Casting industry has been enriched with the processes of mechanization and automation in production. They offer both better working standards, faster and more accurate production, but also have begun to generate new opportunities for new foundry defects. This work discusses the disadvantages of processes that can occur, to a limited extend, in the technologies associated with mould assembly and during the initial stages of pouring. These defects will be described in detail in the further part of the paper and are mainly related to the quality of foundry cores, therefore the discussion of these issues will mainly concern core moulding sands. Four different types of moulding mixtures were used in the research, representing the most popular chemically bonded moulding sands used in foundry practise. The main focus of this article is the analysis of the influence of the binder type on mechanical and thermal deformation in moulding sands.
The results of testing the strength properties of experimental ceramic materials containing spending moulding sand after initial mechanical reclamation as a material for subsequent layers of the stucco composition were presented. Tests were carried out on spent moulding sands from various foundry technologies, i.e. sand with furfuryl resin and sand with hydrated sodium silicate. The spent, agglomerated moulding sand has undergone a crushing process. Next, the required granular fractions used for individual layers of the stucco material were separated. Ceramic samples, in which the spent moulding sand was a substitute for fresh silica sand in successive layers of the stucco composition, were prepared. As a reference material, identical ceramic samples were used but with all layers made from the fresh silica sand. Samples prepared in this way were used to determine the bending strength of ceramic materials in the temperature range from 20 to 900ºC. The obtained values of the bending strength have demonstrated that spent moulding sand can be used in investment casting with no adverse effect on the strength of ceramic materials.
W niniejszym artykule przedstawione zostały wybrane metody badań związane z powłokami ochronnymi stosowanymi na masy formierskie i rdzeniowe w odlewnictwie. Metodykę badawczą podzielono na badania właściwości technologicznych mas formierskich i rdzeniowych pokrytych powłokami (tj. parametr hot distortion po naniesieniu powłok na formy wykonane z sypkich mas samoutwardzalnych ze spoiwami organicznymi) i fizykochemicznych (lepkość) gotowych powłok. Do badań wykorzystano powłoki z rozpuszczalnikami wodnymi oraz alkoholowymi. Formy przygotowano z sypkich mas samoutwardzalnych z żywicą furfurylową oraz fenolowo-formaldehydową, które zostały pokryte wodną powłoką oraz powłoką alkoholową. Badania przeprowadzono w Katedrze Tworzyw Formierskich, Technologii Formy i Odlewnictwa Metali Nieżelaznych na Wydziale Odlewnictwa AGH w Krakowie oraz w Instytucie Odlewnictwa w Krakowie.
EN
This article presents selected research methods related to protective coatings used for sand moulds and cores in the foundry industry. The research methodology has been divided into studies of the technological properties of sand moulds and cores with applied coatings (the measurement of hot distortion parameter after deposition of coatings onto moulds made of loose self-hardening sands with organic binders) and physico-chemical properties (viscosity) of finished coatings. Coatings with aqueous and alcohol solvents were tested. Moulds were prepared from loose self-hardening sand mixtures with furfuryl and phenol-formaldehyde resins and were coated with water-based coatings and alcohol-based coatings. Studies were carried out in the Department of Moulding Materials, Mould Technology and Cast Non-Ferrous Metals at the AGH Faculty of Foundry Engineering in Krakow and at the Foundry Research Institute in Krakow.
The progressive mechanization and automation of industrial equipment is the driving force of progress, not only in the field of production but also in the measuring and control equipment. In mold production, the automation of processes such as forming molds and cores along with their assembly has led to increases in serial production, reductions in defects, and the shortening of molding times, among others. Thanks to automation in mold and core departments and the use of all sorts of manipulators, mold production in foundries has gained momentum. Unfortunately, in addition to the mentioned advantages, there are also new challenges as to the quality and properties of the molding and core sands used in highly automated foundries.This article presents recent research on molding sand elasticity. The topic was introduced as an attempt to answer the new needs of highly mechanized foundries. The article discusses a new method of measuring the resistance of molding materials to undergoing mechanical deformation (molding sand elasticity), with an additional analysis of the bending strengths of the tested samples. Precise measurements, test sample preparation, and interpretation of the received results are presented in the article.
