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1

Utilizing of the Statistical Analysis for Evaluation of the Properties of Green Sand Mould

Abdulamer Dheya

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 3

67--73

EN

A statistical approach was conducted to investigate effect of independent factors of the mixing time compactability and bentonite percentage on dependent variables of permeability, compression and tensile strength of sand mould properties. Using statistical method save time in estimating the dependent variables that affect the moulding properties of green sand and the optimal levels of each factor that produce the desired results. The results yielded indicate that there are variations in the effects of these factors and their interactions on different properties of green sand. The outcomes obtained a range of permeability values, with the highest and lowest numbers being 125 and 84. The sand exhibited high values of tensile and compressive strength measuring at 0.33N/cm2 and 17.67N/cm2 . Conversely it demonstrated low levels of tensile and compressive strength reaching 0.14N/cm2 and 9.32N/cm2 . These results suggest that the moulding factors and their interactions have an important role in determining properties of the green sand. ANOVA was used to assess effect of various factors on different properties of the green sand. The results obtained suggest that compactability factor play a significant effect on permeability, the mixing time or bentonite factor has a significant effect on the compressive strength and mixing time or compactability factor has a significant impact on the tensile strength with a significance level lower than 5%. It is found that neither the mixing time nor the amount of bentonite used in the green sand mix has a significant impact on its permeability. Compactability of the green sand does not has a significant effect on the compressive strength. Bentonite used in green sand mix does not have a significant impact on its tensile strength.

2

Impact of the Different Moulding Parameters on Properties of the Green Sand Mould

Abdulamer Dheya

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 2

5--9

EN

Sand Casting process depends mainly on properties of the green sand mould, sand casting requires producing green sand mould without failure and breakage during separation the mould from the model, transportation and handling. Production of the green sand mould corresponding to dimensions and form of the desired model without troubles depends on the properties of the green sand. Ratio of constituents, preparation method of the green sand, mixing and pressing processes determine properties of green sand. In the present work, study effect of the moulding parameters of bentonite content, mixing time, and compactability percentage on the properties of the green sand mould have been investigated. Design of experiments through Taguchi method was used to evaluate properties of permeability, compressive strength, and tensile strength of the green sand. It was found that 47% of compactability, 9(min) of mixing time, and 6% of bentonite content gives highest values of these properties simultaneously.

3

Evaluation of Mixing Efficiency and How it Affects the Properties of the New Green Sand Mixtures

Kielar Šimon, Bašistová Martina, Lichý Petr

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 3

88--93

EN

The current trend in the preparation of green sand mixtures emphasizes the acceleration of the mixing process while maintaining the quality of the mixture. This requirement results in the necessity of determining the optimal conditions for mixing the mixture with a given mixer. This work aims to determine the optimal mixing conditions for the newly introduced eddy mixer LM-3e from the company Multiserw-Morek in the sand laboratory at the Department of Metallurgical Technologies, Faculty of Materials and Technology, VŠB - Technical University of Ostrava. The main monitored properties of mixtures will be green compressive strength and moisture of the mixture. The measured properties of the mixture mixed on the eddy mixer will be compared with the properties of the mixture mixed on the existing LM-2e wheel mixer. The result of the experiment confirmed that the eddy mixer is suitable for the preparation of a mixture of the same quality as the wheel mixer but with a significantly reduced mixing time.

4

The Optimization of a Numerical Steel Foundry Simulation Through a Characterization of the Thermal Properties of the Materials

Souêtre Morgan, Vaucheret Alexis, Jacquet Philippe, Carton Jean-François

Journal of Casting & Materials Engineering

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2022

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Vol. 6, no. 4

76--80

EN

In many foundries, numerical simulation is used to determine the origins of different defects as this tool allows the acceleration of the design process. However, the databases provided by different software do not seem to tally with the actual properties of the material. In fact, every foundry uses a different grade of steel and varying mixtures of sand. An evaluation of the impact of different material properties showed the importance of measuring every physical property to improve the database of the software. Following this, an experiment was conducted to evaluate the gap between numerical simulations and the results obtained through experimentation. This experiment, called thermal analysis, consists in measuring the solidification and cooling of a cylinder filled with liquid steel. After the calculation of the steel properties and a simulation with real experimental parameters, a comparison between each cooling curve was realized. This comparison shows that the calculated properties provide a simulated cooling curve which is closer to the experimental curve than the properties in the original database. We did not explore all of the metal properties in this study, but the modification of the sand properties was explored, together with the thermal conductivity of the steel and sand. These other measurements will be obtained in a future study.

