Foundry Engineering

Rotary degassing is one of the most frequently used melt treatment technologies used for processing liquid aluminum alloys. Despite this, the information available about the possible effects of this method on the double oxide-and nitride film (bifilm) content, especially when using different purging gases, is quite limited. For this reason, in this study, the effects of multiple rotary degassing treatments conducted with N 2 and Ar purging gases on the bifilm quantity of a casting aluminum alloy were compared. The characterization of the melt quality was realized by the computed tomographic (CT) analysis of reduced pressure test (RPT) specimens, image analysis, and scanning electron microscopy (SEM) of the fracture surfaces of K-mold samples. Based on the results, by the application of Ar as a purging gas, relatively low bifilm content can be achieved. On the other hand, while the use of N 2 leads to the formation of numerous small-sized nitride bifilms, which significantly increased the pore number density inside the RPT specimens. This can be associated with the nitride formation by the chemical reaction between the liquid aluminum alloy and the N 2 purging gas bubbles during the degassing treatments.

The quality of chemically bonded sand cores used during the manufacturing process of cast components is highly dependent on the properties of the sand, which constitutes the refractory base media of the core. One of the main advantages of the application of different types of sands as molding aggregates that after casting, they can be reclaimed and can be used again during core shooting. The properties of the sand, however, could be remarkably changed during the casting and reclamation processes. This study aims to investigate the effects of the properties of the base sand on the mechanical strength and thermal distortion properties of samples made from new and thermally reclaimed silica sand. For this purpose, particle size analysis, specific surface area, and loss on ignition measurements, as well as differential thermal analysis coupled with thermogravimetry, were executed on the base sands, and the sand grains were analyzed with scanning electron microscopy and X-ray diffraction. Test pieces were made with hot box and cold box technology for bending and hot distortion tests. It was found that by the utilization of reclaimed sand, cores with higher average bending strength and lower thermal deformation can be produced. These differences can be traced back to the more advantageous granulometric properties, lower impurity content, and lower thermal expansion of thermally reclaimed sand.

The paper presents the analysis of technology of copper and alloyed copper destined for power engineering casts.
The casts quality was assessed based on microstructure, chemical content analysis and strength properties tests.
Characteristic deoxidising (Logas, Cup) and modifying (ODM2, Kupmod2) formulas were used for the copper where
high electrical conductivity was required. Chosen examples of alloyed copper with varied Cr and Zr content were
studied, and the optimal heat treatment parameters were tested for a chosen chromium copper content, based on
the criterion of hardness and electrical conductivity tests. Searching for materials with high wear resistance, the influence
of variable silicone content on the properties of CuNiSi alloy was researched.
Key words: copper, casting technology, refining alloy, microstructure, properties

Bimetallic casting adalah metode penggabungan dua material logam yang memiliki sifat mekanis maupun sifat fisik yang berbeda dengan metode pengecoran. Dua sifat logam yang tadinya sulit didapatkan dari satu jenis material kini dapat dimiliki dalam satu benda. Pada penelitian ini sifat keras pada Ni-Hard 4 dengan sifat lunak pada FCD digabungkan menjadi satu benda dengan dua lapis material tersebut. Metodenya adalah dengan mengecor outer material terlebih dahulu yaitu Ni-Hard 4. Setelah dibersihkan kemudian dituangkan material dalam (inner material) yaitu FCD dengan suhu interface pada percobaan yaitu sebesar 60%, 65%, 70%, dan 75% dari suhu penuangan FCD. Pada cetakan grinding roll dirancang sebuah kolam pemanas untuk mencapai suhu interface sebesar 60%, 65%, 70%, dan 75%, maka suhu interface pada material akan mencapai titik optimim dimana material Ni-Hard 4 dan FCD dapat mengikat melalui proses yang disebut diffusion bonding.

Investment casting technology belongs to the oldest casting techniques. Historically, it was used for casting tools, weapons and ornaments. A model, made from beeswax, was covered in loam, dried and fired. The casts obtained were characterised by high surface smoothness, accuracy and precision of its ornaments. This method was used for relatively small casts as well as for big monuments. Nowadays, this technology is used in many fields of manufacturing, both artistic and industrial, especially in armaments, aviation, automotive, power, construction and even space industry.
This work presents the results of research and experiments conducted in the field of casting technology of copper and copper alloys, applying the investment casting method, both in its historical aspect and modern industrial practice. An exemplary analysis was presented of the chosen elements of the old technologies, moulds and casts, as well as the results of casts made currently for the power industry. The casts quality was evaluated based on the research of their microstructure, chemical composition, electrical conductivity and oxygen content.

