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1

Taguchi Approach for Optimization of Parameters that Reduce Dimensional Variation in Investment Casting

Bansode S. N., Phalle V. M., Mantha S.

Archives of Foundry Engineering

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2019

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iss. 1

5--12

EN

Variation in final casting dimensions is a major challenge in the investment casting industry. Additional correction operations such as die tool reworking as well as coining operations affect foundry productivity significantly. In this paper influence of basic parameters such as wax material, mould material, number of ceramic coats and feed location on the dimensional accuracy of stainless-steel casting has been investigated. Two levels of each factor were chosen for experimental study. Taguchi approach has been used to design the experiment and to identify the optimal condition of each parameter for reduced dimensional deviation. Analysis of variance has been carried out to determine the contribution of each process parameter. The result reports that selected parameters have significant effect on the dimensional variability of investment casting. Mould material is the dominant parameter with the largest contribution followed by number of ceramic coats and wax material whereas feed location is having negligible contribution.

2

Thermal Reclamation of Foundry Sands Using Repurposed Sand Dryer Equipment

Sappinen T., Orkas J., Kronqvist T.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 4

99--102

EN

One of the biggest problems for sand casting foundries must be the waste produced from disposable molds. Stricter environmental regulations make it harder to dispose of waste sand, so a truly competitive foundry does no longer only make great products, but also concentrates on a sustainable casting process. While methods for repurposing waste foundry sand are still limited, the internal circulation of such sands proves significant possibilities. This paper will focus on thermal reclamation of foundry sands in a special rotating drum furnace in a central facility to serve several foundries. Thermal reclamation is a process for handling foundry sands in elevated temperatures to combust unwanted substances from reusable base sand. The introduction focuses on background of the Finnish foundry business, the most common sand systems in Finland and their reclaim properties. The experimental part features presentation of the new reclamation plant process and the conducted test runs. The samples collected from each test run have been laboratory tested to assure proper sand quality. The results of this work showed that the reclamation of alkaline phenolic no-bake sands was excellent. Reclamation of green sands did not provide satisfactory results as expected and the reclamation of furan no-bake sands provided mixed results, as the raw material was imperfect to begin with. The most important result of this work is still the successful initiation of a centralized thermal reclamation plant, with the ability to reclaim sands of several foundries. With this all of industrial symbiosis, circular economy and sustainability advanced in Finland, and the future development of this plant provides even further opportunities and a possibility to spread the ideas on a global scale.

3

Moulding Sand with Inorganic Cordis Binder for Ablation Casting

Hosadyna-Kondracka M., Major-Gabryś K., Kamińska J., Grabarczyk A., Angrecki M.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 4

110--115

EN

The essence of ablation casting technology consists in pouring castings in single-use moulds made from the mixture of sand and a water-soluble binder. After pouring the mould with liquid metal, 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 the ablation casting. The research is based on the use of Cordis binder produced by the Hüttenes-Albertus Company. It is a new-generation inorganic binder based on hydrated sodium silicate. Its hardening takes place under the effect of high temperature. As part of the research, loose moulding mixtures based on the silica sand with different content of Cordis binder and special Anorgit additive were prepared. The reference material was sand mixture without the additive. 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. Additionally, at the Foundry Research Institute in Krakow, preliminary semi-industrial tests were carried out on the use of Cordis sand technology in the manufacture of moulds for ablation casting. The possibility to use these sand mixtures has been confirmed in terms of both casting surface quality and sand reclamation.

4

Mechanical and Thermal Deformation of Hot-box Moulding Sands

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

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 4

55--58

EN

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.

5

Experimental Investigations on the Ejector Forces in the Die Casting Process

Krischke S., Müller S., Schuchardt T., Kouki Y., Dilger K.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 4

116--119

EN

A measuring system was developed for the measurement of ejector forces in the die casting process. When selecting the sensor technology, particular care was taken to ensure that measurements can be taken with a high sampling rate so that the fast-running ejection process can be recorded. For this reason, the system uses piezoelectric force sensors which measure the forces directly at the individual ejector pins. In this way, depending on the number of sensors, it is possible to determine both the individual ejector forces and the total ejector force. The system is expandable and adaptable with regard to the number and position of the sensors and can also be applied to real HPDC components. Automatic triggering of the measurements is also possible. In addition to the measuring system, a device and a method for in-situ calibration of the sensors have also been developed. To test the measuring system, casting experiments were carried out with a real aluminium HPDC aluminium component. The experiments showed that it is possible to measure the ejector forces with sufficient sampling rate and also to observe the process steps of filling, intensification and die opening by means of ejector forces. Experimental setup serves as a basis for future investigations regarding the influencing parameters on the ejection process.

