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1

The Use of 3D Printed Sand Molds and Cores in the Castings Production

Halejcio Dawid, Major-Gabryś Katarzyna

Archives of Foundry Engineering

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2024

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Vol. 24, iss. 1

32--39

EN

As a part of this work, an analysis of the current state of knowledge regarding the use of additive technology - binder jetting in the production of castings was made. The binder jetting (so-called 3D printing) has become the leading method of sand mold and core production. Within this paper types of molding and core sands with organic and inorganic binders that are and can be used in technology were analyzed. The need to carry out works aimed at developing pro-ecological molding / core sands with inorganic binders and organic binders with reduced harmfulness to the environment dedicated to binder jetting technology was noticed. The influence of technology parameters on the properties of molding / core sands and the properties of cast components was analyzed. It was shown that thanks to the unlimited shapes of the systems obtained with the use of additive technologies, it is possible to influence the rate of heat dissipation through the mold, which positively effects the process of solidification and crystallization of the castings.

2

The Influence of Silica Sand Granulometry and Sorting Level on Thermal Expansion

Bašistová Martina, Lichý Petr

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 3

12--15

EN

The quality of the castings depends, among other influences, on the quality of the moulding mixture used. The silica sands used are characterized by high thermal expansion compared to other sands. The tendency to dilatation of the moulding mixture can be influenced by the choice of the granulometric composition of the basic sand and the grain size. The aim of this work is to present the influence of grain distribution of foundry silica sand BG 21 from Biala Góra (Poland) and the degree of sorting (unsorted, monofraction, polyfraction) on the degree of thermal dilatation of the sand and thus on the resulting quality of the casting and susceptibility to foundry defects. For the purpose of measuring thermal dilatation, clay wash analysis was performed, sieve analysis of the sand was carried out, and individual sand fractions were carefully sorted. The measurements confirmed a higher thermal expansion in the case of monofractional sand grading, up to 51.8 %. Therefore, a higher risk of foundry stress-strain defects, such as veining, can be assumed.

3

The Influence of Biomaterial in a Binder Composition on Biodegradation of Waste from Furan Moulding Sands

Major-Gabryś Katarzyna, Stachurek I., Hosadyna-Kondracka M.

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 2

17--24

EN

Due to the observed increase in the amount of waste in landfills, there has been an increase in the demand for products made of biomaterials and the composition of biomaterials with petroleum-derived materials. The problem of waste disposal/management also applies to waste from the casting production process with the use of disposable casting moulds made with the use of organic binders (resins), as well as residues from the process of regeneration of moulding sands. A perspective solution is to add a biodegradable component to the moulding/core sand. The authors proposed the use of polycaprolactone (PCL), a polymer from the group of aliphatic polyesters, as an additive to a casting resin commonly used in practice. As part of this study, the effect of PCL addition on the (bio) degradation of dust obtained after the process of mechanical regeneration of moulding sands with organic binders was determined. The (bio) degradation process was studied in the environment reflecting the actual environmental conditions. As part of the article, dust samples before and after the duration of the (bio) degradation process were tested for weight loss by thermogravimetry (TG) and for losses on ignition (LOI).

4

The Influence of Various Matrixes on the Strength Properties of Moulding Sands with Thermally Hardened Hydrated Sodium Silicate for the Ablation Casting Process

Major-Gabryś Katarzyna, Puzio Sabina, Bryłka Agata, Kamińska Jadwiga

Journal of Casting & Materials Engineering

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2021

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Vol. 5, no. 2

31--35

EN

The essence of ablation casting technology consists in pouring castings into single-use moulds made from the mixture of sand and a water-soluble binder. After pouring the mould with liquid metal yet while the casting is still solidifying, the mould destruction (washing out, erosion) takes place using a stream of cooling medium, which in this case is water. This paper focuses on the selection of moulding sands with hydrated sodium silicate for moulds used in ablation casting. The research is based on the use of water glass 145 and 150 as binders. As part of the research, loose moulding mixtures based on two silica sands from different sand mines with different content of binders were prepared. The review of literature data and the results of own studies have shown that moulding sand with hydrated sodium silicate hardened by dehydration is characterized by sufficient strength properties to be used in the ablation casting process. Our own research also confirmed the possibility of using these sand mixtures in terms of both casting surface quality and sand reclamation. The results presented in this paper prove that both sand grains and types of binder tested may be used as components in moulding sands devoted to ablation casting.