The paper deals with squeeze casting technology. For this research a direct squeeze casting method has been chosen. The influence of process parameters variation (casting temperature, mold temperature, pressure) on mechanical properties and structure will be observed. The thicknesses of the individual walls were selected based on the use of preferred numbers and series of preferred numbers (STN ISO 17) with the sequence of 3.15, 4.00, 5.00, 6.00 and 8.00 mm. The width of each wall was 22 mm with a length of 100 mm. As an experimental material was chosen the AlSi12 and AlSi7Mg0.3 alloys. The mechanical properties (UTS, E) for individual casting parameters and their individual areas of different thicknesses were evaluated. In the structure the influence of pressure on the change of the eutectic morphology, the change of the volume of eutectic and the primary alpha phase, the effect of the pressure on the more fine-grain and the regularization of the structure were evaluated.
Blast furnace and cupola furnace are furnace aggregates used for pig iron and cast iron production. Both furnace aggregates work on very similar principles: they use coke as the fuel, charge goes from the top to down, the gases flow against it, etc. Their construction is very similar (cupola furnace is usually much smaller) and the structures of pig iron and cast iron are very similar too. Small differences between cast iron and pig iron are only in carbon and silicon content. The slags from blast furnace and cupola furnace are very similar in chemical composition, but blast furnace slag has a very widespread use in civil engineering, primarily in road construction, concrete and cement production, and in other industries, but the cupola furnace slag utilization is minimal. The contribution analyzes identical and different properties of both kinds of slags, and attempts to explain the differences in their uses. They are compared by the contribution of the blast furnace slag cooled in water and on air, and cupola furnace slag cooled on air and granulated in water. Their chemical composition, basicity, hydraulicity, melting temperature and surface were compared to explain the differences in their utilization.
The paper presents the results of an investigation of the thermal deformation of moulding sands with an inorganic (geopolymer) binder with a relaxation additive, whose main task is to reduce the final (residual) strength and improves knocking-out properties of moulding sand. The moulding sand without a relaxation additive was the reference point. The research was carried out using the hot-distortion method (DMA apparatus from Multiserw-Morek). The results were combined with linear deformation studies with determination of the linear expansion factor (Netzsch DIL 402C dilatometer). The study showed that the introduction of relaxation additive has a positive effect on the thermal stability of moulding sand by limiting the measured deformation value, in relation to the moulding sand without additive. In addition, a relaxation additive slightly changes the course of the dilatometric curve. Change in the linear dimension of the moulding sand sample with the relaxation additive differs by only 0.05%, in comparison to the moulding sand without additive.
The constantly developing and the broadly understood automation of production processes in foundry industry, creates both new working conditions - better working standards, faster and more accurate production - and new demands for previously used materials as well as opportunities to generate new foundry defects. Those high requirements create the need to develop further the existing elements of the casting production process. This work focuses on mechanical and thermal deformation of moulding sands prepared in hot-box technology. Moulding sands hardened in different time periods were tested immediately after hardening and after cooling. The obtained results showed that hardening time period in the range 30-120 sec does not influence the mechanical deformation of tested moulding sands significantly. Hot distortion tests proved that moulding sands prepared in hot-box technology can be characterized with stable thermal deformation up to the temperature of circa 320 °C.
Powłoki ochronne stosuje się w celu uzyskania odlewów o gładkiej powierzchni, bez wad. Powłoki ochronne mogą zawierać rozpuszczalnik na bazie wody lub alkoholu, jednak ze względu na szkodliwość zaleca się ograniczenie stosowania powłok alkoholowych. Sposób nanoszenia powłok na powierzchnię rdzenia lub formy zależy od wymagań i potrzeb wykonawcy. W niniejszym artykule zamieszczono wyniki badań, przedstawiające wpływ grubości powłoki ochronnej z różną zawartością rozcieńczalnika na wybrane właściwości mas. Badaniom poddano masy II generacji wiązane spoiwami organicznymi i nieorganicznymi. Określony został wpływ grubości powłoki na wytrzymałość na zginanie w funkcji wielkości odkształcenia. Kształtki poddano również badaniom parametru hot distortion. Dodatkowo wykonano zdjęcia mikroskopowe przedstawiające głębokość penetracji powłoki w głąb masy. Badania parametru hot distortion wykazały, że w zależności od rodzaju spoiwa zastosowanego w masie dodatek rozcieńczalnika do powłoki przynosi odmienne efekty.