6

Determination of Content of Phenol in Foundry Resins by Pyrolysis Gas Chromatography-Mass Spectrometry Method

Żymankowska-Kumon S.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 4

83--86

EN

In the foundry industry, many harmful compounds can be found, which as a result of gradual but long-term exposure to employees bring negative results. One of such compounds is phenol (aromatic organic compound), which its vapours are corrosive to the eyes, the skin, and the respiratory tract. Exposition to this compound also may cause harmful effects on the central nervous system and heart, resulting in dysrhythmia, seizures, and coma. Phenol is a component of many foundry resins, especially used in shell moulds in the form of resin-coated sands. In order to identify it, the pyrolysis gas chromatography-mass spectrometry method (Py-GC/MS) was used. The tests were carried out in conditions close to real (shell mould process – temperature 300°C). During the measurement, attention was focused on the appropriate selection of chromatographic analysis conditions in order to best separate the compounds, as it is difficult to separate the phenol and its derivatives. The identification of compounds was based on own standards.

7

Characterization of the Bonding Zone in a ZE41/AlSi12 Joint Fabricated by Liquid- Solid Compound Casting

Mola R., Bucki T.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 2

203--208

EN

The study involved using the liquid-solid compound casting process to fabricate a lightweight ZE41/AlSi12 bimetallic material. ZE41 melt heated to 660 °C was poured onto a solid AlSi12 insert placed in a steel mold. The mold with the insert inside was preheated to 300 °C. The microstructure of the bonding zone between the alloys was examined using optical microscopy and scanning electron microscopy. The chemical composition was determined through linear and point analyses with an energy-dispersive X-ray spectroscope (EDS). The bonding zone between the magnesium and aluminum alloys was about 250 μm thick. The results indicate that the microstructure of the bonding zone changes throughout its thickness. The structural constituents of the bonding zone are: a thin layer of a solid solution of Al and Zn in Mg and particles of Mg-Zn-RE intermetallic phases (adjacent to the ZE41 alloy), a eutectic region (Mg17(Al,Zn)12 intermetallic phase and a solid solution of Al and Zn in Mg), a thin region containing fine, white particles, probably Al-RE intermetallic phases, a region with Mg2Si particles distributed over the eutectic matrix, and a region with Mg2Si particles distributed over the Mg-Al intermetallic phases matrix (adjacent to the AlSi12 alloy). The microstructural analysis performed in the length direction reveals that, for the process parameters tested, the bonding zone forming between the alloys was continuous. Low porosity was observed locally near the ZE41 alloy. The shear strength of the AZ91/AlSi17 joint varied from 51.3 to 56.1 MPa.

8

The Impact of Microwave Penetration Depth on the Process of Heating the Moulding Sand with Sodium Silicate

Nowak D.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 4

115--118

EN

This paper presents the impact of microwave penetration depth on the process of heating the moulding sand with sodium silicate. For each material it is affected by: the wavelength in vacuum and the real and imaginary components of the relative complex electrical permittivity εr for a selected measurement frequency. Since the components are not constant values and they change depending on the electrical parameters of materials and the frequency of the electromagnetic wave, it is indispensable to carry out laboratory measurements to determine them. Moreover, the electrical parameters of materials are also affected by: temperature, packing degree, humidity and conductivity. The measurements of the dielectric properties of moulding sand with sodium silicate was carried out using the perturbation method on a stand of waveguide resonance cavity. The real and imaginary components of the relative complex electrical permittivity was determined for moulding sand at various contents of sodium silicate and at various packing degrees of the samples. On the basis of the results the microwave penetration depth of moulding sand with sodium silicate was established. Relative literature contains no such data that would be essential to predicting an effective process of microwave heating of moulding sand with sodium silicate. Both the packing degree and the amount of sodium silicate in moulding sand turned out to affect the penetration depth, which directly translates into microwave power density distribution in the process of microwave heating of moulding sand with sodium silicate.

