laboratory researches upon the thermal fatigue of the organs of machines in movement of rotation, in variable temperature mediums

The researches of durability in the exploitation of cast-iron rolls define experimentally an important chapter from the thermal fatigue of the organs of machines in the movement of rotation, in variable temperature mediums. The researches on the durability in exploitation of hot rolling mill rolls represent an important scientific and economical issue. This paper presents original experimental equipment by the help of which the durability of hot rolling mills can be studied. This experimental equipment permits the evaluation of exploitation durability for hot rolls by studying the thermal fatigue phenomenon which appears in the case of machine components. The exploitation durability is evaluated through thermal fatigue cycles up to crack point due to thermal fatigue for each condition and each type of studied material. The study represents a detailed approach of the influence of various technological factors on the durability in exploitation of rolling mill rolls made of different steel and pig iron grades and suggests solutions meant to increase the durability of the rolls in exploitation

Constructive Improvements in the In-Ladle Treatments - A Comparative Industrial Study

Nodular gray cast iron having properties superior to conventional gray cast iron can be produced by treating the molten iron so that, when cast, the graphite will be compacted rather than in flake form. One such treatment involves the introduction of magnesium (Mg) into a molten iron bath of such composition. It is the principal object of the present industrial experiments to provide an improved process for the ductile cast iron production. Another object is to provide a process which permits the efficient use of the nodulizing agents, which results in the efficient production of an improved homogeneous nodular cast iron. Essentially such treatments result in the retention by the cast iron of small amounts of nodulizing agents, for example magnesium (Mg). Conventionally these agents are added to cast iron, usually in the form of pre-alloys and the efficiency of the process is illustrated by the high assimilation of the added nodulizer’s constituents. Another object of this technological practice is to provide an improved method for introducing the nodulizing agents, using constructive improvements to the in-ladle equipment. Finding magnesium (Mg) using novel techniques is the first step to advance the understanding of the role of magnesium (Mg) in the formation of the nodular graphite, the mechanism behind nodular graphite formation due to the addition of Magnesium (Mg) being still relative unclear at present time. Moreover, this may advance new methods to improve the nodulizing treatment process. This study take into account the flexibility of the used technique, which describes the elasticity of the treatment process, by improvement or alternative to the existing one. As nodulizing agents magnesium-ferrosilicon (Fe-Si-Mg type) and cerium-magnesium-ferrosilicon (Nodulin type) are examples of materials containing nodulizing agents that have given excellent results in the mixture. This experiments relates to a process for the production of ductile iron (nodular gray cast iron) and particularly to a process for adding magnesium (Mg) to the melted iron

Comparative Study on the In-Ladle Treatment Techniques for Nodulizing the Iron’s Graphite

The objectives of this research is to study and understand the nodulizing of ductile iron using in-ladle treatment process. Among the more common nodulizing agents is magnesium (Mg) which is conventionally added to the cast iron by combining suitable alloys of one or both of these elements with molten cast iron. Depending on the characteristics of each master alloy used as nodulizer, different treatment methods and techniques are used, among these, the most widely used being in-ladle, in-mould, and flow-through, the first being the most used. This research deals with the parameters, that affect the quality of ductile iron produced using in-ladle treatment process. The parameters involved are the percentage of magnesium–ferrosilicon (Fe–Si–Mg) used and the nodulizing technique. In-ladle treatment used consists of a deep pocket into the bottom of ladle, in which magnesium–ferrosilicon is placed into it together with a steel scrap barrier (steel sheets) or calcium carbide. This study, take into account, the degree of assimilation of magnesium, which shows the performance of the chosen process, depending on the nodulizer used and the temperature of the treatment