EN
Protective coatings are applied in order to obtain casts with an even surface, without faults. Protective coatings can contain a solvent based on water or alcohol; however, due to their harmfulness, it is recommended to limit the use of alcohol coatings. The manner of applying the coatings onto the surface of a core or a mould depends on the requirements and needs of the executor. This article presents test results demonstrating the effect of the thickness of a protective coating, with different solvent contents, on selected properties of masses. The studies were performed on II generation masses bound with organic and inorganic binders. The effect of the coating’s thickness on the bending strength as a function of deformation degree was determined. The profiles were also tested in respect of the hot distortion parameter. Additionally, microscopic photos were taken showing the depth of the coating’s penetration towards the inside of the mass. The hot distortion parameter tests showed that, depending on the type of binder used in the mass, the addition of a diluent produces different results.
The results of own studies concerning the application of a new additive to the CO2-hardened sodium water glass foundry sands are presented. The new additive, which is a composition of aqueous solutions of modified polyalcohols, has been designated by the symbol “B” and is used as an agent improving the sand knocking out properties. The scope of studies included various mechanical and technological properties of foundry sand mixtures, such as permeability, friability, life cycle of cores and knocking out properties. Two types of water glass with different values of the silica modulus and density, designated as R145 and R150, were tested. Moulding sands used in the tests were made with the additive “B”. For comparison, a reference sand mixture with water glass but without the additive “B” was also prepared.
The subject of the study is the improvement of the quality of moulding sand preparation. An exploration research performed on the data concerning moulding sand quality parameters was described. The aim of the research was to find relationships between various factors determining the properties of moulding sands and, based on the results obtained, build models predicting the sand moisture content with the induction of classification and regression trees. A two-match prediction approach was demonstrated and its effectiveness in evaluating the moulding sand moisture content was discussed. The knowledge in the form of rules acquired in this way can be used in the creation of knowledge bases for systems supporting decisions in the diagnostics of the moulding sand rebonding process. Formalized knowledge also facilitates further processing of the measurement data.
Obciążenia cieplne, którym poddawane są formy i rdzenie, powodują termiczne zmęczenie materiału, które może generować tworzenie się wad takich jak: pęknięcia, wżarcia, żyłki, wykruszanie materiału formy podczas zalewania. Może dochodzić także do przypalenia i penetracji metalu do masy formierskiej lub rdzeniowej. Jednym z rozwiązań ograniczającym występowanie niekorzystnych zjawisk jest zastosowanie powłok ochronnych. Nanoszone są one w celu poprawy jakości powierzchni odlewów oraz ułatwienia wyjęcia odlewu z formy. W niniejszym artykule zaprezentowano wstępne wyniki badań wpływu zwiększonej ilości rozcieńczalnika w powłokach, na głębokość penetracji powłoki w głąb rdzeni oraz pomiar parametru hot distortion.
EN
Thermal loads applied to moulds and cores cause thermal fatigue and the appearance of flaws such as: cracks, penetration, veins, spalling of mould material during casting. Scorching and penetration of metal into the moulding sand or core sand are also possible. One of the solutions that limit the occurrence of unfavourable phenomena is using protective coatings. They are applied in order to improve the quality of castings and make it easier to extract a casting from the mould. This article presents a general classification of coatings applied to casting moulds and cores. It focusses mainly on protective coatings and describes the methods of applying and drying them. Preliminary results of coating tests are presented, including microscopic observation of the depth of coating penetration into mass and a measurement of the hot distortion parameter relative to the amount of solvent added.
The paper presents possibility of using biodegradable materials as parts of moulding sands’ binders based on commonly used in foundry practice resins. The authors focus on thermal destruction of binding materials and thermal deformation of moulding sands with tested materials. All the research is conducted for the biodegradable material and two typical resins separately. The point of the article is to show if tested materials are compatible from thermal destruction and thermal deformation points of view. It was proved that tested materials characterized with similar thermal destruction but thermal deformation of moulding sands with those binders was different.