The research aimed at assessing the influence of alloying elements, such as Al, Si, Ni, Pb and Bi on the chosen alloys of Cu-Zn. Microstructures were examined with the use of optical and scanning microscopy with X-ray microanalysis. The properties of the received alloys were determined with regard to changes in the mechanical parameters, namely Rm, A5, HB, also, machinability changes were assessed as well as proclivity to hot fracturing of Cu-Zn alloys with additives of lead and bismuth. The results indicate the possibility of obtaining very high mechanical properties: Rm up to 700 MPa, hardness within the range of 130–180 HB and A5 from 3 to 30%. Also, in the case of the researched alloys, the machining and hot fracturing results look promising.
Keywords: Cu-Zn alloys, mechanical properties, technological properties, alloying additives

Metal Casting industry has a classic problem in handling the production process and quality control. Hybrid manufacturing and rapid prototyping are technological developments in the manufacturing sector that are currently attracting a lot of attention both within the industry and academics. Although there is no standard definition in hybrid manufacturing, this has become a lot of objects developed by researchers to find the influence of each combination of manufacturing processes carried out. Rapid prototyping in various cases shows the level of potential to reduce time and process in making a prototype. This paper is prepared to assess the potential and implications of hybrid manufacturing and rapid prototyping applications that are reviewed in the metal casting industry.

3D printer merupakan teknologi rapid prototyping yang telah berkembang pesat dalam decade ini. 3D printer menggunakan STL file yang berasal dari gambar 3D CAD sebagai input data untuk proses pengerjaan. Penelitian ini bertujuan untuk mengetahui pengaruh dari resolusi STL file yang digunakan terhadap kualitas geometri dan dimensi (G&D) dari produk yang dihasilkan. Penelitian ini dilakukan dengan menggunkaan 2 jenis resolusi STL file yang dibuat dengan Autodesk Inventor. Hasil penelitian memperoleh informasi bahwa terdapat pengaruh dari resolusi STL file yang digunakan terhadap kualitas geometeri dan dimensi produk yang dibuat. Pada kualitas geometeri produk memiliki perbedaan bentuk geometri pada bagian yang berbentuk radius. Sedangkan pada aspek dimensi produk diperoleh ketelitian dimensi produk 0.02-0.8 mm. Abstract Keywords: STL; 3D printer; casting pattern. 3D printer is a rapid prototyping technology that has developed rapidly in this decade. 3D printers use STL files derived from 3D CAD drawings as input data for the processing. The purpose of this study is to determine the effect of the resolution of the STL file used on the quality of the geometry and dimensions (G&D) of the product produced. This research was conducted by using 2 types of STL file resolution created with Autodesk Inventor. The results of this study are that there is an influence of the resolution of the STL file used on the quality of the geometry and dimensions of the product being made. the quality of the product geometry has different geometric shapes in the radius. Whereas in the aspect of the product dimension obtained a product dimension accuracy of 0.02-0.8 mm.

Una empresa que se instala o que desea aumentar su capacidad de producción debe analizar las diversas alternativas tecnológicas disponibles en el mercado actual, para la obtención de metal líquido. Esta evaluación debería hacerse con la mayor objetividad posible. Entran en consideración aspectos como la carga metálica, la disponibilidad y precio de coque y energía eléctrica, los consumos específicos y costos de los diversos consumibles, la capacidad y el ritmo de producción requeridos, los materiales a producir, las necesidades de mano de obra en cantidad y calidad, y los aspectos de seguridad y medio ambiente. Cada alternativa presenta determinadas ventajas y desventajas desde los puntos de vista técnico y económico. Mientras el horno de cubilote es una máquina de fundir de alta eficiencia térmica que acepta una gran variedad de materiales de carga y con los controles adecuados puede obtener un amplio espectro de composiciones químicas, requiere sin embargo un cierto nivel de inversión para evitar problemas ambientales. Los hornos de inducción presentan ventajas en cuanto a su versatilidad respecto a los materiales que es posible obtener, pero tienen ciertas restricciones en cuanto a la carga metálica y en cuanto al costo operativo, para cubas de gran capacidad. Los hornos eléctricos de arco, a su vez, presentan ventajas en cuanto a la adaptación a una variada gama de tipos de carga metálica pero utilizan electrodos de alto costo y presentan costos elevados para producciones pequeñas. Un análisis objetivo de todas las variables involucradas debería ser útil para conducir a una decisión técnica y económicamente acertada.