9

Influence of the Al2O3 Solid Phase on the Kinetics of Binding Ceramic Moulds

Kolczyk J., Zych J., Jamrozowicz Ł.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 4

91--96

EN

The investigation results of the kinetics of binding ceramic moulds, in dependence on the solid phase content in the liquid ceramic slurries being 67, 68 and 69% - respectively, made on the basis of the aqueous binding agents Ludox AM and SK. The ultrasonic method was used for assessing the kinetics of strengthening of the multilayer ceramic mould. Due to this method, it is possible to determine the ceramic mould strength at individual stages of its production. Currently self-supporting moulds, which must have the relevant strength during pouring with liquid metal, are mainly produced. A few various factors influence this mould strength. One of them is the ceramic slurry viscosity, which influences a thickness of individual layers deposited on the wax model in the investment casting technology. Depositing of layers causes increasing the total mould thickness. Therefore, it is important to determine the drying time of each deposited layer in order to prevent the mould cracking due to insufficient drying of layers and thus the weakening of the multilayer mould structure.

10

Influence of High-Temperature Treatment of Melt on the Composition and Structure of Aluminum Alloy

Grachev V. A., Turakhodjaev N. D.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 4

61--66

EN

The aim of the current study was to examine the structure of an alloy treated at various temperatures up to 2,000–2,100 °C. Among research techniques for studying alloy structure there were the electron and optical microstructure, X-ray structure, and spectral analysis, and for studying the developed furnace geometric parameters the authors employed mathematical modeling method. The research was performed using aluminum smelting gas-fired furnaces and electric arc furnaces. The objects of the study were aluminum alloys of the brand AK7p and AK6, as well as hydrogen and aluminum oxide in the melt. For determining the hydrogen content in the aluminum alloy, the vacuum extraction method was selected. Authors have established that treatment of molten aluminum alloy in contact with carbon melt at high temperatures of 2,000–2,100 °C has resulted in facilitating reduction of hydrogen and aluminum oxide content in the melt by 40-43% and 50-58%, respectively, which is important because hydrogen and aluminum oxide adversely affect the structure and properties of the alloy. Such treatment contributes to the formation of the extremely fine-grained microstructure of aluminum alloy.

11

Electrical Properties of Multilayer Systems Composed of Foundry Tooling and Moulding Sand

Gal B., Granat K.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

21--24

EN

Within the research, selected multilayer technological systems created as combinations of water-glass containing moulding sand with foundry tooling, were characterised on the grounds of their electrical properties. By measuring resonance frequency and quality factor of a waveguide resonance cavity, real component of permittivity εr′ and loss tangent tgδ were determined for multilayer foundry systems with various qualitative and quantitative compositions. It was demonstrated that combination of a sandmix and foundry tooling with known dielectric properties results in a system with different physico-chemical properties, whose relation to the parameters of individual components of the system is undefined at this research stage. On the grounds of measurement results, theoretical value of microwave heating power, dissipated in unit volume of the selected multilayer foundry system, was determined. Knowledge of theoretical heating power and evaluation of physical, chemical and structural changes occurring in moulding sands exposed to microwaves in such a technological system makes a ground for empirical modelling of the process of microwave heating of foundry moulds and cores.

12

The Flexibility of Pusher Furnace Grate

Słowik J. A., Drotlew A., Piekarski B.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

137--140

EN

The lifetime of guide grates in pusher furnaces for heat treatment could be increased by raising the flexibility of their structure through, for example, the replacement of straight ribs, parallel to the direction of grate movement, with more flexible segments. The deformability of grates with flexible segments arranged in two orientations, i.e. crosswise (perpendicular to the direction of compression) and lengthwise (parallel to the direction of compression), was examined. The compression process was simulated using SolidWorks Simulation program. Relevant regression equations were also derived describing the dependence of force inducing the grate deformation by 0.25 mm ‒ modulus of grate elasticity ‒ on the number of flexible segments in established orientations. These calculations were made in Statistica and Scilab programs. It has been demonstrated that, with the same number of segments, the crosswise orientation of flexible segments increases the grate structure flexibility in a more efficient way than the lengthwise orientation. It has also been proved that a crucial effect on the grate flexibility has only the quantity and orientation of segments (crosswise / lengthwise), while the exact position of segments changes the grate flexibility by less than 1%.

13

The Compositions: Biodegradable Material – Synthetic Resins as Moulding Sands Binders

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

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

75--78

EN

Growing emission requirements are forcing the foundry industry to seek new, more environmentally friendly solutions. One of the solutions may be the technologies of preparing moulding and core sands using organic biodegradable materials as binders. However, not only environmental requirements grow but also those related to the technological properties of moulding sand. Advancing automation and mechanization of the foundry industry brings new challenges related to the moulding sands. Low elasticity may cause defects during assembly of cores or moulds by the manipulators. The paper presents the study of flexibility in the room temperature according to new method and resistance to thermal deformation of self-hardening moulding sands with furfuryl resin, containing biodegradable material PCL. The task of the new additive is to reduce the moulding sands harmfulness to the environment and increase its flexibility in the room temperature. The impact of the additive and the effect of the amount of binder on the properties of mentioned moulding sands were analysed. Studies have shown that the use of 5% of PCL does not change the nature of the thermal deformation curve, improves the bending strength of tested moulding mixtures and increases their flexibility at room temperature.

