scholarly journals Influence of additives in core-forming mixture

2017 ◽  
Vol 62 (1) ◽  
pp. 335-338
Author(s):  
I. Vasková ◽  
M. Hrubovčáková ◽  
M. Conev

Abstract In recent years, ingredients, also known as additives, which appreciably affect the quality of the casting surface, come to the fore. Additives - lower the temperature at which SiO2 (major component of silica sand) begins to soften and create a melt on the surface of the grains, increase the reactivity and decrease the temperature of a transition to tridimite and cristobalit. These passages support the increase of volume of subsurface sand stress and the tension for the formation of burrs and other casting defects on the surface of the core or the mold. Nowadays, as a great emphasis is put on the quality of the casts, it is therefore necessary to pay attention to these additives, which can effectively reduce the labor intensity in the production of castings and ensure a quality surface of castings.

2018 ◽  
pp. 36-40
Author(s):  
kinga Boroń

This article discusses the issues concerning the quality of casting surface with a small unit weight manufactured on the Disamatic automatic casting lines in a flaskless mould with a vertical parting line. The research was conducted in manufacturing conditions in one of the casting facilities in the country. The identification of casting defects for a monthly manufacturing cycle was made and agreed that the main causes of scrap casting are defects on the raw surface: lumps of moulding sand which after removal form cavities and draws as well as defects of gas origin such as blowholes. There are also defects of form namely short runs. In the later part of the work, the research results of the properties of moulding sand were presented and casting defects were selected the occurrence of which is connected with the quality of moulding sands.


2013 ◽  
Vol 58 (3) ◽  
pp. 853-857
Author(s):  
M. Holtzer ◽  
A. Bobrowski ◽  
D. Drożyński ◽  
J. Mocek

Abstract High-manganese cast steels are characterised by a high abrasion resistance under friction conditions with a simultaneous influence of pressure and impacts. This cast steel is especially suitable for castings of excavator’s scoops, track links, streetcars crossovers, parts of crushers and mills for braking up of hard materials [1-4]. In order to obtain high quality castings of high-manganese cast steels in moulds on the high-silica sand matrices it is necessary to apply protective coatings, which prevent a direct contact between metal and matrix (SiO2). Manganese after being poured into a mould can undergo a partial oxidation forming MnO, which reacts with silica. As a result low-melting manganese silicates are formed, which in a form of a tight layer adhere to the casting surface, significantly increasing a labour input related to cleaning. Three kinds of protective coatings were tested: zirconium, corundum and magnesite. As a base moulding sands on high-silica sand matrices with three kinds of resol resins were applied. The quality of the obtained casting surface was assessed in dependence of the protective coating and resin kind and also in dependence of the metallostatic pressure value.


2011 ◽  
Vol 121-126 ◽  
pp. 4269-4273
Author(s):  
Ping Ai ◽  
Bo Zhao

In CAID software based on NURBS technology, the quality of curve directly affects the quality of surface, and the post-editing and modification of the surface, so good curve is the core and key to build high-quality surface. In this paper, combining the basic theory of NURBS curves with practical experience, we conduct an in-depth study in the method of controlling the quality of the NURBS curves, and propose an implementation to improve the quality of the NURBS curves.


Author(s):  
Mark Oprenko

The definition of the multimorbidity concept reveals insufficient specificity of the comorbidity and multimorbidity definitions and, as a result, confusion in the use of these terms. Most authors are unanimous that the “core” of multimorbidity is presence of more than one disease in a patient. These coexisting diseases can be pathogenetically interconnected and non-interconnected. Regardless, the degree of multimorbidity always affects prognosis and quality of life.


Edupedia ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 45-53
Author(s):  
Ilzam Dhaifi

The world has been surprised by the emergence of a COVID 19 pandemic, was born in China, and widespread to various countries in the world. In Indonesia, the government issued several policies to break the COVID 19 pandemic chain, which also triggered some pro-cons in the midst of society. One of the policies government takes is the closure of learning access directly at school and moving the learning process from physical class to a virtual classroom or known as online learning. In the economic sector also affects the parents’ financial ability to provide sufficient funds to support the implementation of distance learning applied by the government. The implications of the distance education policy are of course the quality of learning, including the subjects of Islamic religious education, which is essentially aimed at planting knowledge, skills, and religious consciousness to form the character of the students. Online education must certainly be precise, in order to provide equal education services to all students, prepare teachers to master the technology, and seek the core learning of Islamic religious education can still be done well.


Author(s):  
Juan Alfredo Lino-Gamiño ◽  
Carlos Méndez-González ◽  
Eduardo José Salazar-Araujo ◽  
Pablo Adrián Magaña-Sánchez

In the value chain it is important to keep in mind the core business of the company, since it depends largely on the competitiveness of the company and its overall performance, bearing in mind that all business indicators depend on it. In this work we will study the washing process within the company WASH CONTAINERS SA DE CV, to improve the washing processes and in this way reduce times and movements in the process leading the company to reduce costs considerably within the operations company daily, having a more competitive operation and with greater profit margin in its business process. Goals: It Improve the logistics of the movement of containers for washing and with it the core business of the company. Methodology: The action research will be applied applying Business Process Management for the improvement of processes in situ, it will be developed in a certain period of time and with that it will establish an improvement projection. Contribution: The improvement of the times for the disposal of the containers and their subsequent use, allows a better competitiveness and with it the income of the company, on the other hand, the transport companies improve in performance in quantity, quality of disposition and with it their income.


Author(s):  
Patrícia Rossini ◽  
Jennifer Stromer-Galley

Political conversation is at the heart of democratic societies, and it is an important precursor of political engagement. As society has become intertwined with the communication infrastructure of the Internet, we need to understand its uses and the implications of those uses for democracy. This chapter provides an overview of the core topics of scholarly concern around online citizen deliberation, focusing on three key areas of research: the standards of quality of communication and the normative stance on citizen deliberation online; the impact and importance of digital platforms in structuring political talk; and the differences between formal and informal political talk spaces. After providing a critical review of these three major areas of research, we outline directions for future research on online citizen deliberation.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Bakhe Nleya ◽  
Philani Khumalo ◽  
Andrew Mutsvangwa

AbstractHeterogeneous IoT-enabled networks generally accommodate both jitter tolerant and intolerant traffic. Optical Burst Switched (OBS) backbone networks handle the resultant volumes of such traffic by transmitting it in huge size chunks called bursts. Because of the lack of or limited buffering capabilities within the core network, burst contentions may frequently occur and thus affect overall supportable quality of service (QoS). Burst contention(s) in the core network is generally characterized by frequent burst losses as well as differential delays especially when traffic levels surge. Burst contention can be resolved in the core network by way of partial buffering using fiber delay lines (FDLs), wavelength conversion using wavelength converters (WCs) or deflection routing. In this paper, we assume that burst contention is resolved by way of deflecting contending bursts to other less congested paths even though this may lead to differential delays incurred by bursts as they traverse the network. This will contribute to undesirable jitter that may ultimately compromise overall QoS. Noting that jitter is mostly caused by deflection routing which itself is a result of poor wavelength and routing assigning, the paper proposes a controlled deflection routing (CDR) and wavelength assignment based scheme that allows the deflection of bursts to alternate paths only after controller buffer preset thresholds are surpassed. In this way, bursts (or burst fragments) intended for a common destination are always most likely to be routed on the same or least cost path end-to-end. We describe the scheme as well as compare its performance to other existing approaches. Overall, both analytical and simulation results show that the proposed scheme does lower both congestion (on deflection routes) as well as jitter, thus also improving throughput as well as avoiding congestion on deflection paths.


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