The presence of inclusions such as oxides, carbides or refractory particles can be harmful to the mechanical and surface characteristics of castings. Inclusion-rich metals result in lower fluidity and feeding capability during casting. Nowadays, solid fluxes are widely used in foundries in order to reduce the inclusion content of aluminium melts. In this study, the effect of four different fluxes on the melt quality was studied. First, the inclusion content of the flux-treated melt, and then the properties of the fluxes (i.e. chemical composition and melting temperature) were examined.

The analysis of brasses regarding their microstructure, mechanical properties and ecological characteristics has been
presented. The influence of characteristic alloying elements contained in the brasses and the possibilities of replacing them
with other elements have been assessed. The paper contains the results of studies on the influence of chosen additional elements shaping the structure and properties of unleaded alloys based on Cu-Zn system as the matrix. The research aimed at determining the mechanism and the intensity of influence of such additives as tellurium and bismuth. The microstructures were investigated with the help of light microscopy and scanning electron microscopy with X-ray microanalysis (SEM-EDS) for determining significant changes of the properties.

The research aimed at the comparison of the old and modern jewellery and goldsmith's articles, based on the alloys and technologies used. The jewellery was cast taking the historical artefacts as models, using the old traditions and technologies. The jewellery manufacturer of old, not only had to master the jewellery-making technologies including casting, but also he had to have the knowledge concerning his raw material. An important aspect of it were the metal working properties showing off the decorative and plastic scope of the material. That is why, for ornament production, alloys were used more often than pure metals, because they had better technological properties. It is an important aspect of work then, to get to know the technology of creating gold elements and comparing them with the methods used nowadays, and also preparing our own jewellery project and implementing it, with the help of both traditional and computer-aided modern technology. The inspiration and knowledge came mainly from the historical artefacts coming from excavations at the Market Square in Krakow; the finds were obtained through the cooperation of the Foundry Faculty of AGH, the University of Science and Technology with the Research Team for The Main Market in Krakow. This is both research as well as a creative project. It presents original projects, leading to actual manufacturing of a ring, with the help of traditional foundry technologies, including the lost-wax casting method. The chemical content was analysed with the help of X-ray fluorescence spectroscopy and macroscopic observations of chosen rings made from copper alloys. Also macroscopic observations of other artefacts were conducted. Historical patterns of ornaments, starting form the 11th century up to the present times, have become the source material about the 'old' jewellery making and the starting point for creating a 'new' collection. The work describes consecutive stages of creating a ceramic mould, and it can become the source material for information and research concerning the artistic craftsmanship field.

The presence of inclusions such as oxides, carbides or refractory particles can be harmful to the mechanical and surface characteristics of castings. Inclusion-rich metals result in lower fluidity and feeding capability during casting. Nowadays, solid fluxes are widely used in foundries in order to reduce the inclusion content of aluminium melts. In this study, the effect of four different fluxes on the melt quality was studied. First, the inclusion content of the flux-treated melt, and then the properties of the fluxes (i.e. chemical composition and melting temperature) were examined.

Soprattutto in quest’ultimo periodo la fonderia rappresenta nell’immaginario comune l’antitesi di qualsiasi tentativo di vivere nel rispetto dell’ambiente. Solo in poche occasioni però ci si rende conto di come sia solo grazie alle fonderie che l’uomo moderno riesca a conservare il suo elevatissimo standard di vita preservando l’ambiente stesso.

