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Rafał Dańko - One of the best experts on this subject based on the ideXlab platform.

  • Environmental Impact of the Reclaimed Sand Addition to Molding Sand with Furan and Phenol-Formaldehyde Resin-A Comparison.
    Materials (Basel Switzerland), 2020
    Co-Authors: Mariusz Holtzer, D. Drożyński, Rafał Dańko, Angelika Kmita, M. Kubecki, M. Skrzyński, A. Roczniak
    Abstract:

    Increasingly strict regulations, as well as an increased public awareness, are forcing industry, including the foundry industry, to develop new binders for Molding Sands, which, while being more environmentally friendly, would simultaneously ensure a high quality of castings. Until recently, binders based on synthetic resins were considered to be such binders. However, more accurate investigations indicated that such Molding Sands subjected to high temperatures of liquid metal generated several harmful, even dangerous substances (carcinogenic and/or mutagenic) from the benzene, toluene, ethylbenzene and xylenes (BTEX) and polycyclic aromatic hydrocarbons groups (PAHs). An assessment of the most widely used Molding Sands technologies at present with organic binders (synthetic resins) from the no-bake group (furan no-bake and phenolic-ester no-bake) and their harmfulness to the environment and work conditions is presented in this paper. In the first stage of this research, gases (from the BTEX and PAHs groups) emitted when the tested molds were poured with liquid cast iron at 1350 °C were measured (according to the authors' own method). The second stage consisted of measuring the emission of gases released by binders subjected to pyrolysis (the so-called flash pyrolysis), which simulated the effects occurring on the boundary: liquid metal/Molding Sand. The gases emitted from the tested binders indicated that, in both cases, the emission of harmful and dangerous substances (e.g., benzene) occurs, but, of the given binder systems, this emission was lower for the phenolic-ester no-bake binder. The obtained emission factors of BTEX substances show higher values for furan resin compared to formaldehyde resin; for example, the concentration of benzene per 1 kg of binder for furan no-bake (FNB) was 40,158 mg, while, for phenol-formaldehyde no-bake (PFNB), it was much lower, 30,911 mg. Thus, this system was more environmentally friendly.

  • Methods of the Mold Sands Quality Assessment
    Microstructure and Properties of Ductile Iron and Compacted Graphite Iron Castings, 2015
    Co-Authors: Rafał Dańko
    Abstract:

    This chapter on methods for assessing the quality of the matrix and Molding Sand presents the most important properties of these materials, from the point of view of the feasibility of using these Molding Sands for producing sound castings. In the case of matrix testing (both fresh and reclaimed), attention was drawn to the size and shape of the grain, which have a decisive influence on the permeability of the Molding Sand, on the content and the activity of the binder for the matrix used for the preparation of green Sand, loss on ignition and the chemical nature of the matrix evaluated on the basis of the parameters such as ADV and pH. The next section presents complementary research methods of Molding Sand properties with reclaimed Sand. Modern systems require evaluation and a careful approach to the factors that determine Molding Sand suitability for both technological use as well as the impact on the surrounding environment. In this context, a full evaluation of the quality of the reclaimed matrix goes beyond the usual instrumental methods and requires the addition of advanced apparatus research methods. This allows one to put the evaluation of the reclaimed matrix into perspective, both in terms of its use for the preparation of Molding Sand, as a substitute for fresh Sand, and also in terms of environmental protection. Such modern methods may include, inter alia, an assessment of gas excretion in Molding Sand, identification of the type of emitted gases, the content of BTEX gases that are particularly dangerous to humans, and the evaluation of the surface of the casting made in Molding Sand with reclaimed Sand.