Modern techniques of castings production, including moulding sands production, require a strict technological regime and high quality materials. In the case of self-hardening moulding sands with synthetic binders those requirements apply mainly to sand, which adds to more than 98% of the whole moulding sand mixture. The factors that affect the quality of the moulding sands are both chemical (SiO2, Fe2O3 and carbonates content) and physical. Among these factors somewhat less attention is paid to the granulometric composition of the sands. As a part of this study, the effect of sand quality on bending strength Rgu and thermal deformation of self-hardening moulding sands with furfural and alkyd resin was assessed. Moulding sands with furfural resin are known [1] to be the most susceptible to the sand quality. A negative effect on its properties has, among others, high content of clay binder and so-called subgrains (fraction smaller than 0,1mm), which can lead to neutralization of acidic hardeners (in the case of moulding sands with furfuryl resin) and also increase the specific surface, what forces greater amount of binding agents. The research used 5 different quartz sands originating from different sources and characterized with different grain composition and different clay binder content.
Współczesne odlewnictwo cechuje wysoki stopień automatyzacji w procesach produkcji masowej. Wspomaganie procesów zakładania rdzeni i składania form odlewniczych przez wszelkiego rodzaju manipulatory oraz roboty przyczynia się do pękania form oraz rdzeni podczas montażu. Często występujące uszkodzenia rdzeni są wynikiem niskiej elastyczności mas formierskich, nawet przy wysokiej wytrzymałości rdzeni. W celu zbadania tego zjawiska opracowany został specjalny moduł pomiarowy połączony z klasycznym pomiarem skłonności mas do odkształceń w wysokich temperaturach – hot distortion. W ramach niniejszej pracy przedstawiona zostanie szczegółowo metodyka pomiaru oraz wstępne badania elastyczności i deformacji cieplnej dla sypkich mas samoutwardzalnych ze spoiwem furfurylowym oraz alkidowym o określonych składach.
EN
Modern casting is characterized by a high degree of automation in the processes of mass production. Supporting the processes of inserting cores and composing the moulds with all kinds of manipulators and robots leads to breakage of both cores and moulds during installation. Common core damages are the result of low elasticity of the moulding sands, despite high strength resistance of the cores. In order to investigate this phenomenon a special measuring module, connected with a classical measurement of the tendency of moulding sands to deform in high temperatures-hot distortion, has been developed. Within the framework of this paper the methods of measurement and preliminary research of elasticity and thermal deformation of self-hardening moulding sands with furfuryl and alkyd binders will be presented.
The necessity of receiving high quality castings forces undertaking research to elaborate moulding and core sands ensuring obtaining the materials with relevant technological parameters and also with high environmental standards. The most important group here are moulding sands with hydrated sodium silicate. Unfortunately, their fundamental disadvantages are weak knock-out properties. The article presents the most commonly used methods of measuring the knock-out properties of moulding and core sands. The authors propose a new method for estimation this parameter. The method is based on the measurement of high-temperature expansion.
PL
Potrzeba uzyskiwania wysokiej jakości odlewów wymusza podejmowanie prac badawczych dla otrzymania mas formierskich i rdzeniowych zapewniających uzyskanie tworzyw o odpowiednich parametrach technologicznych, jednocześnie spełniających wysokie wymogi ochrony środowiska. Najważniejszą grupę stanowią tutaj masy z uwodnionym krzemianem sodu. Niestety jedną z ich podstawowych wad jest słaba wybijalność. W artykule zostały przedstawione najczęściej stosowane metody pomiaru wybijalności mas formierskich i rdzeniowych Autorzy zaproponowali nową metodę oceny wybijalności opierającą się na pomiarze ekspansji wysokotemperaturowej.
The article discusses the issue of the influence of furfuryl alcohol content in resin binders on properties of moulding sand at elevated temperature. Reducing the share of this component - due to the requirements of the European Union regarding its toxicity - may cause a decrease in temperature of moulding sands’ destruction and, consequently, the thermal deformation of moulds and the creation of many casting defects. The study examined the impact of the furfuryl alcohol content of the thermal destruction processes and on the strength of the moulding sand at an ambient temperature and the tendency to thermal deformation.
