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The Effect of Reclaim Primary Quality on Moulding Sand Parameters and Quality of Ductile Iron Casting Surface Layer

Kamińska Jadwiga, Angrecki M., Puzio S., Stachowicz M.

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 2

83--88

EN

The aim of the research was to determine the effect of the primary quality of reclaim from dry mechanical reclamation on the strength properties and service life of moulding sands based on this reclaim. Another aim was to establish the effect of the quality of reclaim, sulphur content - in particular, on the surface quality and thickness of the deformed surface layer in ductile iron castings. The research has revealed differences in the strength parameters and service life (mouldability) of sands based on the tested reclaims, depending on the type of the furfuryl resin used, including resins whose synthesis was done as part of the Żywfur project. Examinations of the structure of the surface layer of test castings poured in moulds made of loose self-hardening sands containing the addition of reclaim have confirmed the occurrence of degenerated spheroidal graphite in this part of the casting. It should be noted here that when massive castings with a long solidification time are made, the graphite degeneration effect can be more visible and the layer with the changed structure can increase in thickness. The research has clearly shown that it is necessary to control the parameters of the reclaim, including sulphur content which is transferred from the hardener and accumulates on the grains. This phenomenon has a negative impact not only on the sand strength and technological properties but also on the surface layer of castings.

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Żywice furfurylowe (furanowe)

Wróbel Janusz

Przegląd Odlewnictwa

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2019

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Vol. 69, nr 1-2

18--25

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Preliminary Tests of Innovative Eco-Friendly Furfuryl Resins and Foundry Sand Mixtures Based on These Resins

Kamińska Jadwiga, Puzio Sabina, Angrecki Michał, Stachowicz Mateusz, Łoś Anna

Journal of Ecological Engineering

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2019

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Vol. 20, nr 9

285--292

EN

The foundry industry in Poland and EU member states is growing steadily. The alloys based on ferrous metals (cast steel and cast iron) largely contribute to this upward trend. Currently, foundries are facing the problem of increasing requirements, which enforce the production of castings characterized by high dimensional accuracy and surface smoothness with parallel elimination of casting defects. Castings are mostly made in moulding sand mixtures, which are also subject to more and more stringent requirements to meet the above-mentioned casting acceptance conditions. Additionally, moulding sands should ensure adequate mould stiffness to avoid the risk of dimensional deformations during the pouring of liquid metal to this mould and casting solidification. For these reasons, the production of this type of castings has been dominated by loose self-hardening sands with furfuryl resin, commonly called furan sands. In the group of self-hardening sands with synthetic resins, loose self-hardening sands with furfuryl resin enjoy the greatest popularity. What accounts for this fact is the high level of the reclamability of these sands, the possibility of obtaining castings with high dimensional accuracy, the ability to make intricate moulds and cores, the binding process taking place at ambient temperature, and low content of binder. Unfortunately, this technology also has some disadvantages, which include short lifetime of the sand mixture, harmful gases emitted from the sand, and currently also high cost of the sand mixture. The anticipated tightening of the environmental protection regulations in the EU countries, including limiting the content of free furfuryl alcohol in resins (<25% by mass) and reducing the emission of furfuryl alcohol, formaldehyde and BTEX compounds at workplaces, necessitated the development of a new generation of furfuryl resins friendly to the environment. The article compares the results of testing the strength properties of foundry moulding sands using two types of resins, i.e. the resin of a new generation synthesized by Grupa Azoty JRCh and a commercial resin used in the foundry industry. Additionally, derivatographic studies of the above mentioned sand mixtures were conducted, and the loss on ignition and the amount of gases emitted by the sand mixture were determined. Melting was also carried out to study the impact of the resin used on the surface quality of iron castings.

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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.

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Effect of Mechanical Reclamation Cycle on Strength Parameters of Loose Self-Hardening Sands Based on Furfuryl Resin

Kamińska J., Basińska E., Angrecki M., Palma A.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 4

1843--1846

EN

The results of mechanical reclamation of waste moulding sands with furfuryl resin and activators of new generation are presented. The aim of the research described in this study was to determine what effect the addition of reclaim obtained in the process of dry mechanical reclamation could have on the properties of furan sands. The sand supplied by one of the domestic foundries was after the initial reclamation subjected to a two-step proper reclamation process. The following tests were carried out on the obtained reclaim: pH, S and N content, loss on ignition and comprehensive sieve analysis. The obtained reclaim was next used as a component of moulding sands with furfuryl resin, wherein it formed 50% and 80% of the base moulding material, respectively. The strength properties of the ready sand mixtures (bending strength Rgu and tensile strength Rm u ) were determined after the hardening time of 0.5, 1, 2, 4 and 24 hours.