  • Molds and Cores Systems in Foundry
    Microstructure and Properties of Ductile Iron and Compacted Graphite Iron Castings, 2015
    Co-Authors: Mariusz Holtzer, Rafał Dańko
    Abstract:

    Sand binding systems can have a significant impact on the nature of the casting skin formation. In particular, the binder containing elements such as S, O and N may adversely affect the structure of the layer. As in the case of spheroidal graphite cast iron (SGI) and compacted graphite cast iron (CGI) main factor causing the degeneration of graphite in the surface layer of the casting is sulfur, therefore these binding systems (binder) which contain sulfur have been thoroughly discussed here. The following are Sand mold technologies: furan, acid catalyzed, phenolic, acid catalyzed, hot box, warm box and Shell (Croning) process. Sand Molding with the use of furfuryl resins technology is presented in detail due to their widespread use in casting both cast iron and cast steel. To reduce the thickness of the surface layer, which may be the adverse effect of sulfur on the degeneracy of the graphite, S content in Molding Sand should be less than 0.15 % mass, and even below 0.07 % mass. Sand binding systems can have a significant impact on the nature of casting skin formation. In the case of green Sand, moisture promotes the formation of the ferritic rim (Reisener, Br Foundryman 55:362–369, 1962; Matijasevic et al. Trans AFS 82:571–622, 1974; Narasimha and Wallace, AFS Trans 83:531–550, 1975). Research carried out for Sand mold with sodium silicate and phenolic urethane has shown that SGI and CGI castings made in the first Sand mold is pearlitic rim occurred, and in the second Sand mold this occurrence is not found (Boonmee and Stefanescu, Foundry Trade J 186:225–228, 2012). Regarding the effect of the Molding Sand on the nature of the casting skin formation, they can be divided into Molding Sand: with binders containing sulfur (i.e. furfuryl alcohol and urea-formaldehyde resin) and the Molding Sand that are not bound with binders not containing sulfur (i.e. phenol-urethane resin ). From the point of view of the top layer the sulfur-containing Molding Sand is much more important, due to its adverse effect on the formation of spheroidal graphite.

  • Effect of Reclamation on the Skin Layer of Ductile Iron Cast in Furan Molds
    Journal of Materials Engineering and Performance, 2013
    Co-Authors: Rafał Dańko, Mariusz Holtzer, Marcin Górny, S. Żymankowska-kumon
    Abstract:

    The paper presents the results of investigations of the influence of the quality of Molding Sand with furan resin hardened by paratoluenesulfonic acid, on the formation of microstructure and surface quality of ductile iron castings. Within the studies different Molding Sands were used: Molding Sand prepared with fresh Sand and Molding Sands prepared with reclaimed Sands of a different purification degree, determined by the ignition loss value. Various concentrations of sulfur and nitrogen in the Sand molds as a function of the ignition loss were shown in the paper. A series of experimental melts of ductile iron in molds made of Molding Sand characterized by different levels of surface-active elements (e.g., sulfur) and different gas evolution rates were performed. It was shown that there exists a significant effect of the quality of the Sand on the formation of the graphite degeneration layer.

Mariusz Holtzer - One of the best experts on this subject based on the ideXlab platform.

  • Environmental Impact of the Reclaimed Sand Addition to Molding Sand with Furan and Phenol-Formaldehyde Resin-A Comparison.
    Materials (Basel Switzerland), 2020
    Co-Authors: Mariusz Holtzer, D. Drożyński, Rafał Dańko, Angelika Kmita, M. Kubecki, M. Skrzyński, A. Roczniak
    Abstract:

    Increasingly strict regulations, as well as an increased public awareness, are forcing industry, including the foundry industry, to develop new binders for Molding Sands, which, while being more environmentally friendly, would simultaneously ensure a high quality of castings. Until recently, binders based on synthetic resins were considered to be such binders. However, more accurate investigations indicated that such Molding Sands subjected to high temperatures of liquid metal generated several harmful, even dangerous substances (carcinogenic and/or mutagenic) from the benzene, toluene, ethylbenzene and xylenes (BTEX) and polycyclic aromatic hydrocarbons groups (PAHs). An assessment of the most widely used Molding Sands technologies at present with organic binders (synthetic resins) from the no-bake group (furan no-bake and phenolic-ester no-bake) and their harmfulness to the environment and work conditions is presented in this paper. In the first stage of this research, gases (from the BTEX and PAHs groups) emitted when the tested molds were poured with liquid cast iron at 1350 °C were measured (according to the authors' own method). The second stage consisted of measuring the emission of gases released by binders subjected to pyrolysis (the so-called flash pyrolysis), which simulated the effects occurring on the boundary: liquid metal/Molding Sand. The gases emitted from the tested binders indicated that, in both cases, the emission of harmful and dangerous substances (e.g., benzene) occurs, but, of the given binder systems, this emission was lower for the phenolic-ester no-bake binder. The obtained emission factors of BTEX substances show higher values for furan resin compared to formaldehyde resin; for example, the concentration of benzene per 1 kg of binder for furan no-bake (FNB) was 40,158 mg, while, for phenol-formaldehyde no-bake (PFNB), it was much lower, 30,911 mg. Thus, this system was more environmentally friendly.

  • Other Molding and Core Sands with Inorganic Binders
    Mold and Core Sands in Metalcasting: Chemistry and Ecology, 2020
    Co-Authors: Mariusz Holtzer, Angelika Kmita
    Abstract:

    GEOPOL® is a unique inorganic binder system. This technology is currently used in the foundries for three basic production technologies: (a) self-setting Molding Sand, (b) Molding Sand hardened by gaseous CO2, (c) and the hot-box technology by hot air hardened.

  • The Mold/Casting Interface Phenomena
    Microstructure and Properties of Ductile Iron and Compacted Graphite Iron Castings, 2015
    Co-Authors: Mariusz Holtzer
    Abstract:

    Many of surface defects in casting are caused by interaction of the metal with the Molding Sand. These phenomena occurring on the mold/cast interface can be divided into three groups: metal penetration (mechanical, chemical, vapor state, water explosion penetration and eutectic exudation penetration); transition of elements from the Molding Sand into casting and from the casting into the mold and gas generation by thermal decomposition of the binder and/or coating. Transition of the casting elements such as P, N, H, C, S, Si from the Molding Sand to the surface layer of the casting and elements such as Mn, C from casting to the Molding Sand is also possible. Frequently, this can cause changes in the chemical composition of the surface layer of the casting, which may consequently lead to changes in the casting microstructure and properties. Gases emitted from the Molding Sand, core or protective coating during pouring liquid metal are often due to the cause of the so-called gas porosity. The rate of the evolution of gases from the mold and cores, and their volume depends strongly on the binder used. Air present in the mold cavity may also be the cause of porosity.

  • Molds and Cores Systems in Foundry
    Microstructure and Properties of Ductile Iron and Compacted Graphite Iron Castings, 2015
    Co-Authors: Mariusz Holtzer, Rafał Dańko
    Abstract:

    Sand binding systems can have a significant impact on the nature of the casting skin formation. In particular, the binder containing elements such as S, O and N may adversely affect the structure of the layer. As in the case of spheroidal graphite cast iron (SGI) and compacted graphite cast iron (CGI) main factor causing the degeneration of graphite in the surface layer of the casting is sulfur, therefore these binding systems (binder) which contain sulfur have been thoroughly discussed here. The following are Sand mold technologies: furan, acid catalyzed, phenolic, acid catalyzed, hot box, warm box and Shell (Croning) process. Sand Molding with the use of furfuryl resins technology is presented in detail due to their widespread use in casting both cast iron and cast steel. To reduce the thickness of the surface layer, which may be the adverse effect of sulfur on the degeneracy of the graphite, S content in Molding Sand should be less than 0.15 % mass, and even below 0.07 % mass. Sand binding systems can have a significant impact on the nature of casting skin formation. In the case of green Sand, moisture promotes the formation of the ferritic rim (Reisener, Br Foundryman 55:362–369, 1962; Matijasevic et al. Trans AFS 82:571–622, 1974; Narasimha and Wallace, AFS Trans 83:531–550, 1975). Research carried out for Sand mold with sodium silicate and phenolic urethane has shown that SGI and CGI castings made in the first Sand mold is pearlitic rim occurred, and in the second Sand mold this occurrence is not found (Boonmee and Stefanescu, Foundry Trade J 186:225–228, 2012). Regarding the effect of the Molding Sand on the nature of the casting skin formation, they can be divided into Molding Sand: with binders containing sulfur (i.e. furfuryl alcohol and urea-formaldehyde resin) and the Molding Sand that are not bound with binders not containing sulfur (i.e. phenol-urethane resin ). From the point of view of the top layer the sulfur-containing Molding Sand is much more important, due to its adverse effect on the formation of spheroidal graphite.