5

Research on Selected Types of Lustrous Carbon Carriers After the High - Temperature Pyrolysis

Kamińska Jadwiga, Stachowicz M., Kubecki M.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 1

56--62

EN

For research purposes and to demonstrate the differences between materials obtained from the carbonaceous additives to classic green moulding sands, five lustrous carbon carriers available on the market were selected. The following carbonaceous additives were tested: two coal dusts (CD1 and CD2), two hydrocarbon resins (HR1 and HR2) and amorphous graphite (AG1). The studies of products and material effects resulting from the high-temperature pyrolysis of lustrous carbon carriers were focused on determining the tendency to gas evolution, including harmful compounds from the BTEX group (benzene, toluene, ethylbenzene and xylene). Moreover, the content of lustrous carbon (LC), the content of volatile matter and loss on ignition (LOI) of the carbonaceous additives were tested. The solid products formed during high-temperature pyrolysis were used for the quantitative and qualitative evaluation of elemental composition after the exposure to temperatures of 875oC in a protective atmosphere and 950oC in an oxidizing atmosphere. The conducted studies have indicated the necessity to examine the additives to classic green moulding sands, which is of particular importance for the processing, rebonding and storage of waste sand. The studies have also revealed some differences in the quantitative and qualitative composition of elements introduced to classic moulding sands together with the carbonaceous additives that are lustrous carbon carriers. It was also considered necessary to conduct a research on lustrous carbon carriers for their proper and environmentally friendly use in the widely propagated technology of classic green sand system.

6

Badanie homogeniczności pryzmy piasku formierskiego metodą ekstrakcji pojedynczej

Harężlak Magdalena, Kiszka Justyna, Książek Agnieszka

Analit

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2021

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Nr 10

13--24

PL

Celem eksperymentu było zbadanie homogeniczności pryzmy piasku formierskiego. W tym celu wykonano pojedynczą ekstrakcję badanego materiału za pomocą dziesięcioprocentowego roztworu kwasu azotowego (V). W tak przygotowanych próbkach oznaczono ilościowo metale takie jak żelazo i magnez przy pomocy absorpcyjnej spektroskopii atomowej. Oceny homogeniczności pryzmy piasku odlewniczego dokonano na podstawie zawartości wybranych metali (żelazo, magnez) w poszczególnych próbkach pobranych na różnych wysokościach pryzmy.

EN

The aim of the study was to investigate the homogeneity of the moulding sand prism. There was a single extraction of the tested material performed. It was conducted using a ten-percent solution of nitric acid (V). After extraction, quantitative determination of iron and magnesium was done by means of atomic absorption spectrometry method. The assessment of the homogeneity of the foundry sand prism was made on the basis of the content of iron and magnesium in individual samples collected at different heights of the prism.

7

Technological Properties of Thermo-insulating Moulding Sands with Organic Binder

Stec K., Cholewa M., Kozakiewicz Ł.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 2

105--110

EN

A thermo-insulating moulding sand with a binder made of aluminosilicate microspheres with organic binder was subjected to testing. The aim of the analysis was to determine selected technological properties of the developed compounds. Compressive strength, friability and gas permeability were determined. The binder content was changed within a range of 5÷20 wt% with a 5% step. The applied matrix is characterized by good thermo-insulating properties and a small size of grains, while synthetic organic binder has favourable functional properties, among which the most noteworthy are the extended life and setting time, good rheological properties as well as high resistance to chemical agents. The intended use of the compound is the casting of 3D CRS (Composite Reinforced Skeletons), which are characterized by a well-developed heat transfer surface area, good absorption of impact energy, low mass and a target thickness of connectors within a range of 1.5÷3 mm. The construction of 3D CRS castings is an original concept developed by the employees of the Department of Foundry Engineering at the Silesian University of Technology.

8

Studies on the Gases Emission of Moulding and Core Sands with an Inorganic Binder Containing a Relaxation Additive

Bobrowski A., Żymankowska-Kumon S., Kaczmarska K., Drożyński D., Grabowska B.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 2

19--25

EN

The paper presents the results of an investigation of the gases emission 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 in accordance with the procedure developed at the Faculty of Foundry Engineering of AGH - University of Science and Technology, on the patented stand for determining gas emissions. Quantification of BTEX compounds was performed involving gas chromatography method (GC).The study showed that the introduction of relaxation additive has no negative impact on gas emissions - both in terms of the total amount of gases generated, as well as emissions of BTEX compounds. Among the BTEX compounds, only benzene is emitted from the tested moulding sands. Its emission is associated with the introduction a small amount of an organic hardener from the group of esters.