PL
W artykule omówiono zagadnienie wpływu zawartości alkoholu furfurylowego w spoiwach żywicznych na właściwości mas formierskich w podwyższonej temperaturze. Zmniejszenie udziału tego składnika – spowodowane wymaganiami Unii Europejskiej odnośnie jego toksyczności – może powodować obniżenie temperatur destrukcji masy, a w konsekwencji deformację cieplną form i powstanie wielu wad odlewniczych. W pracy przebadano wpływ zawartości alkoholu furfurylowego na procesy cieplnej destrukcji spoiwa a także na wytrzymałość masy w temperaturze otoczenia oraz skłonność do deformacji cieplnej.
Technological knowledge is a collection of information from each stage of the casting production preparation process along with production data and quality control data. Knowledge and experience are the most important factors for the dynamic development of each foundry. Efficient archiving and management of technological knowledge, including computer simulations, is a critical part of building competitive advantage. Analysis of historical data allows for drawing the right conclusions, and guarantees improved quality of the final product. Effective enterprise management system, and technological knowledge management system in particular, is an indispensable tool for any innovative foundry. Simulation Process & Data Management is a new, dynamically-developing scientific field. Also in the foundry industry it is a very important step towards the management of casting simulation results.
PL
Wiedza technologiczna jest to zbiór informacji pochodzących z każdego etapu przygotowania produkcji odlewniczej. Wiedza, doświadczenie są najważniejszym czynnikami dynamicznego rozwoju każdej odlewni. Umiejętne archiwizowanie i zarządzanie wiedza technologiczna, w tym symulacjami komputerowymi jest kluczowym elementem budowania przewagi konkurencyjnej. Analiza danych historycznych umożliwia wyciąganie właściwych wniosków oraz gwarantuje poprawe jakości wyrobu końcowego. Efektywny system zarządzania przedsiebiorstwem, w szczególności system zarządzania wiedzą technologiczną jest niezbędnym narzędziem każdej innowacyjnej odlewni. Simulation Process & Data Management jest nową, dynamicznie rozwijającą się dziedzina nauki. W branży odlewniczej jest to bardzo ważny krok w kierunku zarządzania wynikami symulacji dla odlewnictwa.
Application of modern technological solutions, as well as the economic and ecological solutions, is for foundries one of the main aspects of the competitiveness on the market for castings. IT solutions can significantly support technological processes. This article presents neural networks with different structures that have been used to determine the moisture content of the moulding sand based on the moulding sand selected properties research results. Neural networks were built using Matlab software. Moulding sand properties chosen for quality control processes were selected based on wide previous results. For the proposed moulding sand properties, neural networks can be a useful tool for predicting moisture content. The structure of artificial neural network do not have a significant influence on the obtained results. In subsequent studies on the use of neural networks as an application to support the green moulding sand rebonding process, it must be determined how factors such as environmental humidity and moulding sand temperature will affect the accuracy of data obtained with the use of artificial neural networks.
PL
Zastosowanie nowoczesnych rozwiązań technologicznych, a także ekonomicznych i ekologicznych stanowi dla odlewni jeden z głównych aspektów konkurencyjności na rynku produktów odlewów. Doskonałym wsparciem dla procesów technologicznych są rozwiązania informatyczne. W artykule zaprezentowano sieci neuronowych o różnej strukturze, które zostały użyte do określania wilgotności masy formierskiej na podstawie wyników badania wybranych właściwości masy. Sieci neuronowe zbudowano z wykorzystaniem oprogramowania Matlab. Właściwości mas wybrane do procesów sterowania jakością zostały dobrane w oparciu o wcześniejsze wyniki badań. Dla zaproponowanych właściwości syntetycznych mas formierskich sztuczne sieci neuronowe mogą być użytecznym narzędziem do przewidywania wilgotności masy. Ilość warstw ukrytych w strukturze sieci nie ma wpływu na otrzymywane rezultaty. W kolejnych badaniach nad wykorzystaniem sieci neuronowych jako aplikacji wspierającej procesy odświeżania syntetycznych mas formierskich, należy okreslić, w jaki sposób czynniki takie jak wilgotność otoczenia, czy temperatura masy wpłyną na dokładność danych uzyskanych z wykorzystaniem sztucznych sieci neuronowych.
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