scholarly journals Gas Pressure Effect on Sand Collapse in Kinetic Zone of Lost-Foam Casting

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Joo Mae Jeon ◽  
Soo Jo Lee ◽  
Kyeong Hwan Choe ◽  
Jeung-Soo Huh
Keyword(s):  
Lead Time ◽  
Void Ratio ◽  
Casting Process ◽  
Nodular Cast Iron ◽  
Gas Pressure ◽  
Lost Foam Casting ◽  
Essential Factor ◽  
Metal Tip ◽  
Casting Experiment ◽  
Lost Foam

Pressure of the kinetic zone is an essential factor for making defect-free castings in lost-foam casting process. The extremely high pressure causes many problems, such as reducing the melt velocity and inclusion of residual decomposition of the pattern in the castings, and very low pressure causes sand collapse. Therefore, the minimum gas pressure for preventing sand collapse is required. When the minimum gas pressure can be predicted, computer simulation becomes possible. Successful computer simulations can help reduce the number of trials and the lead time while designing new casting products. A preliminary sand experiment was conducted to predict the gas pressure and reduce the number of actual casting experiments. In this preliminary sand experiment, compressed air was used instead of gas in the kinetic zone. A new mathematical equation was proposed from the results of the preliminary sand experiment. The void ratio of the sand effect on the minimum gas pressure was included in the equation. An actual casting experiment was conducted by melting nodular cast iron to verify this equation. In the actual casting experiment, pressure of the kinetic zone in front of the metal tip was directly measured. The results obtained from the preliminary sand experiment and the actual casting experiment validated the equation.

Synthesis and Characterization of New Refractory Coatings Based on Talc, Cordierite, Zircon and Mullite Fillers for Lost Foam Casting Process

2014 ◽  
Vol 59 (1) ◽  
pp. 89-95 ◽  
Author(s):  
A. Prstić ◽  
Z. Aćimović-Pavlović ◽  
A. Terzić ◽  
L. Pavlović
Keyword(s):  
Microstructural Analysis ◽  
Casting Process ◽  
Lost Foam Casting ◽  
X Ray Diffraction ◽  
X Ray ◽  
Software Application ◽  
Design And Optimization ◽  
Refractory Coatings ◽  
Particle Size And Shape ◽  
Lost Foam

Abstract Refractory coatings based on different refractory fillers (talc, cordierite, zircon and mullite) for application in Lost Foam casting process were investigated. Design and optimization of the coatings composition with controlled, rheological properties included, and consequently synthesis were achieved by application of different coating components, namely different suspension agents and fillers and by alteration of the coating production procedure. Morphologic and microstructural analysis of fillers was carried out by means of scanning electronic microscope. X-ray diffraction analysis by means of X-ray diffractometer was applied in determination and monitoring the phase composition changes of the refractory fillers. An analysis of the particle size and shape was carried out by means of the PC software application package OZARIA 2.5. To assess the effects of application of individual refractory coatings, a detailed investigation of structural and mechanical properties of the moldings obtained was performed. Highlight was placed on revealing and analyzing surface and volume defects present on moldings. Radiographic molding tests were carried out by means of the X-ray device SAIFORT type-S200. Attained results are essential for the synthesis of refractory coatings based on high-temperature fillers and their applications in Lost Foam casting process for manufacturing of moldings with in-advance-set properties.

Numerical Simulation of Molten Metal-Polymeric Foam Interface Velocity During Lost Foam Casting

2001 ◽  
Author(s):  
Sayavur I. Bakhtiyarov ◽  
Ruel A. Overfelt
Keyword(s):  
Molten Metal ◽  
Flow Model ◽  
Interface Velocity ◽  
Casting Process ◽  
Lost Foam Casting ◽  
Foam Material ◽  
Polymeric Foam ◽  
Gaseous Products ◽  
3D Software ◽  
Lost Foam

Abstract A novel multiphase flow model is presented for describing the pyrolisis of polymeric foam material in a lost foam casting process. FLOW-3D software (Flow Science, Inc.) has been used to simulate liquid metal filling dynamics and the molten metal-polymeric foam interface velocity in foam patterns of rectangular shape. The effect of the degradation gaseous products on the molten metal-polymeric foam interface velocity was taken into consideration through specially written sub-routing program. The results of the simulations are compared with the previously obtained experimental data for the lost foam iron casting.

Numerical simulation of heat transfer and fluid flow of molten metal in MMA–St copolymer lost foam casting process

2010 ◽  
Vol 210 (14) ◽  
pp. 2071-2080 ◽  
Author(s):  
Ali Charchi ◽  
Mostafa Rezaei ◽  
Siyamak Hossainpour ◽  
Jamal Shayegh ◽  
Sohrab Falak
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Fluid Flow ◽  
Molten Metal ◽  
Casting Process ◽  
Lost Foam Casting ◽  
Lost Foam

Thermal Analysis during Solidification of Mg-4%.wtAl Alloy during Lost Foam Casting Process

2011 ◽  
Vol 686 ◽  
pp. 371-377 ◽  
Author(s):  
D.H. Hou ◽  
S.M. Liang ◽  
Rong Shi Chen ◽  
En Hou Han ◽  
C. Dong
Keyword(s):  
Thermal Analysis ◽  
Grain Size ◽  
Casting Process ◽  
Expanded Polystyrene ◽  
Solidification Structure ◽  
Lost Foam Casting ◽  
Dendrite Morphology ◽  
Dendrite Coherency ◽  
Foam Pattern ◽  
Lost Foam

The lost foam casting (LFC) process utilizes the expanded polystyrene (EPS) foam pattern for the production of metallic components. The thermal degradation of the foam pattern has a significant effect on microstructure of the component. Dendrite coherency is important for the determination of the formation of the solidification structure and cast ability of alloys. The effects of the dendrite coherency on grain size in Mg-4Al alloy have been studied using the two-thermocouple thermal analysis technique in the solidified sample. The results also indicate that the grain size increases with the temperature interval between liquids (TN) and dendrite coherency point (TDCP), The solid fraction at DCP (fsDCP) expressed in percent strongly dependents on the dendrite morphology during solidification.

Measurement of Kinetic Zone Temperature and Heat Transfer Coefficient in the Lost Foam Casting Process

2004 ◽  
Author(s):  
X. J. Liu ◽  
S. H. Bhavnani ◽  
R. A. Overfelt
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Casting Process ◽  
Lost Foam Casting ◽  
Foam Pattern ◽  
Lost Foam ◽  
The Heat Transfer Coefficient ◽  
Zone Temperature

A thermometric technique has been developed to study the thermal characteristics of the foam-metal interaction in the lost foam casting process. A cylindrical foam pattern and heated steel block have been used to estimate the endothermic losses associated with the thermal degradation of the expanded polystyrene at the metal front. Thermocouple readings have been analyzed to determine the temperature of the kinetic zone between the advancing metal front and the receding foam pattern. The heat transfer coefficient between the metal front and the foam pattern has been calculated from the thermal data at the simulated metal front. The results confirmed that the endothermic degradation of the polystyrene pattern at the metal front introduced a steep thermal gradient in the metal and a consistently increasing heat flux. It is found that the heat transfer coefficient, initially 150 W/m2·K increases to 220 ~ 300 W/m2·K during the process. Foam density has marginal effect on the heat flux and heat transfer coefficient, whereas the increase of simulated metal front velocity enhances the heat transfer at the metal front. The kinetic zone temperature is measured to be in the range of 150 to 290°C with an average of 200°C and a gaseous gap size of 1 to 4 cm.

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