9

Effect of Bentonite Clay Addition on the Thermal and Mechanical Properties of Conventional Moulding Sands

Kamińska J., Puzio S., Angrecki M.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 1

111--116

EN

Bentonites and clays are included in the group of drilling fluids materials. The raw materials are mainly clay minerals, which are divided into several groups, like montmorillonite, kaolinite, illite, biotite, muscovite, nontronite, anorthoclase, microcline, sanidine or rutile, differing in chemical composition and crystal lattice structure. Clay minerals have a layered structure forming sheet units. The layers merge into sheets that build up to form the structure of the mineral. The aim of the studies carried out in the ŁUKASIEWICZ Research Network - Foundry Research Institute is to explore the possibility of using minerals coming from Polish deposits. The article outlines the basic properties of hybrid bentonites, which are a mixture of bentonite clay called beidellite, originating from overburden deposits of the Turoszów Mine, and foundry bentonite from one of the Slovak deposits. As part of the physico-chemical tests of minerals, measurements included in the PN-85/H-11003 standard, i.e. montmorillonite content, water content and swelling index, were carried out. Additionally, the loss on ignition and pH chemical reaction were determined. Based on the thermal analysis of raw materials, carried out in the temperature range from 0 to 1000⁰C, changes occurring in these materials during heating, i.e. thermal stability in contact with liquid metal, were determined. Examinations of the sand mixture based on pure clay and bentonite and of the sand mixture based on hybrid bentonites enabled tracing changes in permeability, compressive strength and tensile strength in the transformation zone as well as compactability referred to the clay content in sand mixture. Selected technological and strength parameters of synthetic sands are crucial for the foundry, because they significantly affect the quality of the finished casting. Based on the analysis of the results, the optimal composition of hybrid bentonite was selected.

10

The Influence of Microwave Drying Parameters on the Properties of Synthetic Moulding Sands

Nowak D., Gal B., Włodarska A., Granat K.

Archives of Foundry Engineering

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2019

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iss. 4

51--54

EN

In this work, the influence of microwave drying parameters such as irradiation time and microwave power level on the properties of synthetic moulding sands is presented. Determination of compressive strength Rcs, shear strength Rts and permeability Ps of synthetic moulding sands with the addition of two different bentonites, after drying process with variable microwave parameters were made. The research works were carried out using the microwave oven with regulated power range of the electromagnetic field. From the results obtained, the significant influence of both drying time and microwave power level on the selected properties of moulding sands was observed. In comparison to the conventional drying method, microwave drying allows to obtain higher compressive strength of the synthetic moulding sand. The influence of application microwave irradiation on permeability was not observed. Higher strength characteristics and shorter drying time are major advantages of application of the electromagnetic irradiation for drying of the synthetic moulding sand with regard to conventional drying method.

11

Strength Properties of Ceramic Moulds Containing Spent Moulding Sand After Initial Reclamation

Angrecki M., Kamińska J., Jakubski J., Wieliczko P.

Archives of Foundry Engineering

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2019

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iss. 3

5--10

EN

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.

12

Organic Moulding Sands for Production of Large-Size Castings

Major-Gabryś K., Hosadyna-Kondracka M.

Archives of Foundry Engineering

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2019

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iss. 3

99--105

EN

Recently, some major changes have occurred in the structure of the European foundry industry, such as a rapid development in the production of castings from compacted graphite iron and light alloys at the expense of limiting the production of steel castings. This created a significant gap in the production of heavy steel castings (exceeding the weight of 30 Mg) for the metallurgical, cement and energy industries. The problem is proper moulding technology for such heavy castings, whose solidification and cooling time may take even several days, exposing the moulding material to a long-term thermal and mechanical load. Owing to their technological properties, sands with organic binders (synthetic resins) are the compositions used most often in industrial practice. Their main advantages include high strength, good collapsibility and knocking out properties, as well as easy mechanical reclamation. The main disadvantage of these sands is their harmful effect on the environment, manifesting itself at various stages of the casting process, especially during mould pouring. This is why new solutions are sought for sands based on organic binders to ensure their high technological properties but at the same time less harmfulness for the environment. This paper discusses the possibility of reducing the harmful effect of sands with furfuryl binders owing to the use of resins with reduced content of free furfuryl alcohol and hardeners with reduced sulphur content. The use of alkyd binder as an alternative to furfuryl binder has also been proposed and possible application of phenol-formaldehyde resins was considered.

13

Comparison of Molding Sand Technology Between Alphaset (APNB) and Furan (FNB)

Ghosh Dipak K.

