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Quality Prediction in Vertical Centrifugal Casting Using Criterion Function
Published in Om Prakash Jena, Sudhansu Shekhar Patra, Mrutyunjaya Panda, Zdzislaw Polkowski, S. Balamurugan, Industrial Transformation, 2022
The centrifugal casting process involves pouring the molten metal at a proper temperature into revolving mould and then allowing it to solidify. Centrifugal casting is less difficult than other gravity poured castings because there are neither unconnected gates nor risers. Centrifugal casting process is most widely employed for production of pipes, cylinders, liner brake drums, flywheel and other parts. Vertical centrifugal casting is commonly used for cylindrical shapes where aspect ratio (ratio of diameter to height) is in the range of 1–3. Typical vertical centrifugal casting experimental setup is shown in Figure 10.1. Industrial castings of ASTM A413 (LM6) and ASTM A356 (LM25) manufactured by vertical centrifugal casting process are widely used in several industrial sectors including chemical, food and marine. These industrial castings often face quality issues related to occurrence of defects such as porosity, blow holes, pin holes, hard spots, etc. Occurrence of porosity is mainly due to variations in either solidification or filling related process parameters. Presence of shrinkage porosity in castings is shown in Figure 10.2.
Physical and Mechanical Properties of Recycled Metal Matrix Composites
Published in R.A. Ilyas, S.M. Sapuan, Emin Bayraktar, Recycling of Plastics, Metals, and Their Composites, 2021
Pradeepkumar Krishnan, Ramanathan Arunachalam
Recycling of MMCs can be carried out using the vacuum centrifugal casting method. The centrifugal casting process is a casting technique used to manufacture thin-walled cylinders by pouring molten metal into a rapidly spinning cylindrical mold. The centrifugal rotational force exerts pressure on the molten metal. Under the Ar gas atmosphere, waste master alloys are heated to a molten state. After the alloy is melted, the chamber lids are closed, and a pump evacuates the vacuum chamber. The melt is kept under vacuum conditions to extract the gases dissolved in the melting alloy. This method will prevent harmful material oxidation. The melt is then preheated. The die oriented on the horizontal axis is selected according to the desired component shape. The centrifugal force serves to disperse molten metal in the mold at pressures reaching several times the force of gravity. The centrifugal force effect can be determined through the following equation: G=2DN2, where D is the diameter of the casting tube and N is the rate of revolution. Yamagiwa et al. produced a functionally graded material (FGM) by the centrifugal process using Al and Fe wastes (Yamagiwa et al., 2003). This process is illustrated graphically in Figure 8.5.
Advances in Fabrication of Functionally Graded Materials
Published in T. S. Srivatsan, T. S. Sudarshan, K. Manigandan, Manufacturing Techniques for Materials, 2018
In this process, the reinforcement phase is poured into a molten metal to make a homogeneous mixture. The required gradation of material properties is attained using proper segregation of reinforcement particles through gravitational or centrifugal forces (Saiyathibrahim et al. 2015). There are two different categories of centrifugal casting methods, which are based on the difference between reinforcement particle temperatures and processing temperature. If the processing temperature is higher than the reinforcement particle temperature, then this technique is known as a centrifugal in situ technique and centrifugal forces can be used during the solidification step. Alternatively, if the reinforcement particle is subjected to a higher temperature than the processing temperature, the second phase remains solid in the molten metal, and this is known as the centrifugal solid-particle technique (Naebe and Shirvanimoghaddam 2016; Watanabe et al. 2006). The FGMs obtained from these methods reflect high wear resistance and bulk toughness. The primary advantage of the centrifugal casting method is it improves the density of the metal, increases the actual mechanical properties of the casting by 10% to 15%, and provides a uniform metallurgical structure (Gupta and Talha 2015).
