Effect of Process Parameters on the Solidification Time of Al-7%Si Alloy Castings Produced by VAEPC Process

Abstract

Casting is a manufacturing route that is of fundamental importance in the processing of metals because of its ability to produce complex shapes cheaply. A recent development, the Evaporative Pattern Casting (EPC) process, holds the promise of revolutionizing the manufacture of castings, making the process even more economically attractive. One serious limitation of this process is blow holes in the castings. The blow holes and/or gas porosity in EPC castings is because of the non-escape of the gas produced as a result of burning of polystyrene pattern in the sand mold. The hybrid-casting process is developed to improve the quality of castings. The developed hybrid-casting process has been termed as Vacuum-Assisted Evaporative Pattern Casting (VAEPC) process. This aricle investigates the effect of process parameters like degree of vacuum, pouring temperature, grain fineness number, amplitude of vibration, and time of vibration on the solidification time of Al-7%Si alloy castings. In order to evaluate the effect of selected process parameters, the Response Surface Methodology (RSM) is used to formulate a mathematical model that correlates the independent process parameters with the desired solidification time. The central composite rotatable design has been used to conduct the experiments. The analysis of results indicates that the solidification time decreases with increase in the degree of vacuum, amplitude of vibration, and time of vibration. However, solidification time increases with increase in pouring temperature and grain fineness number.

Keywords:

• Al-7%Si alloy
• Amplitude of vibration
• Castings
• Central composite rotatable design
• Coating metarial
• Degree of vacuum
• Grain fineness number
• Ishikawa cause effect diagram
• Polystyrene pattern
• Pouring temperature
• Pouring time
• Response Surface Methodology (RSM)
• Solidification time
• Time of vibration
• Vacuum-assisted evaporative pattern casting process

ACKNOWLEDGMENT

The authors acknowledge the Department of Science and Technology, India for funding the above work.

Notes

∗Half replications.

Std. dev 0.049 R-squared 0.9226

Mean 7.53 Adj R-squared 0.8737

C.V. 0.66 Pred R-squared 0.7555

PRESS 0.15 Adeq precision 19.533

Significant at 95% confidence level, #The model is hierarchical.