5

Detection of nitrates(V) and sulfates(VI) by UV-Vis spectrophotometry method in used green sand bonded by bentonite with modified starch addition

Grabowska B., Kurleto-Kozioł Ż., Szymański Ł., Kaczmarska K., Bobrowski A.

Metallurgy and Foundry Engineering

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2016

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Vol. 42, no. 4

203--211

EN

The research results (SEM, UV-Vis) that contain a part of the work connected with determining the influence of a modified starch addition on the physical and chemical property changes of green sands (including the emission levels of harmful substances from the used molding sands formed as a result of the liquid metal pouring of molds) are presented in this paper. A surface analysis (SEM) was performed for the fresh molding sands and used molding sands with and without modified starch samples. On the bases of the received microscopic images, the impact of the temperature factor on the morphology of the molding sand samples after the liquid metal pouring process are assessed. In the second part of the performed work on the UV-Vis research, eluates from two used molding sands (green sand [sand number 1] and green sand with the addition of a modified starch [sand number 2]) were tested for nitrate and sulfate content. In order to determine whether the level of nitrate and sulfate elusion from the used molding sands is permissible, the received results were compared with the Minister of Environment’s regulations concerning the requirements of surface waters used for supplying the population with potable water.

PL

W artykule przedstawiono wyniki badań (SEM, UV-Vis), wchodzących w zakres prac związanych z określeniem wpływu dodatku modyfikatu skrobiowego na zmianę właściwości fizycznych i chemicznych mas wiązanych bentonitem, w tym na poziom wydzielania substancji szkodliwych ze zużytych mas powstałych w procesie zalewania formy ciekłym metalem. Analizę powierzchniową (SEM) przeprowadzono dla próbek klasycznych mas świeżych i zużytych bez dodatku i z dodatkiem modyfikatu skrobiowego. Na podstawie otrzymanych zdjęć mikroskopowych oceniono wpływ czynnika temperatury na morfologię próbek masy po procesie zalewania formy ciekłym metalem. W drugiej części wykonanych prac badaniom UV-Vis na zawartość azotanów(V) i siarczanów( VI) poddano eluaty przygotowane z udziałem dwóch mas zużytych, tj.: klasycznej masy formierskiej (masa I) oraz klasycznej masy formierskiej z dodatkiem modyfikatu skrobiowego (masa II). W celu określenia poziomu wymywalności azotanów(V) i siarczanów(VI) ze zużytych mas otrzymane wyniki porównano z obowiązującym Rozporządzeniem Ministra Środowiska z dnia 27 listopada 2002 r. w sprawie wymagań, jakim powinny odpowiadać wody powierzchniowe wykorzystywane do zaopatrzenia ludności w wodę przeznaczoną do spożycia.

6

Kryteria oceny właściwości wiążących bentonitów

Żymankowska-Kumon S.

Archives of Foundry Engineering

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2012

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Vol. 12, iss. 1s

209--213

PL

W artykule zaproponowano kryteria jakimi należy się kierować przy ocenie właściwości wiążących bentonitów stosowanych do mas formierskich. Poza standardowym parametrem jakim jest zawartość aktywnego bentonitu należy uwzględnić wskaźnik swobodnego pęcznienia, który wydaje się być bardziej adekwatny w ocenie wytrzymałości masy na ściskanie. Przeprowadzone badania dla trzech rodzajów bentonitów stosowanych w polskich odlewniach, poddanych działaniu wysokiej temperatury wykazały, że przebieg zmian wskaźnika swobodnego pęcznienia jest bardzo zbliżony do przebiegu zmian wytrzymałości masy na ściskanie. Natomiast charakter zmian zawartości montmorillonitu w masie w zależności od temperatury jest odmienny. Pomimo tego, że masa wykazuje znaczną zawartość aktywnego bentonitu, jej wytrzymałość na ściskanie spada bardzo gwałtownie. Zawartość montmorillonitu w próbkach bentonitów oznaczono nowoczesną metodą kompleksu miedziowego – trietylenotetraaminy (Cu(II)-TET). Badania prowadzono dla bentonitów i mas z tymi bentonitami poddawanych działaniu wysokiej temperatury w zakresie 100-700ºC.