Eksperimentalno istraživanje trajnosti u eksploataciji valjaoničkih valjaka

The purpose of this work is to present some guidelines in the quality improvement of rolling iron rolls, aiming at increasing durability and safety in operation. The study analyses the influence of chemical composition on durability in exploitation of rolling mill rolls. The research also suggests solutions meant to increase the rolling mill rolls endurance in exploitation. The research on durability in exploitation of rolling mill rolls represents an important scientific and economical issue. These researches are trying to give answers to most actual problems related to the increase of hardness of rolling mill rolls. They are characterized by a complex system of cracking of the superficial caliber layer or they simply break because of the thermal shocks caused by the contact of the hot metal with the water-cooled rolls. The research uses data collected from the industrial use at the Iron and Steel Laboratory of the Faculty of Engineering - Hunedoara as well as laboratory experiments carried out on an unique, complex and original installation. In this sense, the paper presents some results of a series of researches and experimentations of durability on testing lots through laboratory experiment, in distinct series, that represent the object of the laboratory research methodology. Although the manufacture of rolls is in constant improvement, the requirements for superior quality rolls have not yet been met, in many cases the absence of quality rolls preventing the realization of quality laminates or the realization of productivities of which rolling mills are capable. In this sense, durability in exploitation is extremely important both for immediate practice and for the scientific research attributed to the cast-iron rolls.Namjera ovog rada je predstaviti neke pravce vezane za poboljšanje kvalitete željeznih valjaoničkih valjaka, s ciljem povećanja trajnosti i sigurnosti u radu. Studija predstavlja detaljnu procjenu utjecaja kemijskog sastava na trajnost u eksploataciji valjaoničkih valjaka. Također, istraživanje sugerira rješenja kojima je cilj povećati izdržljivost valjaoničkih valjaka u eksploataciji. Istraživanje trajnosti u eksploataciji valjaoničkih valjaka predstavlja važan znanstveni i ekonomski problem. Ova istraživanja pokušavaju dati odgovore na većinu stvarnih problema vezanih za povećanje tvrdoće valjaoničkih valjaka. Oni su karakterizirani složenim sustavom pojave pukotina na površinskom sloju ili jednostavnim lomom, uslijed toplinskog šoka prouzročenog kontaktom vrelog metala s vodom hlađenim valjcima. Istraživanje koristi podatke prikupljene iz industrijske uporabe na Iron and Steel Laboratory of the Faculty of Engineering - Hunedoara, kao i laboratorijskim eksperimentima provedenim na jedinstvenoj, kompleksnoj i originalnoj instalaciji. U tom smislu, namjera rada je predstaviti neke rezultate niza istraživanja i ispitivanja trajnosti na ispitnim kockama, kroz laboratorijske eksperimente, u posebnim serijama, koje predstavljaju predmet metodologije laboratorijskog istraživanja. Proizvodnja valjaka se stalno usavršava, no zahtjevi za vrhunsku kvalitetu još uvijek nisu u potpunosti zadovoljni. U većini slučajeva, nedostatak kvalitetnih valjaka sprečava ostvarenje kvalitetnih ploča ili produktivnosti valjaonica za koju su predviđene. U tom smislu, trajnost u eksploataciji je vrlo aktualna, kako za neposrednu praksu, tako i za znanstvena istraživanja koja se odnose na valjke od lijevanog željeza

About the numerous cost and processing advantages of the microcellular foam injection molding process for thermoplastics materials in the automobile industry

Today one of the goals of the automobile industry is to reduce weight. And physical foaming has already demonstrated its potential in this sector, improving the value and performance of applications under the bonnet: engine and gearbox cases, inlet air filters, cockpits, radiator baffles and so on. Around the world, the microcellular injection molding (MuCell) is used in thousands of applications in the automotive, packaging, technical molding, office machinery and electric and electronic component industries. The research opportunities purpose is to obtain even lighter pieces, with greater dimensional stability and with an excellent surface finish, in other words, perfect plastic parts. More component functionality with reduced weight, and cost control at the same time: MuCell is a process to physically foam thermoplastics, which combines technical and economic objectives. Besides weight reduction, it also provides improved dimensional stability of the moulded parts

About the numerous cost and processing advantages of the microcellular foam injection molding process for thermoplastics materials in the automobile industry