Archives of Foundry Engineering

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2019

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iss. 4

11--20

EN

The paper focuses on investigation of properties of two most widely used self-set sand binder systems APNB and FNB across the Globe, for making molds and cores in foundries to produce castings of different sizes involving wide range of metals and alloys, ferrous and nonferrous. This includes study of compression strength values of samples made out of molding sand at different binder addition level using new, mechanically reclaimed (MR) and thermally reclaimed (TR) sand. Strength values studied include dry strength (at room temperature) at specified intervals simulating different stages of mold handling, namely stripping and pre heating, followed by degraded strength after application of thinner based zircon wash by brush, subsequent lighting of, then checking strength both in warm (degraded strength) & cold (recovered strength) conditions. Throughout the cycle of mold movement from stripping to knock out, strength requirements can be divided into two broad classifications, one from stripping to closing (dry strength) and another from pouring to knock out (hot & retained strength). Although the process for checking of dry strength are well documented, no method using simple equipments for checking hot & retained strength are documented in literature. Attempts have been made in this paper to use some simple methods to standardize process for checking high strength properties using ordinary laboratory equipments. Temperature of 450°C has been chosen by trial & error method to study high temperature properties to get consistent & amplified values. Volume of gases generated for both binders in laboratory at 850°C have also been measured. Nature of gases including harmful BTEX and PAH generated on pyrolysis of FNB and APNB bonded sands are already documented in a publication [1]. This exercise has once again been repeated in same laboratory, AGH University, Poland with latest binder formulations in use in two foundries in India.

14

Wykorzystanie odpadowych piasków odlewniczych do wykonywania mieszanek iniekcyjnych stosowanych w naprawach studzienek i rurociągów kanalizacyjnych

Mądrawski J., Kostrzewski W.

Przegląd Budowlany

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2018

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R. 89, nr 7-8

82--84

PL

W pracy przedstawiono wyniki badań laboratoryjnych dotyczących możliwości wykorzystania odpadowego piasku z odlewni aluminium. Założono, że piasek ten może być przydatny do wytwarzania mieszanek iniekcyjnych, stosowanych na wypełnienie przestrzeni w naprawianych studzienkach i kolektorach kanalizacyjnych metodą bezwykopową. Uzyskane wyniki potwierdziły wcześniejsze przypuszczenia.

EN

The paper presents the results of laboratory tests on the use of waste sand from aluminum foundry. It was assumed that this sand may be useful for the production of injection mixtures used to fill the space in repaired wells and sewage collectors. The results obtained confirmed previous assumptions.

15

Kinetics of Gases Emission from Surface Layers of Sand Moulds

Zych J., Mocek J., Kaźnica N.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

222--226

EN

Gas emission from casting moulds, cores and coatings applied for sand and permanent moulds is one of the fundamental reasons of casting defects occurrence. In the previous studies, gas emission was measured in two ways: normalized, in which the evolving gas volume was measured during heating of the moulding sand sample in a sealed flask, or by measuring the amount of gas from sand core (sample) which is produced during the pouring of liquid metal. After the pouring process the sand mould is heated very unequally, the most heated areas are layers adjacent to the liquid metal. The emission of gas is significantly larger from the surface layer than from the remaining ones. New, original method of measuring kinetics of gas emission from very thin layers of sand moulds heated by liquid metal developed by the authors is presented in the hereby paper. Description of this new method and the investigation results of kinetics of gas emission from moulding sand with furan and alkyd resin are shown. Liquid grey cast iron and Al-Si alloy were used as a heat source in the sand moulds. Comparison of the kinetics of gas emission of these two kinds of moulding sands filled with two different alloys was made. The momentary metal temperature in sand mould was assigned to the kinetics of gas emission, what creates a full view of the possibility of formation of casting defects of the gaseous origin. Moulding sand with alkyd resin is characterized by larger gas emission; however gases are emitted slower than in the case of moulding sands with furan resin. This new investigation method has a high repeatability and is the only one which gives a full view of phenomenon’s in the surface layer which determines quality of the casings. The obtained results are presented on several graphs and analyzed in detail. They have a great application value and can be used in the production of iron as well as light metal alloy castings.

