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Abstrakt

Modern techniques of castings production, including moulding sands production, require a strict technological regime and high quality materials. In the case of self-hardening moulding sands with synthetic binders those requirements apply mainly to sand, which adds to more than 98% of the whole moulding sand mixture. The factors that affect the quality of the moulding sands are both chemical (SiO2 , Fe2O3 and carbonates content) and physical. Among these factors somewhat less attention is paid to the granulometric composition of the sands. As a part of this study, the effect of sand quality on bending strength Rgu and thermal deformation of self-hardening moulding sands with furfural and alkyd resin was assessed. Moulding sands with furfural resin are known [1] to be the most susceptible to the sand quality. A negative effect on its properties has, among others, high content of clay binder and so-called subgrains (fraction smaller than 0,1mm), which can lead to neutralization of acidic hardeners (in the case of moulding sands with furfuryl resin) and also increase the specific surface, what forces greater amount of binding agents. The research used 5 different quartz sands originating from different sources and characterized with different grain composition and different clay binder content.
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The paper presents the impact of biodegradable material - polycaprolactone (PCL) on selected properties of moulding sands. A self-hardening moulding sands with phenol-furfuryl resin, which is widely used in foundry practice, and an environmentally friendly self-hardening moulding sand with hydrated sodium silicate where chosen for testing. The purpose of the new additive in the case of synthetic resin moulding sands is to reduce their harmfulness to the environment and to increase their “elasticity” at ambient temperature. In the case of moulding sands with environmentally friendly hydrated sodium silicate binder, the task of the new additive is to increase the elasticity of the tested samples while preserving their ecological character. Studies have shown that the use of 5% PCL in moulding sand increases their flexibility at ambient temperature, both with organic and inorganic binders. The influence of the new additive on the deformation of the moulding sands at elevated temperatures has also been demonstrated.
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Abstrakt

The paper presents possibility of using biodegradable materials as parts of moulding sands’ binders based on commonly used in foundry practice resins. The authors focus on thermal destruction of binding materials and thermal deformation of moulding sands with tested materials. All the research is conducted for the biodegradable material and two typical resins separately. The point of the article is to show if tested materials are compatible from thermal destruction and thermal deformation points of view. It was proved that tested materials characterized with similar thermal destruction but thermal deformation of moulding sands with those binders was different.
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Abstrakt

Due to the presence of harmful substances in resins those mould sands may be hazardous to the natural environment and workers. The general assessment of harmfulness of sands used for molds and cores encompasses 2 basic points: emission of hazardous substances during processes of preparing sands, pouring mold with liquid metals (high temperatures), cooling and shaking-out; possibility of washing out hazardous substances from used sands to the environment, during storage or economic use outside foundries. We present the results of research on the emission of BTEX compounds from mould sands with phenolic resins during pouring liquid metal of different temperature (cast iron and Al alloy). The research was conducted according to the original method prepared by the authors, which has been used for years in cooperation with various foundries (Poland, abroad).
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Abstrakt

Artificial neural networks are one of the modern methods of the production optimisation. 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 aimed at the selection of the neural network able to predict the active bentonite content in the moulding sand on the basis of this sand properties such as: permeability, compactibility and the compressive strength. Then, the data of selected parameters of new moulding sand were set to selected artificial neural network models. This was made to test the universality of the model in relation to other moulding sands. An application of the Statistica program allowed to select automatically the type of network proper for the representation of dependencies occurring in between the proposed moulding sand parameters. The most advantageous conditions were obtained for the uni-directional multi-layer perception (MLP) network. Knowledge of the neural network sensitivity to individual moulding sand parameters, allowed to eliminate not essential ones.
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This paper presents a new perspective on the issue of reclamation of moulding and core sands. Taking as a premise that the reclamation process must remain on the surface of grains some not separated binding materials rests, it should be chosen the proper moulding sand’s composition that will be least harmful for the reclaim quality. There are two different moulding and core sands taken into examinations. The researches prove that a small correction of their compositions (hardener type) improves the quality of the received reclaims. Carried out in this article studies have shown that such an approach to the problem of reclamation of the moulding and core sands is needed and reasonable.
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The article shows the influence of environment requirements on changes in different foundry moulding sands technologies such as cold box, self-hardening moulding sands and green sands. The aim of the article is to show the possibility of using the biodegradable materials as binders (or parts of binders’ compositions) for foundry moulding and core sands. The authors concentrated on the possibility of preparing new binders consisting of typical synthetic resins - commonly used in foundry practice - and biodegradable materials. According to own research it is presumed that using biodegradable materials as a part of new binders’ compositions may cause not only lower toxicity and better ability to reclaim, but may also accelerate the biodegradation rate of used binders. What’s more, using some kinds of biodegradable materials may improve flexibility of moulding sands with polymeric binder. The conducted research was introductory and took into account bending strength and thermal properties of furan moulding sands with biodegradable material (PCL). The research proved that new biodegradable additive did not decrease the tested properties.
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Abstrakt

The necessity of obtaining high quality castings forces both researchers and producers to undertake research in the field of moulding sands. The key is to obtain moulding and core sands which will ensure relevant technological parameters along with high environmental standards. The most important group in this research constitutes of moulding sands with hydrated sodium silicate. The aim of the article is to propose optimized parameters of hardening process of moulding sands with hydrated sodium silicate prepared in warm-box technology. This work focuses on mechanical and thermal deformation of moulding sands with hydrated sodium silicate and inorganic additives prepared in warm-box technology. Tested moulding sands were hardened in the temperature of 140oC for different time periods. Bending strength, thermal deformation and thermal degradation was tested. Chosen parameters were tested immediately after hardening and after 1h of cooling. Conducted research proved that it is possible to eliminate inorganic additives from moulding sands compositions. Moulding sands without additives have good enough strength properties and their economic and ecological character is improved.
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Abstrakt

The article takes into consideration the researches concerning inserting the Glassex additive to the microwaved-hardened and selfhardened moulding sands with water glass. In the research different types of ester hardeners to self-hardened moulding sands with water glass were used. The influence of Glassex additive on retained strength of moulding sands with different hardeners and prepared by different technologies of hardening were tested. The influence of different hardeners and the technology of hardening on retained strength of moulding sand with water glass and the Glassex additive were also estimated.
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