycling as a method of processing, re-use of the waste, into technologies of polymeric processing. So, this paper deals with the possibilities of introduction of recycled material. The main part of this paper is created by an experiment that explores the changes of tensile properties of test specimen according to the selected percentage of additives in the volume of the basic granulate. The test specimen was produced by mixing pure granules with the addition of recycled and re-granulated materials. The conclusion of this work presents a comparison of the results of each tensile test that provide an overview of the behaviour and properties of the materials tested.
The proper design of the gating system including the tempering and venting of the mold significantly influences the final quality of the casting and economize the costs of the foundries. The initial numerical design of the gating system is often sufficient for creating of the documentation for the mold design, but without the practical experience of the designer, it does not reveal the hidden problem emerging from the melt flow through the gating system as well as the temperature and gas mode of the mold.The contribution is dedicated to the optimization of the runner dimensions determined by the numerical calculation. The theoretical part presents the methodology, based on which the gating system was designed for a particular type of the pressure casting. The experimental part is dedicated to the influence of the cross sectional area of the runner on the change of the melt temperature before entering the ingate. It was assumed that the larger runner cross section gives the melt greater volume and heat capacity and thus the melt enters the ingate with the higher temperature. The obtained temperature results are then compared witht he melt flow rate values, based on which an optimal sulotion for the runner design dimensions is determined.
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