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1

Rapid tooling in sand casting applications

100%

Dolinsek S. , Kopac J. , Brtoncelj G. , Kosic P.

Archives of Materials Science

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2007

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tom Vol. 28, nr 1-4

30-34

EN

Rapid tooling refers to process and technologies that help shorten time from planning to producing tools and with which the production costs are reduced. Classic technological procedures, such as turning, milling or casting are still the most common way of producing products from a wide range of available materials; rapid tooling is an option how to make those procedures faster, cheaper and better. On the example of the casting model we present the analysis of time and costs savings between separate procedures of rapid tooling according to classic production of casting application with high-speed cutting.

2

Effect of High-tin Bronze Composition on Physical, Mechanical, and Acoustic Properties of Gamelan Materials

84%

Slamet S. , Suyitno S. , Kusumaningtyas I. , Miasa I. M.

Archives of Foundry Engineering

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2021

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tom Vol. 21, iss. 1

137--145

EN

High tin bronze alloy (Cu>17wt.%Sn) is commonly as raw material to fabricate musical instruments. Gamelan musical instruments in Indonesia are produced using tin bronze alloy raw materials. The tin bronze alloy used by each gamelan craftsman has a different tin composition, generally in the range of Cu(20-24) wt.% Sn. This study aims to investigate the effect of microstructure, density, and mechanical properties of Cu(20-24)wt.%Sn against the acoustic properties processed by the sand casting method. The material is melted in a crucible furnace until it reaches a pouring temperature of 1100ºC by the sand casting method. The specimens were subjected to microstructure observations, density and porosity as well as mechanical properties testing including tensile strength, bending strength, hardness, and modulus of elasticity. Mechanical properties data then used to calculate several parameters of acoustic properties including speed of sound (c), impedance (z) and radiation coefficient (R). Processes simulation using Finite Element Analysis (FEA) and Experiment Method Analysis (EMA) were carried out to determine acoustic properties including sound intensity, natural frequency and damping capacity. The experimental result shows that the increase in tin composition in Cu(20-24) wt.% Sn changed the microstructure of coarse grains into dendrite-columned fine grains. Physical properties of density decrease, while porosity increases. Mechanical properties including tensile strength, modulus of elasticity, and bending strength decreased, while the hardness of the alloy increases. The calculation of acoustic parameters such as the speed of sound (c), impedance (z) and radiation coefficient (R) has decreased. Moreover, sound intensity (dB), natural frequency (Hz) and damping capacity also decrease with increasing tin composition. Hence, tin bronze alloy Cu20wt.%Sn is the recommended raw material for the manufacture of gamelan instruments through the sand casting method.

3

Metal head-dependent HTC in sand casting simulation of aluminium alloys

84%

Cellini G. S. , Tomesani L.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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tom Vol. 29, nr 1

47-52

EN

Purpose: In order to obtain reliable sand casting products, it is essential that the temperature distribution within the alloy during cooling is accurately known at each point by FEM simulation. This requires a great precision in setting the Heat Transfer Coefficients (HTC) at the boundaries. In particular for castings of big size, chills are frequently at different heights, so that remarkable differences arise from the metal head effect. Design/methodology/approach: An A356 alloy was cast and cooled. The castings were mono-directionally solidified in a experimental equipment modified to accept a controlled variable metal-head. HTC were evaluated in a side arm, where a chill end ensured a dominant unidirectional heat flow during cooling. At the end of a square horizontal channel, an aluminium chill of the same section and 60 mm in depth determined nearly one-dimensional cooling conditions. Findings: The evolution of heat transfer coefficient (HTC) in the sand casting of A357 aluminum alloy against aluminum chills is evaluated with different metal heads in order to study the effect of pressure on the HTC. Inverse modeling techniques based on Beck's analysis were used to determine the experimental evolution of HTC as a function of time, casting temperature and chill temperature. The HTC evolution at the casting-chill boundary is then described as a function of local parameters such as casting-chill interface pressure (as long as they are in contact) and interface gap (when solidification shrinkage occurs and the casting detaches from the chill). Practical implications: Finally, the experiments are reconstructed by means of coupled thermal-stress numerical analyses and the predicted cooling curves are fitted to the experimental ones by adjusting model parameters. As a result, the best parameters for describing the HTC evolution are found, thus allowing to extrapolate any possible HTC behavior on chills at different heights for the same casting. Originality/value: Some transient interface pressure can develop between casting and chill, the effect being negligible in HTC evaluation with the aim to precisely predict the cooling evolution inside the casting.

4

A Study of Inclusions in Aluminum and Titanium Deoxidized 4130

84%

Tuttle R. B. , Kottala S.

Archives of Foundry Engineering

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2018

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tom Vol. 18, iss. 1

129--134

EN

In this paper, the authors investigated the size distribution of titanium oxide (TiO2), titanium nitride (TiN) and titanium carbide (TiC) inclusions in a titanium deoxidized 4130 steel and compared it with the 4130 base alloy composition inclusions. TiN and TiC inclusions are of particular interest due to their role as heterogeneous nuclei for various phase reactions in steels. Two types of samples were prepared, a polished sample and a filtered sample. Electrolytic dissolution was employed to make the filter paper samples. The size range of titanium inclusions was found to be more than that of the non-metallic inclusions from 4130 base alloy heat. Titanium inclusions from the filter and polished samples were round in shape. TiC and TiN inclusions were not found in the electrolytic extraction samples. Inclusions and their chemistries were analyzed using scanning electron microscope and energy dispersive spectrometer. The inclusion size range was larger for the titanium deoxidized samples than the base alloy. However, in both steels the majority of inclusions had a size smaller than 10 μm.

5

Effect of Post Cast Heat Treatment on Cu20wt.%Sn on Microstructure and Mechanical Properties

84%

Slamet S. , Suyitno S. , Indraswari Kusumaningtyas I. K.

Archives of Foundry Engineering

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2021

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tom Vol. 21, iss. 4

87--92

EN

Casting is one method of making metal components that are widely used in industry and up to date. The sand casting method is used due to its simplicity, ease of operation, and low cost. In addition, the casting method can produce cast products in various sizes and is well-suited for mass production. However, the disadvantage of casting, especially gravity casting, is that it has poor physical and mechanical properties. Tin bronze Cu20%wt.Sn is melted in a furnace, then poured at a temperature of 1100°C into a sand mold. The cast product is a rod with 400 mm in length, 10 mm in thickness, and 10 mm in width. The heat treatment mechanism is carried out by reheating the cast specimen at a temperature of 650°C, holding it for 4 hours, and then rapid cooling. The specimens were observed microstructure, density, and mechanical properties include tensile strength and bending strength. The results showed that there was a phase change from α + δ to α + β phase, an increase in density as a result of a decrease in porosity and a coarse grain to a fine grain. In addition, the tensile strength and bending strength of the Cu20wt.%Sn alloy were increased and resulted in a more ductile alloy through post-cast heat treatment.