Per recuperare efficienza produttiva e vantaggi competitivi riducendo tempi e costi esistono diversi metodi e strumenti
standard di miglioramento d’affidabilità: la loro applicazione alle problematiche concrete di produzione in fonderia
riveste una sfida interessante da sostenere

Foundry sand is the main element of sand mixtures from which molds or sand cores are made. Due to the continuous development of coremaking technologies, the selection of the right type of base sand becomes more and more important. The major features of foundry sand are determined by the following factors: chemical and mineralogical composition, sand grain size, grain size distribution, sand grain shape, and surface quality. The main goal of our research was to develop a qualification method that can be used to predict the characteristics of sand cores made from different sand types. Samples made from different types of foundry sand were used during the research whose properties were examined with a new qualification system, and then its connection with the gas permeability of sand cores was analyzed. Based on the research results, a strong correlation could be established between the suggested quality indicators: CQi (Core Quality Index), CG (Coefficient of Granulometry), and permeability.

Entrained double oxide films, or bifilms, can seriously alter the structural integrity, microstructure, and in this way, the mechanical performance of aluminum alloys. Bifilms, which usually preexist in suspension in the liquid metals, are known to be potential heterogeneous nucleation sites for certain intermetallic phases during the solidification of the alloys. However, the investigations on the possibility of the nucleation of titanium-containing intermetallic phases on double oxide films, the possible effects of this phenomenon on the melt quality, as well as on the resulting microstructure, were absent to date. In this work, a novel melt treatment technique is proposed, which was used to induce the precipitation of (Al,Si)3Ti particles in a liquid multicomponent Alsingle bondSi alloy. Differential thermal analysis (DTA), scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) were used to characterize the phases formed during the experiment. SEM-EDS investigations proved that the (Al,Si)3Ti intermetallic phase precipitated on MgAl2O4 double oxide films and the wetted side of the surface oxide layer of the melt. As revealed by glow discharge optical emission spectroscopy (GDOES) and optical microscopic investigations of the microstructure, the majority of the precipitated (Al,Si)3Ti particles sedimented to the bottom region of the melt. Based on the computed tomographic (CT) analysis of reduced pressure test (RPT) samples, this sedimentation extensively reduced the bifilm content in the upper regions of the melt. The theoretical basis of a new melt treatment technique is laid down.

Nowadays, solid fluxes are widely used in foundries in order to reduce the inclusion content of alumínium alloy melts. The effect of fluxes is determined by their Chemical composition, morphology, added quantity, as well as the temperature of the melt and the method of flux addition. On the other hand, the reactions promoted by the flux can result in the increased oxidation rate of alloying elements which are prone to oxidation. Thus, the application of highly reactive fluxes in the case of Sr-treated melts can cause accelerated Sr-fading and inappropriate eutectic modification level. In this study, the effect of four different fluxes on the melt quality and Sr fading is described. First, the inclusion content and then, the Sr fading of the flux-treated metal was examined.

The article presents the research results obtained at the Department of Foundry of Non-Ferrous Metals at the Foundry Faculty of AGH, the University of Science and Technology, in Krakow. The research comprises the processes connected with the technology of melting, refining and making casts based on copper matrix, both contemporary and historical, especially bronzes containing tin, zinc and lead. These issues are well-known but they still pose problems for contemporary foundries. The article presents the results of modifying formulas on the improvement of mechanical properties and limiting casting defects.
Keywords: copper, bronze, refining, modification

The entrainment of the surface oxide layer of aluminum alloy melts is currently a mostly inevitable process during the melt handling and processing techniques of the foundry industry. As a consequence, a large number of double oxide films (bifilms) are often incorporated into the melts, which bifilms can act as initiation sites for pore formation during the solidification of the alloy. In this study, this relationship between bifilms and pores was examined in the case of an Al-Si-Mg-Cu based alloy. The entrained oxide film content of the melts was characterized by the analysis of the fracture surfaces of K-mold specimens, Bifilm-Index measurement and X-ray computed tomography (CT) of reduced pressure test (RPT) samples, which can be considered as a new method of melt quality characterization. It was found that the number of oxide films found on the fracture surfaces of K-mold specimens is proportional to the number density of pores found in RPT samples. Investigations with scanning electron microscopy (SEM) revealed that oxide films can be found on the inner surface of the pores in RPT samples, which confirms the theory, that pores and bifilms are interconnected phenomenon. Based on the results, the bifilm content and so the quality of aluminum melts can be characterized using CT analysis of RPT samples.

