Excerpt from the report by Ohio State Industrial, Welding and Systems Engineering professor R. Allen Miller.
2.1 Characterization of loads on die and machine
The die and the machine together function as a system. Analysis of both is important in understanding the distortions of the die. The die and the machine are subject to thermal and mechanical loads during the course of a casting cycle. These forces cause the die and machine behavior to change due to deflection and distortion of the components in their assembly. For studying the loads on the die casting die, the process has to be studied over an entire casting cycle. The forces can broadly be categorized as mechanical loads and thermal loads.
The different stages of a casting cycle are listed below:
1. The die locks up and a clamping force is applied.
2. Hot molten metal is injected at high temperature. The loads involved are due to momentum of incoming metal, heat released during the filling process, and the sudden pressure spike as the cavity becomes completely full.
3. The molten metal is held inside the die and an intensification pressure is applied during solidification.
4. The part is held in the die for a short time to remove additional heat.
5. The die is opened and the part ejected.
6. The die remains open for lubricant and cooling spray and the cycle repeats.