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Influence of the Reclaim Addition into the Matrix on the Hardening Process Kinetics of the Moulding Sand with Furfuryl Resin

Jamrozowicz Ł., Kolczyk J., Wojtuń P.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

41--46

EN

Measurements of the hardening process course of the selected self-hardening moulding sands with the reclaimed material additions to the matrix, are presented in the hereby paper. Moulding sands were produced on the „Szczakowa” sand (of the Sibelco Company) as the matrix of the main fraction FG 0,40/0,32/0,20, while the reclaim was added to it in amounts of 20, 50 and 70%. Regeneration was performed with a horizontal mechanical regenerator capacity of 10 t/h. In addition, two moulding sands, one on the fresh sand matrix another on the reclaimed matrix, were prepared for comparison. Highly-fluid urea-furfuryl resin was used as a binder, while paratoluensulphonic acid as a hardener. During investigations the hardening process course was determined, it means the wave velocity change in time: cL = f(t). The hardening process kinetics was also assessed (dClx/dt = f(t)). Investigations were carried out on the research stand for ultrasound tests. In addition strength tests were performed.

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Technology of manufacturing foundry cores using additive methods

Matysik P., Drożyński D., Olszowska-Sobieraj B., Grzegorek J., Bubrowski P.

Metallurgy and Foundry Engineering

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2017

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Vol. 43, no. 3

189--198

EN

The use of additive manufacturing methods for the production of sand cores with organic binders is currently the latest trend in small and unit production, as it allows for a quick and simple way to get a final cast part; this is known as Rapid Prototyping. In this article, manufactured additive method cores were analyzed that were made of quartz sand with furfuryl resin and cores made of synthetic sand. Derivatographic measurements were compared, and examples of the high complexity cores are shown. Furthermore, the aspect ratio of the grains was determined by microscopic observation. Each type of core was characterized by a different flexural strength and differentiated results of abrasion. The results were collected and compared.

PL

Wykorzystanie przyrostowych technik zwanych „szybkim prototypowaniem” do produkcji rdzeni z mas ze spoiwami organicznymi jest obecnie najnowszym trendem w produkcji małoseryjnej i jednostkowej. Techniki te umożliwiają otrzymanie gotowego wyrobu w bardzo szybki i prosty sposób. W niniejszym artykule przeanalizowano wytworzone metodą addytywną rdzenie z piasku kwarcowego ze spoiwem furfurylowym oraz rdzenie z piasku syntetycznego ze spoiwem syntetycznym, porównano wyniki pomiarów derywatograficznych oraz pokazano przykładowe rdzenie o dużym stopniu skomplikowania. Ponadto na podstawie obserwacji mikroskopowych wyznaczono współczynnik kształtu ziaren. Każdy typ rdzenia charakteryzował się inną wytrzymałością na zginanie oraz zróżnicowanymi wynikami ścieralności. Wyniki zostały zebrane i porównane.

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The thermal and structural analysis of new bicomponent binders for moulding sands consisting of furfuryl resin and polycaprolactone (PCL)

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

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 1

369--372

EN

The aim of the article is thermal and structural analysis of new two-component binders for foundry moulding sands. The previous research showed the possibility of using biodegradable materials as binders or parts of binders’ compositions for foundry moulding and core sands. This paper is concentrated on estimating the influence of PCL on phenol-furfuryl resin thermal destruction (measured by derivatographic research) and its structure (measured by FTiR technology). The research proved that addition of new biodegradable additive PCL in the amount of 5-15% to the phenol-furfuryl resin doesn’t change the resin thermal destruction course but it results in appearance of a new band in two-component binder structure. What’s more there has been noticed a growth of intensity for band at wavenumber 1730 cm-1 (C = O) with the increasing addition of PCL.

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Wpływ dodatku materiału biodegradowalnego jako komponentu dwuskładnikowego spoiwa odlewniczych mas formierskich i rdzeniowych na właściwości spoiwa oraz mas z jego zastosowaniem

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

Prace Instytutu Odlewnictwa

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2016

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Vol. 56, no. 4

391--399

PL

Rosnące wymagania dotyczące emisji substancji szkodliwych zmuszają przemysł odlewniczy do poszukiwania nowych, bardziej przyjaznych dla środowiska rozwiązań. Do rozwiązań takich mogą należeć: technologie sporządzania mas formierskich i rdzeniowych z zastosowaniem organicznych materiałów biodegradowalnych jako spoiw. Należy jednak pamiętać, że nowe technologie muszą zapewnić wysokie właściwości technologiczne mas formierskich i rdzeniowych. W niniejszym artykule przedstawiono wyniki badań nowych dwuskładnikowych spoiw formierskich, w których część powszechnie stosowanej w praktyce odlewniczej żywicy fenolowo-furfurylowej zastąpiono materiałem biodegradowalnym w postaci polikaprolaktonu (PCL). W artykule przedstawiono badania wpływu materiału biodegradowalnego jako komponentu nowego dwuskładnikowego spoiwa na degradację termiczną spoiwa, jego lepkość oraz na wybrane właściwości technologiczne badanych mas z zastosowaniem nowego spoiwa, w tym ich deformację cieplną oraz elastyczność w temperaturze otoczenia. Przeprowadzone badania wykazały, że zastąpienie w spoiwie części żywicy fenolowo-furfurylowej materiałem biodegradowalnym PCL nie wpływa na degradację termiczną nowego spoiwa, zwiększa natomiast jego lepkość. Masy z zastosowaniem dwuskładnikowego spoiwa charakteryzują się zbliżonymi właściwościami technologicznymi do mas zawierających tylko żywicą fenolowo-furfurylową.