Conoscere l’affidabilità dei propri impianti, come e quando un certo dispositivo smetterà prevedibilmente di lavorare, in che modo interagisce con gli altri, quanto tempo occorre per
ripristinarne il corretto funzionamento, quando costa un intervento e quali disfunzioni nascono in caso di rottura improvvisa sono le informazioni di fatto indispensabili per
realizzare un valido piano di manutenzione con criteri ottimizzati verso la massima convenienza: ecco alcuni strumeti per riuscirci

ABSTRAK Industri Pengecoran Logam memiliki masalah klasik dalam menangani proses produksi dan penjaminan kualitas. Penelitian ini memberikan solusi untuk memecahkan masalah industri pengecoran logam dengan memperkenalkan dan menerapkan 3D printer dengan sistem fused deposit material. Teknologi ini digunakan untuk mengefektifkan proses produksi pola cor. Proses pembuatan pola cor biasanya mengambil 70% dari keseluruhan waktu produksi sebuah produk cor. Tujuan dari penelitian ini adalah mengkaji penerapan pembuatan pola cor dengan 3D printer dengan sistem fused deposit material. Metode penelitian yang dilakukan adalah (1) penggambaran 3D CAD pola cor, (2) konversi ke format STL, (3) 3D printer setup, (4) proses print, (5) analisis, (6) kesimpulan. Hasil yang diperoleh adalah 3D printer dengan sistem fused deposit material dapat digunakan untuk melakukan pembuatan pola cor. Dari analisis ketelitian pola cor dengan 3D printer memiliki selisih ukuran berkisar 0,2mm. Sedangkan untuk analisis kualitas geometri, hasil pola cor dari 3D printer dengan sistem fused deposit material memiliki bentuk yang baik tetapi kurang pada hasil permukaannya. Dengan demikian 3D printer dengan sistem fused deposit material layak digunakan untuk pembuatan pola cor karena memiliki ketelitian yang cenderung konsisten dan kemudahan dalam pembuatan pola cor. Hal ini membuka peluang untuk pengembangan lanjutan untuk 3D printer pada sektor industri pengecoran logam. ABSTRACT Metal Casting Industry has a classic problem in handling the production process and quality assurance. This research aims to provide solutions to solve the problems of the metal casting industry by introducing and applying 3D printers with a fused deposit material system. This technology is used to streamline the production process of cast patterns. The process of making a casting pattern usually takes 70% of the total production time of a cast product. The purpose of this study is to examine the application of making cast patterns with a 3D printer with a fused deposit material system. The research methods carried out are (1) create of 3D CAD cast patterns, (2) conversion to STL format, (3) 3D printer setup, (4) printing process, (5) analysis, (6) conclusions. The results obtained are a 3D printer with a fused deposit material system that can be used to make cast patterns. From the analysis of the accuracy of the cast pattern with the 3D printer has a difference in size ranging from 0.2 mm. As for the analysis of the quality of the geometry, the results of the cast pattern of the 3D printer with the fused deposit material system have a good shape but lack results on the surface. Thus a 3D printer with a fused deposit material system is suitable for making cast patterns because it has a consistent tendency and ease in making cast patterns. This opens up opportunities for continued development of 3D printers in the metal casting industry sector.

Rotary degassing is one of the most frequently used melt treatment technologies used for processing liquid aluminum alloys. Despite this, the information available about the possible effects of this method on the double oxide- and nitride film (bifilm) content, especially when using different purging gases, is quite limited. For this reason, in this study, the effects of multiple rotary degassing treatments conducted with N2 and Ar purging gases on the bifilm quantity of a casting aluminum alloy were compared. The characterization of the melt quality was realized by the computed tomographic (CT) analysis of reduced pressure test (RPT) specimens, image analysis, and scanning electron microscopy (SEM) of the fracture surfaces of K-mold samples. Based on the results, by the application of Ar as a purging gas, relatively low bifilm content can be achieved. On the other hand, while the use of N2 leads to the formation of numerous small-sized nitride bifilms, which significantly increased...

The development of the industrial revolution 4.0 will certainly be a new problem in The Ceper Metal Casting Industry if it is not accompanied by technological developments. This research has an important goal which is to be reference data for determining policies to government, to provide protection and support the metal casting industry players. Interviews and questionnaires become a method to collect this data and there were 110 respondents. The method to process the data used SPSS 18 and Excel. 30 respondents from outside the sample have been tested for validity and reliability. The results are reliable, 76.5 ≥ 0.5. The data showed that 47.3% of respondents thought that their human resources ready to faced industrial revolution 4.0. And then, 50.9% of respondents assumed that the metal casting industry still used manual systems in the manufacturing process. Therefore the conclusion is that industrial revolution 4.0 has not yet been fully implemented in the metal casting industry because the technology used still manual and not yet automatic.