14

Microstructure of Cast High-Manganese Steel Containing Titanium

Tęcza G., Garbacz-Klempka A.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

163--168

EN

Widely used in the power and mining industry, cast Hadfield steel is resistant to wear, but only when operating under impact loads. Components made from this alloy exposed to the effect of abrasion under load-free conditions are known to suffer rapid and premature wear. To increase the abrasion resistance of cast high-manganese steel under the conditions where no dynamic loads are operating, primary titanium carbides are formed in the process of cast steel melting, to obtain in the alloy after solidification and heat treatment, the microstructure composed of very hard primary carbides uniformly distributed in the austenitic matrix of a hardness superior to the hardness of common cast Hadfield steel. Hard titanium carbides ultimately improve the wear resistance of components operating under shear conditions. The measured microhardness of the as-cast matrix in samples tested was observed to increase with the increasing content of titanium and was 380 HV0.02 for the content of 0.4%, 410 HV0.02 for the content of 1.5% and 510 HV0.02 for the content of 2 and 2.5%. After solution heat treatment, the microhardness of the matrix was 460÷480 HV0.02 for melts T2, T3 and T6, and 580 HV0.02 for melt T4, and was higher than the values obtained in common cast Hadfield steel (370 HV0.02 in as-cast state and 340÷370 HV0.02 after solution heat treatment). The measured microhardness of alloyed cementite was 1030÷1270 HV0.02; the microhardness of carbides reached even 2650÷4000 HV0.02.

15

Investigations of Ferritic Nodular Cast Iron Containing About 5-6% Aluminium

Soiński M. S., Kordas P., Skurka K., Jakubus A.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

141--146

EN

The work presents results of investigations concerning the production of cast iron containing about 5-6% aluminium, with the ferritic matrix in the as-cast state and nodular or vermicular graphite precipitates. The examined cast iron came from six melts produced under the laboratory conditions. It contained aluminium in the amount of 5.15% to 6.02% (carbon in the amount of 2.41% to 2.87%, silicon in the amount of 4.50% to 5.30%, and manganese in the amount of 0.12% to 0.14%). After its treatment with cerium mixture and graphitization with ferrosilicon (75% Si), only nodular and vermicular graphite precipitates were achieved in the examined cast iron. Moreover, it is possible to achieve the alloy of pure ferritic matrix, even after the spheroidizing treatment, when both the aluminium and the silicon occur in cast iron in amounts of about 5.2÷5.3%.

16

Enhancement of Heat Transfer in PCM by Cellular Zn-Al Structure

Naplocha K., Koniuszewska A., Lichota J., Kaczmar J. W.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

91--94

EN

Development of open cellular metal foam technology based on investment casting applying the polyurethane pattern is discussed. Technological process comprises preparing of the ceramic mold applying PUR foam as the pattern, firing of the mold, pouring of the liquid Zn-Al alloy into the mold and washing out of the ceramic material from cellular casting. Critical parameters such as the temperature of mold and poured metal, design of gating system affected by metalostatic pressure allowed to produce castings with cellular structure characterized by the open porosity. Metal cellular foams with the open porosity embedded in phase change material (PCM) enhance heat transfer and reduce time operations in energy storage systems. Charging and discharging were performed at the laboratory accumulator by heating and cooling with flowing water characterized by the temperatures of 97-100ºC. Temperature measurements were collected from 7 different thermocouples located in the accumulator. In relation to the tests with pure paraffin, embedding of the metal Zn-Al cellular foam in paraffin significantly decreases temperature gradients and melting time of paraffin applied as PCM characterized by the low thermal conductivity. Similarly, reduction of discharging time by this method improves the efficiency of thermal energy storage system applied in solar power plants or for the systems of energy efficient buildings.

17

Effect of Casting Die Cooling on Solidification Process and Microstructure of Hypereutectic Al-Si Alloy

Władysiak R., Kozuń A., Pacyniak T.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

175--180

EN

The work is a continuation of research concerning the influence of intensive cooling of permanent mold in order to increase the casting efficiency of aluminium alloys using the multipoint water mist cooling system. The paper presents results of investigation of crystallization process and microstructure of synthetic hypereutectic alloys: AlSi15 and AlSi19. Casts were made in permanent mold cooled with water mist stream. The study was conducted for unmodified silumins on the research station allowing the cooling of the special permanent probe using a program of computer control. Furthermore the study used a thermal imaging camera to analyze the solidification process of hypereutectic silumins. The study demonstrated that the use of mold cooled with water mist stream allows in wide range the formation of the microstructure of hypereutectic silumins. It leads to higher homogeneity of microstructure and refinement of crystallizing phases and also it increases subsequently the mechanical properties of casting.