  • Effect of Reclamation on the Skin Layer of Ductile Iron Cast in Furan Molds
    Journal of Materials Engineering and Performance, 2013
    Co-Authors: Rafał Dańko, Mariusz Holtzer, Marcin Górny, S. Żymankowska-kumon
    Abstract:

    The paper presents the results of investigations of the influence of the quality of Molding Sand with furan resin hardened by paratoluenesulfonic acid, on the formation of microstructure and surface quality of ductile iron castings. Within the studies different Molding Sands were used: Molding Sand prepared with fresh Sand and Molding Sands prepared with reclaimed Sands of a different purification degree, determined by the ignition loss value. Various concentrations of sulfur and nitrogen in the Sand molds as a function of the ignition loss were shown in the paper. A series of experimental melts of ductile iron in molds made of Molding Sand characterized by different levels of surface-active elements (e.g., sulfur) and different gas evolution rates were performed. It was shown that there exists a significant effect of the quality of the Sand on the formation of the graphite degeneration layer.

Sermsak Wiengwiset - One of the best experts on this subject based on the ideXlab platform.

  • Optimization of Molding Sand composition for quality improvement of iron castings
    Applied Clay Science, 2012
    Co-Authors: Charnnarong Saikaew, Sermsak Wiengwiset
    Abstract:

    Abstract In the iron casting industry, the quality of the Sand mold is important for foundry manufacturers to achieve high quality iron castings. The aim of this research was to optimize the proportion of bentonite and water added to a recycled Sand mold for reducing iron casting waste using the following analysis techniques: a mixture experimental design, response surface methodology, and propagation of error. The effects of variation in bentonite and water added to a recycled Sand mold on the properties of the Molding Sand were investigated. The iron castings were measured qualitatively using a stereo microscope and its surface hardness was also measured using a Rockwell hardness testing machine. The research concluded that the optimal proportion was 93.3 mass% of one-time recycled Molding Sand, 5 mass% of bentonite, and 1.7 mass% of water having a green compression strength of 53,090 N/m 2 and a permeability of 30 A.F.S.

Jin Xiao-hai - One of the best experts on this subject based on the ideXlab platform.

  • Adaptability of Natural Yellow Loam Clay-Bonded Sand Casting Process to Thickness of Iron Castings
    2009
    Co-Authors: Jin Xiao-hai
    Abstract:

    Tests of moldability and pouring of HT150 cast iron were carried out on natural clay-bonded Sand with four different formulas. Firstly, the formula of natural clay bonded Sand with the best moldability was selected according to the former's experience and the results of Molding. Then, the best casting process was achieved by analyzing iron casting's surface quality(Sand burn on and roughness)and the sintering shell of the Molding Sand. Finally, the proper thickness range of iron casting adapt for natural clay bonded Sand casting process was obtained.