An attempt to examine the earliest traces of non-ferrous metal metallurgy and casting in present-day Krakow has been made. The preparatory investigation has centred around a group of finds coming from a small section of the eastern part of the city, the area of Nowa Huta. The paper gives an overall view of objects ranging from the first copper artefacts from the territory of Poland in the 4th millennium BC through Lusatian bronzes and Celtic products to modern slag from Jan Thurzo’s copper smelter. The analysis, involving diverse copper or copper alloy artefacts, ornaments and tools – both imports and local products – has been aimed at preliminary identification of Krakow’s earliest metal artefacts in terms of their materials and methods of production, and at preparing the ground for further study. This multifaceted research is intended to result in a comparison of materials and techniques used in metallurgy and casting during the timespan of 5000 years.
Keywords: archaeometallurgy, casting of non-ferrous metals, copper, bronze, brass

The article focused on researching the influence of Ti, B, Sr and Na as a modifying treatment elements for Al-Si alloys.
The influence of alloying additives such as Cu and Cr was studied. Tensile strength Rm, elongation A5 and HB hardness
was analysed, as well as the influence of the above-mentioned elements on the microstructure and solidification
of alloys containing a varied content of Si, within the 7 ÷ 16 % range. The influence of heat treatment on the
alloy properties was also researched.
Keywords: aluminium alloys, casting technologies, heat treatment, innovative materials, modification

64 l'opinione Primo comandamento: "Proteggi la vita" La sicurezza dell'ambiente di lavoro è un aspetto estremamente complesso, per le diverse sfaccettature che assume quando si passa dai concetti più generali per calarsi nella concretezza delle diverse realtà produttive. Nel nostro Paese, come negli altri dell'Occidente industrializzato, almeno a parole e nelle dichiarazioni di principio (che è già qualcosa: duemila anni non sono passati invano) nessuno mette in dubbio la necessità di porre al centro dell'attenzione il rispetto per la persona, la salvaguardia della sua incolumità e, per quanto possibile, la creazione di ambienti di lavoro a misura d'uomo.

Prezentowany felieton jest jednym z dłuższego cyklu felietonów, publikowanych w Gazecie Myślenickiej w tym celu, żeby zachęcić do tworzenia w tym mieście innowacyjnych firm, bazujących na wiedzy naukowej i technicznej powstającej w nieodległym Krakowie. W tym felietonie wskazywane są możliwości związane z czerpaniem wiedzy z Wydziału Odlewniczego AGH. Podane są argumenty, dlaczego produkcja oparta na odlewnictwie może znajdować nabywców powstających wyrobów.

In order to produce cast components, which meet the quality requirements of the automotive and aerospace industries, the control of liquid metal quality prior to the casting process is essential. Rotary degassing is the most commonly used melt treatment method in the foundry industry, which can effectively reduce the inclusion and solute hydrogen content of the metal. This procedure is often combined with fluxing, which allows more efficient inclusion removal during melt processing. In this study, the effects of rotary degassing treatments executed with and without flux addition on the melt cleanliness were compared. The quality of the molten metal was characterized by the microscopic inspection of K-mold specimens, X-ray computed tomography of reduced pressure test samples, and by Density-Index evaluation. The inclusions found on the fracture surfaces of K-mold samples were analyzed with energy-dispersive X-ray spectroscopy. Based on the results, rotary degassing coupled with flux addition can be an effective inclusion and solute hydrogen removal technique that can significantly improve melt quality. On the other hand, rotary degassing executed without flux addition can increase the inclusion content of the melts. This can be attributed to the chemical reaction between the liquid alloy and the N 2 purging gas during the degassing process. It was also found that inclusion content highly influences the tendency to porosity formation.

ln this study, the effects of different melt cleaning fluxes on the inclusion content and tensile properties of an aluminum casting alloy were compared. Melt treatments, consisting of rotary degassing with N2 gas, and flux addition were executed using four different fluxes. The inclusion content of the melts was investigated with the evaluation of K-mold samples. ln order to get information about the impact of the differences of melt quality on the mechanical properties of final products, cylindrical tensile specimens were machined from heat-treated castings and tensile tests were carried out. The fracture surfaces of tensile specimens and K-mold samples were inspected with stereomicroscope and scanning electron microscope.