16

Influence of Carbon Fibers Addition on Selected Properties of Microwave-Cured Moulding Sand Bonded with BioCo2 Binder

Grabowska B., Kaczmarska K., Cukrowicz S., Drożyński D., Żymankowska-Kumon S., Bobrowski A., Gawluk B.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 3

152--160

EN

It was found that the addition of carbon fibers (CFs) does not affect the crosslinking process in the microwave radiation (800 W, 2.45 GHz) of the BioCo2 binder, which is a water solution of poly(acrylic acid) and dextrin (PAA/D). It has influence on BioCo2 thermal properties. The CFs addition improves the thermostability of a binder and leads to the reduction of gas products quantity generated in the temperature range of 300-1100°C (TG-DTG, Py-GC/MS). Moreover, it causes the emission of harmful decomposition products such as benzene, toluene, xylene and styrene to be registered in a higher temperatures (above 700°C). BioCo2 binder without CFs addition is characterized by the emission of these substances in the lower temperature range. This indicates the positive effect of carbon fibers presence on the amount of released harmful products. The selected technological tests (permeability, friability, bending strength, tensile strength) have shown that the moulding sand with the 0.3 parts by weight carbon fibers addition displays the worst properties. The addition of 0.1 parts by weight of CFs is sufficient to obtain a beneficial effect on the analyzed moulding sands properties. The reduction of harmful substances at the higher temperatures can also be observed.

17

Influence of the Matrix Grain Size on the Apparent Density and Bending Strength of Sand Cores

Dańko R.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 1

27--30

EN

The results of investigations of the influence of the matrix grain sizes on properties of cores made by the blowing method are presented in the hereby paper. Five kinds of matrices, differing in grain size compositions, determined by the laser diffraction method in the Analysette 22NanoTec device, were applied in investigations. Individual kinds of matrices were used for making core sands in the Cordis technology. From these sands the shaped elements, for determining the apparent density of compacted sands and their bending strength, were made by the blowing method. The shaped elements (cores) were made at shooting pressures being 3, 4 and 5 atn. The bending strength of samples were determined directly after their preparation and after the storing time of 1 hour.

18

Identification Odor Compounds Emitted During the Heating of Molding Sands

Faber J., Perszewska K.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

178--182

EN

The paper presents the results of analyzes of gases emitted during exposure to high temperature foundry molding sands, where binders are organic resins. As a research tool has been used special gas chromatograph designed to identify odorous compounds including the group of alkanes.

19

Elasticity of Moulding Sands – a Method of Reducing Core Cracking

Dobosz S. M., Grabarczyk A., Major-Gabryś K.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 1

31--36

EN

This paper focuses on mechanical properties of self hardening moulding sands with furfuryl and alkyd binders. Elasticity as a new parameter of moulding sands is investigated. With the use of presented testing equipment it is possible to determine force kinetics and deformation of moulding sand in real time. The need for this kind of study comes from the modern casting industry. New foundries can be characterized with high intensity of production which is correlated with high level of mechanization and automatization of foundry processes. The increasingly common use of manipulators in production of moulds and cores can lead to generation of new types of flaws, caused by breakage in moulds and cores which could occur during mould assembly. Hence it is required that moulds and cores have high resistance to those kinds of factors, attributing it with the phenomenon of elasticity. The article describes the theoretical basis of this property, presents methods of measuring and continues earlier research.

20

Effect of Temperature on Chromite-Based Moulding Sands Bonded with Sodium Silicate

Stachowicz M., Kamiński M., Granat K., Pałyga Ł.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

95--100

EN

In the paper, a research on effects of baking temperature on chromite sand base of moulding sands bonded with sodium silicate is presented. Pure chromite sand and its chromite-based moulding sand prepared with use of sodium silicate were subjected to heating within 100 to 1200°C. After cooling-down, changes of base grains under thermal action were determined. Chromite moulding sand was prepared with use of 0.5 wt% of domestic made, unmodified sodium silicate (water-glass) grade 145. After baking at elevated temperatures, creation of rough layer was observed on grain surfaces, of both pure chromite sand and that used as base of a moulding sand. Changes of sand grains were evaluated by scanning microscopy and EDS analyses. It was found that changes on grain surfaces are of laminar nature. The observed layer is composed of iron oxide (II) that is one of main structural components of chromite sand. In order to identify changes in internal structure of chromite sand grains, polished sections were prepared of moulding sand hardened with microwaves and baked at elevated temperatures. Microscopic observations revealed changes in grains structure in form of characteristically crystallised acicular particles with limited magnesium content, intersecting at various angles. EDS analysis showed that these particles are composed mostly of chromium oxide (III) and iron oxide (II). The temperature above that the a.m. changes are observed in both chromite-based moulding sand and in pure chromite sand. The observed phenomena were linked with hardness values and mass of this sand.