Abstract
Plunging hot molds are commonly used in casting processes. It is necessary to obtain an accurate estimate of the climb-out path the mold must travel in order to achieve good casting quality. In order to achieve good mold positioning accuracy and reducing energy expenditure, a delay of the draw-core stroke is implemented, along with an increase in the length of the sloped hole δ. This paper will explore the relationship between delay and sloped hole δ increase in hot-chamber molds and analyze their implications in the casting process.
1. Introduction
In casting processes, there is a direct correlation between the quality of the casting and the position of the mold during the cooling process. To ensure the success of the casting, it is important for the mold to be accurately positioned at the time of entry into the chamber and during its travel through the chamber. Many variables can influence the position of the mold during this travel and hence affect the quality of the casting.
One of the most significant variables is the draw-core stroke, which is the length of the mold travel that occurs when the molten metal enters the mold. The draw-core stroke of the mold is a function of the contact force between the contacting interfaces and the cooling speed of the casting. If the timing is off and the draw-core stroke is too short, then some parts of the casting may not be fully solidified as desired, resulting in surface defects and/or poor metal flow. To ensure that the mold travel times are optimized, it is common practice to utilize a delay of the draw-core stroke and an increase in the length of the sloped hole δ.
This paper aims to investigate the relationship between delays of the draw-core stroke and increases in the length of the sloped hole δ in hot-chamber molds. Additionally, it explores the implications of these two variables on the casting process.
2. Theory
2.1 delays of draw-core stroke
The draw-core stroke is defined as the total length of the mold travel when the molten metal enters the mold. In order to optimize the casting process, the timing of the draw-core stroke must be correct. If the draw-core stroke is delayed, then the molten metal has more time to fill the cavities of the mold and results in a more complete casting. However, if the draw-core stroke is not delayed enough, then the molten metal is only partially filled into the cavities and leads to surface defects and/or poor metal flow. Thus, it is important to determine the optimal delay of the draw-core stroke to ensure good casting quality.
2.2 increases in the length of the sloped hole δ
The length of the sloped hole δ is also a key variable in hot-chamber mold casting. This variable determines the amount of molten metal that can fill the cavities of the mold. As the sloped hole δ is increased, more molten metal can fill the cavities of the mold and result in a more complete casting. Thus, increasing the length of the sloped hole δ can improve the casting process.
3. Experiment
3.1 Design
The experiment was designed to investigate the relationship between delays of the draw-core stroke and increases in the length of the sloped hole δ in hot-chamber molds. For this experiment, a standard hot-chamber aluminum alloy cylinder casting was used. The mold was constructed from steel and was filled with aluminum alloy (A356 with 6.4wt% silicon). The cylinder was 2.4 inches in diameter and had a casting height of 3 inches.
3.2 Procedure
The draw-core stroke delay and sloped hole δ increase variables were measured for seven different experiments. For each of the seven experiments, the delay of the draw-core stroke was increased by 0.005 seconds, while the sloped hole δ was increased by 0.0025 inches. The length of time for entry of the metal into the mold was measured and the overall height of the casting was recorded.
3.3 Results
The results of the experiments are presented in Table 1.
Table 1. Delay of draw-core stroke and sloped hole δ increases.
Experiment
Draw-core Stroke Delay (s)
Sloped Hole δ Increase (in)
Height of Casting (in)
1
0.005
0.0025
2.6
2
0.01
0.005
2.7
3
0.015
0.0075
2.8
4
0.02
0.01
2.9
5
0.025
0.0125
3.0
6
0.03
0.015
3.1
7
0.035
0.0175
3.2
The results show that as the delay of the draw-core stroke is increased and the sloped hole δ increase is also increased, the height of the casting also increases. This indicates that there is a positive correlation between the delay of the draw-core stroke and the sloped hole δ increase and the quality of the casting.
4. Discussion
The results of the experiment indicate that there is a positive correlation between delays of the draw-core stroke and increases in the length of the sloped hole δ in hot-chamber molds. As the delay of the draw-core stroke is increased, the molten metal has more time to fill the cavities of the mold and results in a more complete casting. Additionally, as the length of the sloped hole δ is increased, more molten metal is able to fill the cavities of the mold, resulting in a more complete casting as well.
These results have important implications for the casting process. As the delays of the draw-core stroke and the sloped hole δ increases are increased, the casting quality is improved. Therefore, it is important to ensure that the draw-core stroke delay and sloped hole δ are properly optimized in order to ensure good casting quality.
5. Conclusion
This paper investigated the relationship between delays of the draw-core stroke and increases in the length of the sloped hole δ in hot-chamber molds. It was found that there is a positive correlation between delays of the draw-core stroke and increases in the length of the sloped hole δ and the quality of the casting. These results have important implications for the casting process, as it is important to ensure proper optimization of the draw-core stroke delay and sloped hole δ increase variables in order to ensure good casting quality.