Today one of the goals of the automobile industry is to reduce weight. And physical foaming has already demonstrated its potential in this sector, improving the value and performance of applications under the bonnet: engine and gearbox cases, inlet air filters, cockpits, radiator baffles and so on. Around the world, the microcellular injection molding (MuCell) is used in thousands of applications in the automotive, packaging, technical molding, office machinery and electric and electronic component industries. The research opportunities purpose is to obtain even lighter pieces, with greater dimensional stability and with an excellent surface finish, in other words, perfect plastic parts. More component functionality with reduced weight, and cost control at the same time: MuCell is a process to physically foam thermoplastics, which combines technical and economic objectives. Besides weight reduction, it also provides improved dimensional stability of the moulded parts

Ecological restoration activities for long-term preservation of the alpine and sub-alpine habitats in the Retezat National Park

This paper is focusing on the mountain pines (Pinus mugo), the juniper (Juniperus communis) and the rhododendron (Rhododendron kotschyi) common habitats, the establishing the methods of maintaining or protecting of non-degraded populations, and the restoration methods of degraded populations, within the alpine habitats conservative management belonging to the Retezat National Park.. Between the natural and artificial regeneration methods applicable to restore the degraded mountain pines populations, the regeneration by plantation seems to be the only reasonable method, having in view that the natural regeneration is difficult and require long period of time. This study begins with presentation of the preservation plans of the unique natural landscape, named Retezat National Park, located in Meridional Carpathians (Romanian Southern Carpathians) and continues with the description of the natural distribution of the mountain pines (Pinus mugo) populations and their associated herbaceous and woody species in the Retezat National Park. The renaturation with mountain pines seedlings, within the case study regarding an ecological restoration in Retezat National Park, methods, remarks and predictable results are presented. Also, the study offers details concerning the ecological principles of the destroyed habitat’s artificial regeneration, such as: the planted area, seedlings, seedling production and their transportation to the planting area and effective plantation

Bimetallic cast iron rolls – Some approaches to assure the exploitation properties

U ovom se radu detaljno razmatra utjecaj nekih tehnoloških faktora na trajnost valjaoničkih željeznih valjaka i predlažu rješenja za povećanje izdržljivosti u uporabi. Istraživanjem se pokušavaju dati odgovori na najvažnije probleme u vezi povećanja tvrdoće valjaka. Dobiveni rezultati su od neposredne praktične koristi kako za proizvođačku industriju valjaoničkih valjaka od lijevanog željeza tako i za valjaoničke odjele. U tom se smislu ovi rezultati mogu koristiti u ljevaonicama i valjaonicama za osiguranje kvalitete valjaka sve od faze proizvodnje pa do uporabe, što neizbježno vodi do osiguranja kvalitete proizvedenih laminata. Analiziraju se stvarni tehnički uvjeti lijevanja kako bi se povećala otpornost valjaka na trošenje, smanjili troškovi konverzije i reducirao otpad, smanjili radni troškovi smanjivanjem bogato legiranog željeza s potrošnjom nikla, kroma i molibdena. Korištenjem nove metode istraživanja – numeričke simulacije – obradili su se statistički i matematički podaci zabilježeni kada se elaborirao željezni lijev tipa FDId2 namijenjen lijevanju tvrde kore bimetalnih valjaka velikog promjera. Svrha je optimizirati kemijski sastav kao faktor od utjecaja na tvrdoću valjaka, a tako implicitno i na njihova uporabna svojstva. Postizanje optimalnog kemijskog sastava može predstavljati tehnički efikasan način za osiguranje uporabnih svojstava budući da materijal valjaka ima u tom smislu važnu ulogu. Primijenjena je matematička metoda počevši od diferenciranja sastavnih dijelova valjaka, uzimajući u obzir industrijske podatke dobivene u ljevaonici valjaka, kao i specifikacije nacionalnog standarda koji preporučuje tvrdoću kod različitih kemijskih sastava. U tom smislu ovo istraživanje može pridonijeti optimiziranju industrijskih tehnologija analizom i matematičkim eksperimentom.The study represents a detailed approach of the influence of some technological factors on durability in exploitation of rolling mill iron rolls and suggests solutions meant to increase the durability of the rolls in exploitation. These researches are trying to give answers to most of the actual problems related to the increase of hardness of rolling mill rolls. These results are of immediate practical utility both for the cast-iron rolling mills roll manufacturing industry and the rolling sectors. In this sense, these research results can be used in the collective framework of the foundries and the rolling mills sectors for quality assurance of rolls as far back as the phase of production to their exploitation, what leads to, inevitably, the quality assurance of produced laminates. Genuine casting technical conditions are analyzed in order to increase the rolls\u27 resistance to wearing, decrease the conversion costs and reduce the waste, decrease the labor costs by lowering the richly alloyed iron with nickel, chromium and molybdenum consumption. Using the new research technique – the numerical simulation – statistical and mathematical data, registered when elaborating the cast iron type FDId2 destined to cast the hard crust of the large-diameter bimetallic rolls, were processed within the present research. The purpose is the optimization of the chemical composition as an influential factor on the rolls hardness, thus, implicitly, on their exploiting qualities. The realization of an optimal chemical composition can constitute a technically efficient mode to assure the exploitation properties, the rolling mills rolls material having an important role in this sense. From this point of view the mathematical modeling is applied, starting from the differentiation on rolls component parts, taking into consideration the industrial data obtained in rolls-foundry, as well as the national standard specifications, which recommend the hardness for different chemical compositions. From this point of view the research is inscribed in the context of scientific capitalization of the process and the industrial technologies optimization, in the way of the analysis and the mathematical experiment