18

Wpływ rodzaju, grubości pokrycia ceramicznego oraz gęstości zespołu modelowego na stopień zagazowania odlewu

Buczkowska K., Just P., Świniarska J., Pacyniak T.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 2 spec.

7--12

PL

W pracy poruszone zostały zagadnienia związane z technologią lost foam. Zbadano wpływ rodzaju oraz grubości pokrycia ceramicznego a także gęstości zespołu modelowego na stopień zagazowania odlewu. Badania przeprowadzono dla dwóch rodzajów pokryć ceramicznych Disopast 4805/3 oraz Disopast 7759, które nakładano na modele ze spienionego polistyrenu w jednej, dwóch i trzech warstwach. Tak przygotowane modele wykorzystano do wytworzenia odlewów ze stopu AlSi11 w technologii lost foam. Otrzymane odlewy zbadano pod kątem stopnia ich zagazowania. Zaprezentowane badania wykazały zależności pomiędzy gęstością modelu, rodzajem i grubością zastosowanych powłok ceramicznych, a stopieniem zagazowania odlewów. Wykazano, że badane właściwości mają istotny wpływ na stopień zagazowania odlewu, jego porowatość oraz liczbę gazową. Poprzez odpowiedni dobór pokrycia, jego grubości, gęstości modelu, możliwe jest zminimalizowanie stopnia zagazowania odlewu.

EN

The study addressed the issues associated with lost foam casting technology. The effect of the type and thickness of the ceramic coating and the density of the pattern set of the degree of gas porosity in casting. The study was conducted for two types of ceramic coatings Disopast 4805/3 and Disopast 7759, which was applied to patterns with expanded polystyrene in one, two and three layers. Thus prepared patterns were used to produce castings alloy AlSi11 lost foam technology. The resulting castings were tested for their level of gas porosity. Presented studies have shown the relationship between the density of the polystyrene pattern, type and thickness of the applied ceramic coatings gas porosity and casting melt. It has been shown that investigated the properties have a significant impact on the degree of gas porosity in cast, its porosity and the gaseous number. Through an appropriate choice of coating, its thickness, density model, it is possible to minimize the degree of gassing casting.

19

The Production of Plaster Molds with Patternless Process Technology

Pastirčák R., Sládek A., Kucharčíková E.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 2

91--94

EN

The work deals with technology Patternless process that combines 3 manufacturing process mold by using rapid prototyping technology, conventional sand formation and 3D milling. It's unconventional technology that has been developed to produce large-sized and heavy duty castings weighing up to several tons. It is used mainly in prototype and small batch production, because eliminating production of models. The work deals with the production of blocks for making molds of gypsum and gypsum drying process technology Thermomold. Into blocks, where were made cavities by milling were casted test castings from AlSi10MgMn alloy by gravity casting. At machining of the mold cavity was varied feed rate of tool of cemented carbide. Evaluated was the surface roughness of test castings, that was to 5 micrometers with feed from 900 to 1300 mm/min. The dimensional accuracy of castings was high at feed rate of 1000 and 1500 mm/min did not exceed 0.025 mm.

20

The Influence of Sand Grains Properties on Electrical Properties of Moulding Sand with Inorganic Binder

Opyd B., Granat K.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 3

43--46

EN

The paper presents the results of basic research on the influence of the properties of sand grains on electrical properties of water glass moulding sands. It shows electrical properties of the main component – sand grains, crucial to the kinetics of moulding sands heating, such as permittivity εr and loss factor tgδ. Measurements were carried out with the use of the perturbation method for silica, chromite and olivine sands of different mineral, chemical composition and particle size distribution, as well as for moulding sands with water glass grade 145. Analysis of the results of measurements of electrical properties shows that all moulding sands are characterized by a similar permittivity εr and loss factor tgδ. It was found that the electrical properties and the quantity and quality of other components may have a decisive influence on the effectiveness and efficiency of the microwave heating of moulding sands with sand grains. In determining the ability to efficiently absorb the microwave radiation for mixtures which moulding sands are, the impact of all components influencing their individual technological parameters should be taken into account.