EN

The criteria, with which one should be guided at the assessment of the binding properties of bentonites used for moulding sands, are proposed in the paper. Apart from the standard parameter which is the active bentonite content, the unrestrained growth indicator should be taken into account since it seems to be more adequate in the estimation of the sand compression strength. The investigations performed for three kinds of bentonites, applied in the Polish foundry plants, subjected to a high temperature influences indicate, that the pathway of changes of the unrestrained growth indicator is very similar to the pathway of changes of the sand compression strength. Instead, the character of changes of the montmorillonite content in the sand in dependence of the temperature is quite different. The sand exhibits the significant active bentonite content, and the sand compression strength decreases rapidly. The montmorillonite content in bentonite samples was determined by the modern copper complex method of – triethylenetetraamine (Cu(II)-TET). Tests were performed for bentonites and for sands with those bentonites subjected to high temperatures influences in a range: 100-700ºC.

7

Determination of the overheating degree of moulding sand with bentonite - on the grounds of simulation investigations

Żymankowska-Kumon S., Holtzer M., Lelito J., Dańko R.

Archives of Foundry Engineering

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2012

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Vol. 12, iss. 4

176-180

EN

A determination of the heating degree of the moulding sand with bentonite on the grounds of simulating investigations with the application of the MAGMA program, constitutes the contents of the paper. To this end the numerical simulation of the temperature distribution in the virtual casting mould was performed. It was assumed that the mould cavity was filled with a moulding sand with bentonite of a moisture content 3,2 % and bentonite content 8%. A computer simulation can be used for predicting the heating degree of moulding sands with bentonite. Thus, prediction of the active bentonite (montmorillonite) content in individual layers of the overheated moulding sand can be done by means of the simulation. An overheating degree of a moulding sand with bentonite, and thus the bentonite deactivation depends on a temperature of a casting alloy, casting mass, ratio of: masssand : masscasting, moulding sand amount in the mould and contact area: metal - mould (geometry of the casting shape). Generally it can be stated, that the bentonite deactivation degree depends on two main factors: temperature of moulding sand heating and time of its operation.

8

Influence of moulding sands grain size on the effectiveness of quality control systems

Jakubski J., Dobosz S. M., Major-Gabryś K.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 2

47-50

EN

One of the modern methods of the production optimisation are artificial neural networks. Neural networks owe their popularity to the fact that they constitute convenient tools, which can be applied in an extremely broad research scope. This is caused by their ability to represent complex functions. Their non-linearity should be specially emphasised. Neural networks are gaining broader and broader application in the foundry industry, among others for controlling melting processes in cupolas and in arc furnaces, for designing castings and supply systems, for controlling moulding sand processing, for predicting properties of cast alloys or selecting parameters of pressure castings. An attempt to apply neural networks for controlling the quality of bentonite moulding sands is presented in this paper. This is the assessment method of sands suitability by means of detecting correlations between their individual parameters. The presented investigations were obtained by using the Statistica 9.0 program. The aim of the investigations was to select the neural network suitable for prediction the moulding sand moisture on the basis of the determined sand properties such as: permeability, compactibility, friability and compressive strength in dependence on the matrix grain size.

9

Selected parameters of moulding sands for designing quality control systems

Jakubski J., Dobosz S. M.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 3

11--16

EN

One of the modern methods of production optimisation are artificial neural networks. Neural networks owe their popularity to the fact that they are convenient tools, which can be utilised in a wide scope of problems. They are capable of reflecting complex functions. Especially their non-linearity should be emphasised. They are gaining wider and wider application in the foundry industry, among others, to control melting processes in cupolas and arc furnaces, designing castings and supply systems, control of moulding sands treatments, prediction of properties of cast alloys as well as selecting die casting. An attempt of the application neural networks to the quality control of moulding sands with bentonite is presented in the paper. This is a method of assessing the suitability of moulding sands by finding correlations in between individual parameters, by means of artificial neural network systems. The presented investigations were performed with the application of the Statistica 8.0 program. The investigations were aimed at the selection of the proper kind of a neural network for prediction a sand moistness on the bases of certain moulding sand properties such as: permeability, compactibility and friability. These parameters – determined as sand moistness functions - were introduced as initial parameters. Application of the Statistica program allowed for an automatic selection of the most suitable network for the reflection of dependencies and interactions existing among the proposed parameters. The best results were obtained for unidirectional multi-layer perception network (MLP). The neural network sensitivity to individual moulding sand parameters was determined, which allowed to reject not important parameters when constructing the network.