Study on three-body abrasive wear behavior of functionally graded Al/TiB2 composite using response surface methodology
Published in Particulate Science and Technology, 2018
An advanced and innovative type of materials evolved from the particle reinforced aluminum composites for further improvising the wear resistance of the aluminum composites is the functionally graded materials (FGMs). This material has continuous variations in its microstructure, composition, and distinct properties within a single part (Song, Xu, and Li 2007). FGMs are mostly useful in the applications where high wear resistance combined with toughness is necessity (Vieira et al. 2009). Researchers found that centrifugal casting is an economic and easy way for fabricating the FGM and has several advantages such as good control in composition under centrifugal force and better mold filling characteristics (Shimaa Hadad et al. 2010). Functionally graded aluminum/SiC and aluminum/Al2O3 composites have been fabricated through centrifugal casting, and their mechanical properties are investigated. The results show that the outer region of both the FGMs has more reinforcement concentration due to the action of centrifugal force, and this region shows better mechanical properties (Rodriguez-Castro, Wetherhold, and Kelestemur 2002; Thirtha Prasad and Chikkanna 2011). An attempt has been made to fabricate pistons by incorporating SiC particles through centrifugal casting, and 70% reduction in wear rate was found compared to pistons fabricated through gravity permanent mold casting (Huang et al. 2011).
Analysis of Factor Effects in Process of Vertical Centrifugal Casting
Published in Materials and Manufacturing Processes, 2023
K. Jurković, H. Cajner, P. Mrvar, B. Bauer
In vertical centrifugal casting, a cylindrical mold is rotated around its vertical axis while molten metal is poured into the mold cavity. This rotational motion creates a centrifugal force that directs the molten metal to the inner walls of the mold, resulting in uniform distribution of the material.[1,2]Compared to typical casting methods such as gravity casting, the centrifugal force significantly reduces casting defects such as shrinkage porosity and promotes a finer grain structure throughout the casting. Furthermore, considering the time required to produce castings, vertical centrifugal casting process proves to be economically justified, making it a cost – effective choice.[3–5]
Performance analysis of centrifugal-cast single-point cutting-tools developed from scrapped tools
Published in Materials and Manufacturing Processes, 2022
Shubhashree Mohapatra, Hrushikesh Sarangi, Upendra Kumar Mohanty
Centrifugal casting, also known as ‘liquid forging’, includes pouring the melt of appropriate composition into a rotating mold that continues to rotate till the completion of solidification of the poured melt. This necessarily means the casting is produced experiences the centrifugal force which presses the melt against the mold wall which imparts compactness, a casting with dense structure with ample scope for the voids, porosities, any air-pockets, etc., to get eliminated and in some cases, get welded with the help of centrifugal force. During casting, the dense relatively cold melt is forced toward the mold-surface, i.e., the outer surface of the casting by the resultant centrifugal force, while the hotter melt with relatively low viscosity at the interior, provides for metal feeding. Thus, a directionality in solidification is achieved which counters the formation of solidification shrinkages and results in a dense and compact casting.[5] The lighter inclusions and impurities in the melt get segregated toward the central portions of the casting and can be easily separated from the casting by machining operations. The included gases in the melt get precipitated at an accelerated rate. The resultant casting is relatively clean and acquires high metallurgical quality, with a true metallic continuity. As a consequence of the outward movement of the denser, relatively cold metal, in addition to the fact that the casting outer surface is already at lower temperatures due to the effects of the ambience, the interior of the casting is maintained at higher temperature for a longer time.[6,7] This high- to low-temperature gradient manifests itself in a gradation of the mechanical and microstructural properties. The higher rate of nucleation at the outer surface generates a fine grained structure, accounting for a hardened cast structure.[8] Simultaneously the interior, being at high temperature for a longer time, experiences a higher rate of grain growth accounting for a relatively coarse grain structure that imparts ductility and toughness to the casting.[5,9] Therefore, in tune with the requirements envisaged for a cutting tool, there is a gradation of properties, from a hardened outer to a toughened inner surface, in the casting.