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Mechanical and Thermal Properties of Aluminum Foams Manufactured by Investment Casting Method

Dmitruk Anna, Kapłon H., Naplocha K.

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 1

37--42

EN

A method for the open-cell aluminum foams manufacturing by investment casting was presented. Among mechanical properties, compressive behaviour was investigated. The thermal performance of the fabricated foams used as heat transfer enhancers in the heat accumulator based on phase change material (paraffin) was studied during charging-discharging working cycles in terms of temperature distribution. The influence of the foam on the thermal conductivity of the system was examined, revealing a two-fold increase in comparison to the pure PCM. The proposed castings were subjected to cyclic stresses during PCM’s subsequent contraction and expansion, while any casting defects present in the structure may deteriorate their durability. The manufactured heat transfers enhancers were found suitable for up to several dozen of cycles. The applied solution helped to facilitate the heat transfer resulting in more homogeneous temperature distribution and reduction of the charging period’s duration.

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Cast Structures Improving Thermalm Conductivity for Energy Storage

Raźny Natalia M.

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 2

11--16

EN

Thermal energy encounters a huge demand in the world, part of which can be met by renewable energy sources, such as solar energy, and storage of thermal energy surplus from industrial processes. For this purpose, thermal energy storage (TES) units, in which heat is stored, are developed. The energy is accumulated by phase change materials (PCM) characterized by high phase transition enthalpy. PCMs have poor thermal conductivity; therefore, to take full advantage of their capabilities and to accelerate the charging and discharging cycle, metallic structures are used. These structures are manufactured using investment casting technology. Creating models with additive methods, such as 3D printing, allows obtaining complex shapes with high accuracy, such as thin-walled castings. At a large scale, the method may not be cost-effective. In this paper, the heat exchanger models were made from PLA and the castings - from AC44200 aluminum alloy. Investment casting requires the proper selection of parameters, such as the right material for the model, the selection of the firing temperature, the adjustment of the temperature of the molten metal, the temperature of the mold, and the pressure in it. Misaligning any of the parameters can lead to imperfections on the finished casting. Based on the model roughness study, it was found that minor roughness and higher accuracy are presented by the lower parts of the casting, while weaker performance is observed for the upper parts. Metal castings in a salt PCM environment may be subjected to corrosion. Therefore, the authors proposed to produce protective coatings on aluminum castings by the PEO method - plasma electrolytic oxidation. Porous ceramic thin films consisting mainly of alumina were obtained. The next tests will be aimed to confirm whether this layer will not negatively influence the thermal conductivity of the thermal energy storage.

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Influence of Mould Material on the Mechanical Properties of Wax Models

Kroma Arkadiusz, Brzęk P.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 3

48--52

EN

The article presents results of research on the influence of the mould material on selected mechanical properties of wax models used for production of casting in investment casting method. The main goal was to compare the strength and hardness of samples produced in various media in order to analyse the applicability of the 3D printing technology as an alternative method of producing wax injection dies. To make the wax injection dies, it was decided to use a milled steel and 3D printed inserts made using FDM (Fused Deposition Modeling) / FFF (Fused Filament Fabrication) technology from HIPS (High Impact Polystyrene) and ABS (Acrylonitrile Butadiene Styrene). A semi-automatic vertical reciprocating injection moulding machine was used to produce the wax samples made of Freeman Flakes Wax Mixture – Super Pink. During injection moulding process, the mould temperature was measured each time before and after moulding with a pyrometer. Then, the samples were subjected to a static tensile test and a hardness test. It was shown that the mould material influences the strength properties of the wax samples, but not their final hardness.

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5 Cs of Investment Casting Foundries in Rajkot Cluster – An Industrial Survey

Sata A. V., Maheta Nikunj R.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 3

102--108

EN

Investment casting is very well-known manufacturing process for producing relatively thin and multifarious industrial components with high dimensional tolerances as well as admirable surface finish. Investment casting process is further comprised of sub-processes including pattern making, shell making, dewaxing, shell backing, melting and pouring. These sub-processes are usually followed by heat treatment, finishing as well as testing & measurement of castings. Investment castings are employed in many industrial sectors including aerospace, automobile, bio-medical, chemical, defense, etc. Overall market size of investment castings in world is nearly 12.15 billion USD and growing at a rate of 2.8% every year. India is among the top five investment casting producer in the world, and produces nearly 4% (considering value of castings) of global market. Rajkot (home town of authors) is one of largest clusters of investment casting in India, and has nearly 175 investment casting foundries that is almost 30% of investment casting foundries of India. An industrial survey of nearly 25% of investment casting foundries of Rajkot cluster has been conducted in the year 2019-20 in order to get better insight related to 5 Cs (Capacity; Capability; Competency; Concerns; Challenges) of investment casting foundries located in the cluster. Specific set of questionnaires was design for the survey to address 5 Cs of investment casting foundries of Rajkot cluster, and their inputs were recorded during the in-person survey. The industrial survey yielded in providing better insight related to 5 Cs of foundries in Rajkot cluster. It will also help investment casting producer to identify the capabilities and quality issues as well as leads to benchmarking respective foundry.