10

Reclamation of material from used ceramic moulds applied in the investment casting technology

Holtzer M., Zych J., Dańko R., Bobrowski A.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 3

199--204

EN

Investigations on utilisation of reclaimed materials from used ceramic moulds applied in the investment casting technology, are presented in the hereby paper. This reclaim was used as a matrix for the preparation of the test moulds. Rheological properties as well as tensile strength at a room temperature of such ceramic sands were even better than of sands made of fresh components. However, ceramic sands with a reclaimed material exhibited worse properties at higher temperatures. The second direction of utilizing the reclaim was using it as the so-called powder topping when making ceramic moulds (for the IInd and successive layers). Tensile strength values at high temperatures of moulds made with the reclaim participation were comparable (and in some cases even higher) to values of moulds made of fresh components (Al2O3). These results encourage the further investigations in this field.

11

Rebounding process of moulding sands-thermal degradation of bentonite binding qualities

Dańko R.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 1 spec.

233--236

EN

Problems related to a gradual degradation of binding qualities of montmorillonite, the main component of foundry bentonites, are presented in the paper. This degradation is caused by high temperatures originated from liquid metal influencing moulding sands. Laboratory measurements of an active binding agent content in classic moulding sands prepared with two types of bentonite and subjected to a controlled heating to high temperatures – were performed. These laboratory examinations were compared to industrial tests, in which a temperature distribution was being determined in several places in the thickness of the casting ingot mould for 24 hours from the moment of pouring liquid metal. On the basis of the performed examinations, the method allowing to determine optimal additions in the rebounding process of the tested bentonites was developed.

12

Investigation of carriers of lustrous carbon at high temperatures

Holtzer M., Bobrowski A., Grabowska B., Schindler A., Hodor K.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 1 spec.

225--232

EN

Lustrous carbon is very important in processes of iron casting in green sand. Lustrous carbon (pirografit) is a microcrystalline carbon form, which evolves from a gaseous phase. In the case of applying additions, generating lustrous carbon, for sands with bentonite, there is always a danger of emitting – due to a high temperature of liquid cast iron and a humidity-compounds hazardous for a human health. There can be: CO, SO2, benzene, toluene, ethylbenzene, xylene (the so-called: BTEX) as well as polycyclic aromatic hydrocarbons (PAHs). In order to asses the selected mixtures: bentonite – carrier of lustrous carbon, in which a coal dust fraction was limited, the thermogravimetric analysis and the analysis of evolving gases were performed. Examinations were carried out in the Applications Laboratory NITZSCH-Gerätebau GmbH, Selb/Bavaria, Germany. The NETZSCH model STA 449 F3 Jupiter® simultaneous thermal analyzer was used to measure the mass change and transformation energetics of materials. The system employed for this work was equipped with an SiC furnace capable of operation from 25 to 1550 °C. The mass spectrometer of the QMS 403 allows detection of mass numbers between 1 and 300 amu (atomic mass unit).

13

Assessment of harmfulness of green sand with additions of dust from dry dedusting

Holtzer M., Bobrowski A.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 3

193--198

EN

Recently, in the literature about the problems cause to the environment by foundry industry, attention has been paid to the presence and harmful effect of aromatic hydrocarbons: benzene, toluene, ethylbenzene and isomers of xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAHs). The growing interest in these pollutants of the environment is a result of their biological activity; some of them are characterized by mutagenic and carcinogenic action. In foundries these hydrocarbons are emitted during the contact between mould or core sands and liquid metal. This article discusses the results of the studies made on the elution rate of some harmful compounds include polycyclic aromatic hydrocarbons (PAHs) (Table 3 and 4) from waste mould sand with bentonite and coal dust M1 (mixture Kormix 75) and this one with addition of dust from dry dedusting of sand M2 preparing station (partial replacement of bentonite) and emission of BTEX gases from this moulds poured with molten cast iron. From the results given in these tables it follows that both mould sands are characterized by low values of the concentration of investigation substances and haven’t negative influence for environment during casting or management in other means. Tests were done according to the methodology developed at Faculty of Foundry Engineering University of Science and Technology in Cracow.

14

Assessment of environmental influence of bentonite and lustrous carbon carrier - in an aspect of gases emission

Bobrowski A., Holtzer M.

Archives of Foundry Engineering

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2009

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Vol. 9, iss. 1

21-24

EN

The emission results of the selected gases from a bentonite-carbon mixture and from dusts originated from dry de-dusting of the green sand processing plant (at high temperatures) are presented in the paper. In order to check and compare samples of dusts and bentonite-carbon mixtures in respect of emission of gases the Evolved Gas Analysis (EGA) was performed by means of the mass spectrometry method. This method allows to determine emission conditions of the selected chemical compounds.

15

Zastosowanie pyłu krzemionkowego do produkcji form odlewniczych

Holtzer M., Drożyński D., Koza T.