Complaint Analysis Using 8D Method within the Companies in the Field of Automotive

The eight disciplines (8D – Eight Disciplines of Problem Solving) model is a problem solving approach typically employed by quality engineers or other professionals and commonly used by the automotive industry. It is a meticulous process used to solve complex problems and its purpose is to identify, correct, and eliminate recurring problems, and it is useful in product and process improvement. The 8D is a method of analysis that after the detection of an irregularity, identifies and seeks the methods of solving and preventing nonconformity. It is a highly disciplined and effective scientific approach for resolving recurring problems and provides excellent guidelines to identify the root cause of the problem, implement containment actions, develop and then implement corrective actions and preventive actions that make the problem go away permanently. Therefore, the Eight Disciplines of Problem Solving (8D) is a problem-solving tool used usually in response to the removal parameters or known product specifications set by customers and incorporates all the important aspects of problem solving: problem description, root cause analysis, correcting the problem and preventing the problem. The approach establishes a permanent corrective action based on statistical analysis of the problem and focuses on the origin of the problem by determining its root causes. Although it originally comprised eight stages, or disciplines, it was later augmented by an initial planning stage. The 8D method application will result in improved products and processes is structured into eight disciplines, focusing on the synergy of the team. This is a popular method for problem solving because it is reasonably easy to teach and effective

Complaint analysis using 8D method within the companies in the filed of automotive

The eight disciplines (8D – Eight Disciplines of Problem Solving) model is a problem solving approach typically employed by quality engineers or other professionals and commonly used by the automotive industry. It is a meticulous process used to solve complex problems and its purpose is to identify, correct, and eliminate recurring problems, and it is useful in product and process improvement. The 8D is a method of analysis that after the detection of an irregularity, identifies and seeks the methods of solving and preventing nonconformity. It is a highly disciplined and effective scientific approach for resolving recurring problems and provides excellent guidelines to identify the root cause of the problem, implement containment actions, develop and then implement corrective actions and preventive actions that make the problem go away permanently. Therefore, the Eight Disciplines of Problem Solving (8D) is a problem-solving tool used usually in response to the removal parameters or known product specifications set by customers and incorporates all the important aspects of problem solving: problem description, root cause analysis, correcting the problem and preventing the problem. The approach establishes a permanent corrective action based on statistical analysis of the problem and focuses on the origin of the problem by determining its root causes. Although it originally comprised eight stages, or disciplines, it was later augmented by an initial planning stage. The 8D method application will result in improved products and processes is structured into eight disciplines, focusing on the synergy of the team. This is a popular method for problem solving because it is reasonably easy to teach and effective