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.

scholarly journals Influence of Pattern Coating Thickness on Porosity and Mechanical Properties of Lost Foam Casting of Al-Si (LM6) Alloy

2013 ◽  
Vol 300-301 ◽  
pp. 1281-1284
Author(s):  
Shamsuddin Sulaiman ◽  
M.K.A.M. Ariffin ◽  
S.H. Tang ◽  
A. Saleh
Keyword(s):  
Mechanical Properties ◽  
Molten Metal ◽  
Coating Thickness ◽  
Air Entrainment ◽  
Expanded Polystyrene ◽  
Lost Foam Casting ◽  
Polystyrene Foam ◽  
Porosity Distribution ◽  
Foam Pattern ◽  
Lost Foam

The combination of Aluminum alloy with lost foam casting (LFC) process is best applied in automotive industry to replace steel components in order to achieve light weight components for reducing fuel consumption and to protect the environment. The LFC process involves process parameters such as the degree of vacuum, foam degradation, expanded polystyrene (EPS) foam density, permeability of foam pattern coatings, pouring temperature, filling velocity, cooling rate, and pressure. The effect of polystyrene foam pattern coating thickness on the porosity and mechanical properties of Aluminum Al-Si LM6 alloy were evaluated experimentally. The coating thickness was controlled by slurry viscosity at range between 18sec to 20sec using Zahn viscosity cup No.5 and the foam pattern was coated up to fifth layer. Aluminum Al-Si (LM6) molten metal was poured into expandable mould and castings were examined to determine porosity distribution, mechanical properties and microscopic observation. Results from X-ray testing reveal the porosity distribution on Aluminum Al-Si LM6 castings is greater at thicker foam pattern coating sample. Meanwhile, the tensile strength of casting decreases when foam pattern coating thickness increases. Microscope observation portray the present of porosity on the casting which shows more gas defects present at thicker foam pattern coating sample. The source of porosity in LFC process is due to air entrainment or the entraining gases from polystyrene foam decomposition during pouring of molten metal. As a conclusion, mechanical strength has inverse relationship with porosity.

scholarly journals PRODUCTION OF ROTARY ENGINES’ PARTS FROM ALUMINUM ALLOYS USING LOST FOAM CASTING PROCESS

2018 ◽  
pp. 16-21
Author(s):  
E. I. Marukovich ◽  
A. M. Branovitskiy ◽  
A. A. Kruglov ◽  
V. A. Dement’ev ◽  
N. P. Sadovskiy
Keyword(s):  
Aluminum Alloy ◽  
Aluminum Alloys ◽  
Production Technology ◽  
Casting Process ◽  
Expanded Polystyrene ◽  
Lost Foam Casting ◽  
Rotary Engine ◽  
Rotary Engines ◽  
Lost Foam

The production technology of casting details for rotary engine from the aluminum alloy АК12М2 is developed. The bulk density of expanded polystyrene to ensure the best quality of the surface of castings has been experimentally established. The lost foam casting shop was organized in the experimental department of the Institute.

Numerical Modeling of EPS Foam Decomposition in the Lost Foam Casting Process

2005 ◽  
Author(s):  
X. J. Liu ◽  
S. H. Bhavnani ◽  
R. A. Overfelt
Keyword(s):  
Heat Transfer ◽  
Process Parameters ◽  
Experimental Studies ◽  
Casting Process ◽  
Mold Filling ◽  
Lost Foam Casting ◽  
Interfacial Heat Transfer Coefficient ◽  
Filling Process ◽  
Foam Pattern ◽  
Lost Foam

The importance of smooth mold filling in the lost foam casting process has been recognized for a long time. The more uniform the filling process, the better the quality of the casting products that are produced. Successful computer simulations can help reduce the number of trials and cut down the lead time in the design of new casting products by better understanding the complex mechanisms and interplay of different process parameters in the mold filling process. In this study, a computational fluid dynamics (CFD) model has been developed to simulate the fluid flow of molten aluminum and the heat transfer involved at the interfacial gap between the metal and the expanded polystyrene (EPS) foam pattern. The commercial code FLOW-3D was used because it can track the front of the molten metal by a Volume of Fluid (VOF) method and allow complicated parts to be modeled by the Fractional Area/Volume Ratios (FAVOR) method. The code was modified to include the effects of varying interfacial heat transfer coefficient based on gaseous gap pressure which is related to foam degradation and coating permeability. The modification was validated against experimental studies and the comparison showed better agreement than the basic model. Process parameters such as initial metal temperature, foam pattern property, and gating system were investigated. The defect prediction model was also used to study the dependence of defect formation on the process variables.

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.

Experimental Study of EPS Decomposition in Lost Foam Casting Process

2001 ◽  
Author(s):  
Ying Liu ◽  
Sayavur I. Bakhtiyarov ◽  
Ruel A. Overfelt
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heat Source ◽  
Casting Process ◽  
Expanded Polystyrene ◽  
Chamber Pressure ◽  
Neutral Atmosphere ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Close Proximity ◽  
Foam Pattern

Abstract The thermal degradation of bulk and miniature samples of expanded polystyrene (EPS) has been investigated in a neutral atmosphere at 800°C and by differential scanning calorimetry over a range of temperatures. The differential scanning calorimetry experiments showed that the foam volatilization temperature is significantly affected by heating rate and varies from 380°C to 470°C at heating rates from 10–60°C/min. Bulk degradation due to the 800°C heat source appeared to occur instantly as the foam pattern approached the close proximity of the heat source. The chamber pressure increased and the heat source temperature dropped during degradation. The gas yield at 800°C was determined to be about 610 cm3 (STP)/g of EPS.

Sign in / Sign up

Export Citation Format

Share Document