QUANDO SI PARLA DI RIPARAZIONE DEI GETTI, IN GENERE, SI APRE SEMPRE UN DIBATTITO SULLA SUA AMMISSIBILITÀ O MENO. IL
RAGGIUNGIMENTO DELLA PERFEZIONE RAPPRESENTA SEMPRE, INDUBBIAMENTE, L’OTIMUM AL FINE DELL’OTTENIMENTO DI UN
PRODOTTO CONFORME, MA PURTROPPO SI SA, IN FONDERIA,
IN FASE DI FABBRICAZIONE, SPESSO CAPITA DI INCORRERE IN
PROBLEMATICHE NON PREVEDIBILI CHE POSSONO CREARE QUALCHE
PROBLEMA AL PRODOTTO CON UN CONSEGUENTE AUMENTO
DEI COSTI DI SCARTO. OGGI LA RIPARAZIONE DEI GETTI FORNISCE
UNA STRADA ALTERNATIVA.

È idea comune, quanto errata, che le tecnologie fusorie si siano sviluppate progressivamente e riadattate lentamente per rispondere alla necessità sempre più raffinate dell'uomo moderno. Al contrario, molto spesso sono gli sbalzi tecnologici ad aver condizionato l'evoluzione umana, indirizzandola su percorsi nuovi, imprevisti persino pochissimi anni prima. Questo è quanto è accaduto quando, per esempio, si dimostrò come per produrre l'acciaio il carbon coke andasse altrettanto bene, se non meglio, del carbone di legna, e lo sfruttamento delle foreste cessò: cominciò allora il predominio del carbone come fonte di energia, durato poi per più di un secolo. Ma anche l'avvento dell'altoforno, all'inizio apparso alla stregua di un esperimento mal riuscito o poco più, ha aperto invece la strada alla produzione di acciaio in quantità industriali e alla società così come la conosciamo. Ai nostri giorni la sensazione comune è che il mondo della fonderia, considerato a livello globale, stia vivendo un momento che potremmo definire di "dinamica attesa" con una lunga serie di interessantissime tecnologie lì alle porte, nessuna delle quali sembra però riuscire a prendere il via con slancio. Titanio, magnesio e vanadio hanno dimostrato da tempo la loro superiorità in moltissime applicazioni, senza tuttavia mai riuscire a diventare competitive su larga scala. Le schiume di alluminio appaiono una soluzione avveniristica e rivoluzionaria, ma restano per ora soltanto una curiosità. Infine i compositi a matrice metallica sono da tempo allo studio e però non sono mai stati utilizzati se si eccettuano alcune applicazioni di nicchia. Mentre nel frattempo, con una evoluzione lenta e continua, le ghise rafforzano il loro predominio sul mondo. È la storia stessa che però esorta le fonderie a mantenere alta l'attenzione nei confronti di tutte le tecnologie che sono appunto alla porta, come si è detto. perché, lo si è visto, basta un cambiamento tecnologico quasi impercettibile per modificare di colpo il futuro della metallurgia. E resta evidente come ogni cambiamento futuro debba tenere conto delle esigenze sempre più stringenti dell'eco-sostenibilità. Questo aspetto è tanto più vero per una nazione sui generis come la nostra, nella quale la mancanza cronica di un piano energetico degno di un tale nome rende più cara l'energia e porta i nostri costi a essere superiori per oltre il 6% rispetto a quelli dei principali concorrenti europei. Senza questa barriera le esportazioni potrebbero godere di un aumento stimato attorno o oltre i 10 punti percentuali, rafforzando la nostra immagine di competitor mondiale. Ma l'ambiente non è solo energia: molte delle fonderie italiane sono di fatto inserite in piccoli e grandi contesti urbani. Talvolta sono le stesse industrie fusorie, posizionate all'interno dei complessi industriali, ad aver attirato i lavoratori e le loro famiglie fino a costituire il nucleo di nuovi agglomerati cittadini. L'ecologia è diventata quindi un valore sociale, oltre che economico, su cui è necessario basare il prossimo salto tecnologico.