  • Application of Green Sand Casting Process of Yellow Loam Natural Clay-Bonded Sand
    2009
    Co-Authors: Jin Xiao-hai
    Abstract:

    At present,the foundry industry that applied green Sand casting with pulverized coal clay bonded Sand has suffered severe pollution,high consumption,and poor quality of casting surface,which is not in accordance with the current industrial policy of energy-saving and consumption-reducing.Thus,to explore a resource-conserving green casting process has great practical significance.Natural yellow loam clay bonded Sand is composed of yellow loam and slag,compared with pulverized coal clay bonded Sand,it shows a series of advantages in production of cast iron such as the recycle using of Molding Sand and less emission of waste Sand;no penetration or burn on in the casting's surface,high dimensional accuracy,low surface roughness and high productivity;the Sand is rich in resource and can be obtained from the local areas.In order to achieve large-scale applications of natural yellow loam clay-bonded Sand green casting process,the applicability of Molding Sand with different kinds of yellow loam,different contents of slag and moisture in the production of motor shell casting of sewing machine has been investigated on the basis of the orthogonal test method.Process performances of Molding Sand such as strength,permeability were tested.The obtained formula and technology are applied to the mass production in factories,and significant results have been achieved.

Hong Hocheng - One of the best experts on this subject based on the ideXlab platform.

  • The flowability of bentonite bonded green Molding Sand
    Journal of Materials Processing Technology, 2001
    Co-Authors: Y Chang, Hong Hocheng
    Abstract:

    Abstract This paper investigates the properties of green Molding Sands, and a new model to evaluate the flowability of Sand compact is developed. Controlling the flowability of the Molding Sand is extremely important in the Sand casting process. Although several flowability indices have been proposed to measure this property, none of them has been universally adopted as a reliable indicator of the flowability. In this study, experimental results are presented to show how the flowability of silica Sand is affected by water content, bentonite and sea-coal content. The equation proposed by Shapiro and Kolthoff can well fit the relationship between the compacting pressure and the relative density. The coefficients of S–K equation were substituted into the strength equation proposed by Sheppard and McShane. The S–M equation matches the green compaction strength data, with an error less than 5%. The model reported here correlates a one-dimensional compaction model with the S–M and S–K equations, and derives the relative density difference and the compression strength difference of the compact. The experimental results showed that the green strength reached the maximum at the ratio of moisture-to-bentonite of around 0.33. The hardness deviation on the central plane of the compact was taken as the reference to test the estimated strength difference. The results indicated that the flowability increased as the water content decreased. The model can explain the experimental results and directly predicts the uniformity of the compact. The estimated relative density difference ΔDr can be a new index of the flowability. For lowest ΔDr, the best water content occurs at around w%=3.0.

  • The flowability of bentonite bonded green Molding Sand
    Journal of Materials Processing Technology, 2001
    Co-Authors: Y Chang, Hong Hocheng
    Abstract:

    [[abstract]]This paper investigates the properties of green Molding Sands, and a new model to evaluate the flowability of Sand compact is developed. Controlling the flowability of the Molding Sand is extremely important in the Sand casting process. Although several flowability indices have been proposed to measure this property, none of them has been universally adopted as a reliable indicator of the flowability. In this study, experimental results are presented to show how the flowability of silica Sand is affected by water content, bentonite and sea-coal content. The equation proposed by Shapiro and Kolthoff can well fit the relationship between the compacting pressure and the relative density. The coefficients of S-K equation were substituted into the strength equation proposed by Sheppard and McShane. The S-M equation matches the green compaction strength data, with an error less than 5%. The model reported here correlates a one-dimensional compaction model with the S-M and S-K equations, and derives the relative density difference and the compression strength difference of the compact. The:experimental results showed that the green strength reached the maximum at the ratio of moisture-to-bentonite of around 0.33. The hardness; deviation on the central plane of the compact was taken as the reference to test the estimated strength difference. The results indicated that the flowability increased as the water content decreased. The model can explain thr experimental results and directly predicts the uniformity of the compact. The estimated relative density difference DeltaD(r) can be a new index of the flowability. For lowest DeltaD(D) the best water content occurs at around w% = 3.0. (C) 2001 Elsevier Science B.V. All rights reserved.[[fileno]]2020212010056[[department]]動機