EN

The increasing requirements concerning the emission of hazardous substances force the casting industry to search for new, more environment-friendly solutions. Such solutions may include technologies of developing moulding and core sands with the use of organic biodegradable materials as binders. We should, however, remember that the new technologies must ensure high technological properties of the moulding and core sands. This article presents the results of investigations of new binary moulding binders, where part of the phenol-furfuryl resin commonly applied in casting, was replaced by a biodegradable material in the form of polycaprolactone (PCL). The article discusses the investigations of the effect of the biodegradable material as a component of a new binary binder on the thermal degradation of the binder, its viscosity as well as the selected technological properties of the examined moulding sands, including their thermal deformation and elasticity at ambient temperature. The performed examinations showed that replacing a part of the phenol- furfuryl resin in the binder with the PCL biodegradable material does not affect the thermal degradation of the new binder, while increasing its viscosity. The moulding mixtures with the applied binary binder are characterized by similar technological properties to the moulding sands with the phenol-furfuryl resin only.

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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.

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Comparison of the Emission of Aromatic Hydrocarbons from Moulding Sands with Furfural Resin with the Low Content of Furfuryl Alcohol and Different Activators

Żymankowska-Kumon S., Bobrowski A., Grabowska B.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

187--190

EN

No-bake process refers to the use of chemical binders to bond the moulding sand. Sand is moved to the mould fill station in preparation for filling of the mould. A mixer is used to blend the sand with the chemical binder and activator. As the sand exits the mixer, the binder begins the chemical process of hardening. This paper presents the results of decomposition of the moulding sands with modified urea-furfuryl resin (with the low content of furfuryl alcohol below 25 % and different activators: organic and inorganic) on a quartz matrix, under semi-industrial conditions. Investigations of the gases emission in the test foundry plant were executed according to the method extended in the Faculty of Foundry Engineering (AGH University of Science and Technology). Article presents the results of the emitted chosen aromatic hydrocarbons and loss on ignition compared with the different activators used to harden this resin. On the bases of the data, it is possible to determine the content of the emitted dangerous substances from the moulding sand according to the content of loss on ignition.

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Nowe żywice furfurylowe bardziej przyjazne dla środowiska

Holtzer M., Kmita A., Roczniak A.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 4 spec.

47--50

PL

Coraz ostrzejsze przepisy w zakresie ochrony środowiska wymuszają na producentach materiałów dla przemysłu odlewniczego opracowywanie nowych produktów, bardziej przyjaznych dla środowiska. Jednym z takich produktów są żywice furfurylowe, które obecnie mają największy udział w grupie mas no-bake. Wprowadzone w ostatnich latach w UE przepisy dotyczące ograniczenia zawartości wolnego alkoholu furfurylowego (< 25%) w żywicach oraz naciski w kierunku redukcji emisji SO2, formaldehydu, fenolu, benzenu i toluenu, jak również związków z grupy WWA, szczególnie na stanowiskach pracy spowodowały pojawienie się na rynku nowej generacji żywic furfurylowch oraz katalizatorów (o zmniejszonej zawartości siarki lub bezsiarkowych). W artykule dokonano analizy wpływu tych nowych produktów stosowanych w technologii mas z żywicami furfurylowymi na środowisko i warunki pracy.

EN

More and more strict regulations, concerning the environment protection, force the producers of materials for foundry industry to develop new products, more friendly for the environment. One of such products are furfuryl resins, which currently have the largest share within the group of no-bake moulding sands. Regulations introduced in the last years in the European Union concerning limitations of a free furfuryl alcohol content (< 25%) in resins as well as pressures to reduce SO2, formaldehyde, phenol, benzene, toluene and compounds from the PAHs group emissions, especially at work stands, caused an appearance of the new generation of furfuryl resins and catalysts (of a decreased sulphur content or even sulphur-free). The analysis of the influence of these new products, applied in the moulding sands with furfuryl resins technology, on the environment and work conditions was performed in the hereby paper.

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Właściwości energetyczne pyłów z regeneracji mechanicznej mas z żywicami furfurylowymi w aspekcie ich utylizacji termicznej

Holtzer M., Dańko R.

Przegląd Odlewnictwa

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2013

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Vol. 63, nr 5-6

188--194

PL

Samoutwardzalne masy formierskie SMS (no-bace) z żywicami furfurylowymi stanowią obecnie największy udział w produkcji odlewów ze stopów żelaza. Jakość odlewów produkowanych w masach tego typu jest wysoka, technologia w znacznym stopniu uniwersalna, zarówno pod względem stosowanego stopu odlewniczego (żeliwo, staliwo) oraz wielkości i stopnia skomplikowania odlewu.