Archiwum Odlewnictwa

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2006

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R. 6, nr 18/2

385--392

PL

W artykule przedstawiono wyniki badań wpływu dodatku pyłu krzemionkowego, powstającego przy produkcji żelazostopów na właściwości technologiczne klasycznych mas formierskich. Jako masę wyjściową zastosowano masę z bentonitem na osnowie piasku kwarcowego. Przeprowadzono szereg prób mas z różną zawartością pyłu krzemionkowego. W badanych masach wykonano różne odlewy żeliwne i staliwne, które charakteryzowały się wymaganymi właściwościami i posiadały odpowiednią jakość powierzchni.

EN

This paper deals with industrial tests carried out to determine influence of silica powder contents on selected properties of green sand. The addition of silica powder was as a way leading to some replacement. During the tests the sand mould prepared with addition of determined amount of silica powder were poured using both cast iron as well as cast steel. Obtained castings had a good surface and quality.

16

Modern bentonite bonded molds

Grefhorst C.

Archiwum Odlewnictwa

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2006

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R. 6, nr 20

51--57

EN

In scope of global competition, foundries must optimise their production to get higher efficiency and less casting defects. At the same time, legislation and community demand reduction of emissions, healthier working conditions and less foundry waste, less burdened with organic pollutions. To achieve this, an optimisation of bentonite-bonded moulding sand is required. Through the use of high standard bentonites and carbonaceous additives moulding performance can be increased and consumption can be decreased. In consequence, this reduces emissions and waste volume.

PL

Większość odlewów żeliwnych produkowanych w UE jest wykonywana w formach z mas z bentonitem zawierających pył węglowy lub dodatki organiczne. Zużycie dodatków nawęglających w odlewniach europejskich wynosi rocznie około 90.000 t. Wszystkie stosowane aktualnie materiały zawierające węgiel emitują po zalaniu niebezpieczne substancje. Odpowiednia selekcja i stosowanie dodatków zawierających mniej substancji lotnych może znacznie ograniczyć tę emisję.

17

Reusing of dust collector material as a green sand additive

Bednářová V., Mikšovský F.

Archiwum Odlewnictwa

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2004

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R. 4, nr 13

13--18

EN

Possibilities of reusing materials from dry and wet dust collector systems to the green moulding sand. Results of dusts testing active bentonite, pH, lustrous carbon, sieve analysis, fines, hazardous components i.e. Reusing of dust as a green moulding sand additive – laboratory testing and pilot plant experiences – technological properties of such moulding sand and the quality of produced castings.

PL

W artykule opisano badania dotyczące możliwości wykorzystania pyłów pochodzących z odpylania stanowisk sporządzania mas, wykonywania form i wybijania odlewów. Pyły te w składzie mają bentonit i dodatki substancji zawierających węgiel. Pyły zostały wykorzystane do sporządzania mas z bentonitem. Wykonane, w formach sporządzonych z tych mas, odlewy posiadały dobrą powierzchnię. Próby przeprowadzono dla odlewów żeliwnych o grubości ścianek 10, 20 i 30 mm.

18

Wpływ dodatku pyłu krzemionkowego na właściwości klasycznych mas formierskich

Holtzer M., Rygulski T., Wyrobek A., Drożyński D.

Archiwum Odlewnictwa

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2003

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R. 3, nr 9

197--202

PL

W artykule przedstawiono wyniki badań wpływu dodatku pyłu krzemionkowego, powstającego przy produkcji żelazostopów, do klasycznych mas formierskich na ich właściwości technologiczne. Badania te stanowią element szerszych badań dotyczących możliwości wykorzystania pyłu krzemionkowego w odlewnictwie. Przeprowadzono próby z dodatkiem 2,5 i 5% pyłu. Jako masę wyjściową zastosowano masę z bentonitem na osnowie piasku kwarcowego. Ogólnie dodatek pyłu krzemionkowego powoduje przesunięcie uzyskiwania maksymalnych wartości przepuszczalności i wytrzymałości masy na rozciąganie i ściskanie w kierunku większych zawartości wody w masie. Wprowadzenie pyłu krzemionkowego ma korzystny wpływ na osiągane wartości wytrzymałości masy, zwłaszcza w przypadku wytrzymałości na rozciąganie. Jako optymalny dodatek do masy klasycznej uznano 5% pyłu.

EN

This papers deals with laboratory tests carried out to determine influence of silica powder contents on selected properties of green sand. The additions of silica powder were 2,5% and 5% as a sand replacement. The advantageous influence of silica powder on green sand compression and tensile strength and permeability was found. The optimum addition of silica powder was 5%.