The automotive industry is one of the most important customers for the foundry industry. In particular, casting of engine parts for combustion engines is one of the most demanding areas of casting technology. New generation of engine blocks and cylinder heads are getting geometrically more complicated in order to maintain or even increase performance. With the increased complexity, the strain for the casting molds is growing and the widely used technology of core making with standard silica sands is, for several applications, no longer reaching the demanded results. Furthermore, in last decade, there has been an effort in using inorganic binders in core making process, which brings along some additional technological challenges. In order to cope with these challenges, in this paper, silica and non-silica sands with round and angular grains as well as with fine and coarse grains are examined using an inorganic binder for strength, permeability, and thermal stability. The results shall provide useful information about the possibilities of application and combining different types of foundry sands, both silica and non-silica. With their impact on the selected sand core properties, they can help in solving problems in the core making process as well as reaching a high quality of the final product-casting.
Quality of machine production is very close-knit with quality of metallurgical semi-products and with improvement their working properties. It can be achieved first of all by decrease of sulphur and non-metallic inclusions content in metal. Improvement of working properties provide remelted processes above an electro slag remelting (ESR). The slags play very important role by ESR process. By experiments steel with next chemical composition was used: C (0,9 – 1,1%), Mn (0,30 – 0,50%), Si (0,15 – 0,35%), Cr (1,30 – 1,65%), Ni (max.0,30%), Cu (max.0,25%), P (max.0,027%), S (max.0,030%). The steel was remelted under 8 types of slags on the base of CaO, Al2O3, CaF2 and SiO2 in different ratios. The contribution deals with influence of chemical composition of slag on mechanical properties and cleannes of metal after electro slag remelting. Variation of slag chemical composition enables to change chemical composition of remelted steel, to reduce the non-metallic inclusions and sulphur content and to improve the mechanical properties of steel.
The solidification of cast iron is a complex process with characterized entrance and marginal conditions. Thermal analysis is one of the processes that allows us to observe the solidification of alloys. There is a possibility of gaining information about the melted cast iron quality and predicting the final properties of the cast by evaluating the scanned cooling curves by solidification (stable and metastable system). This article deals with the study and analysis of cooling curves taken from production conditions of a foundry during ductile cast iron production. The aim is to discover the reproduction and reliability of the thermal analysis results of cast iron. The study of the progress of the cooling curves and their first derivation to follow the reactions of the curves to changing factors in the production process.
Fluidity is the basic foundry property. The fluidity of AlSi alloy in real condition with computer simulation were compared. In this test was used two types of molds: horizontal molds with tree canals and vertical molds with six canals wich had different diameter (4,5; 6,5; 8,5; 10,5; 12 and 14 mm). As experimental material was used AlSi10MgMn (EN 1706) alloy. Range of pouring temperature was between 605°C to 830°C. NovaFlow&Solid soft commercial software package was used for numerically simulating the fluid flow of molten metal. The model of fluidity test was created by CAD system CATIA V5 R19. Measurement systems analysis (MSA), the analysis of the variance (ANOVA), t-test and the analysis of correlation were used for the evaluation. Youden plot was used for evaluation of the impact of operators on the errors. Values of fluidity for each temperature level obtained by the horizontal mold have a high degree of agreement with those obtained by computer simulation. On the contrary, the values, obtained by the vertical mold are more sensitive to the operator. This fact caused the match between the simulation and a practical experiment is only partial.
Ductile iron is a high-carbon-containing iron-based alloy in which the carbon, as graphite, is present in a spheroidal shape. With its good mechanical properties, ductile iron approximates the properties of steel and the cost per unit of strength compared to other materials. With suitable metallurgical treatments, we can influence its microstructure and resulting properties. Incorrect manufacturing technology and metallurgical processes give rise to casting defects and decreased mechanical properties. The contribution is devoted to measures to prevent the occurrence of defects in the casting of rope drums and to achieve the required mechanical properties of these castings. The most-common defects in these castings are micro-shrinkages in casting heat centers and unsatisfactory mechanical properties such as tensile strength, yield strength, and elongation.
Article deals with problematice of influencing mechanical properties -tensile strength and hardness -of grey cast iron by heat treatment -refinement. Refinement could be in special cases applied also for grey cast iron castings in order to achieve special parameters of hardness and tensile strength of parts for specific purposes. Hardening and tempering of casting sis commonly used for ductile cast iron, but in special cases could be applied also for grey cast iron castings. Refinement -hardening and tempering -was provided on samples from materiál EN GJL 150, EN GJL 200 and EN GJL 250. Afterwards, measured values of tensile strength, hardness and fractography of materiál in poured state and after tempering on temperatures 250, 350 and 450°C after quenching from austenitization temperature 920°C were compared. Achieved results are formulated in the evaluation part of article.
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