Effects of Externally Solidified Product (ESP) on Wave Celerity and Quality of Die Cast Products

The cold chamber die casting process is the manufacturing method used to produce essentially all the die cast aluminum products and about 50% of the die cast magnesium products made today. Modeling of the cold chamber die casting process and metallographic observations of cold chamber die cast products indicate that typically 5 to 20 % of the shot weight is solidified in the shot sleeve before or during cavity filling. The portion of die casting which is solidified in the shot sleeve is referred to as externally solidified product, or "cold flakes". The externally solidified product significantly influences

1. the wave celerity and gas entrapment during the show shot stage of the process,

2. the fluidity of the alloy and its ability to completely fill the die cavity,

3. the microstructure of the resulting die casting, and

4. the mechanical properties of the resulting die casting.

This project is directed to extending the understanding of the effects of externally solidified product on the cold chamber die casting process and products to enable the production of defect-free diecastings and reduce the energy associated with these products. The projected energy savings from controlling the fraction of externally solidified product in die cast components is 0.04 quads (4*1013 BTU) through the year 2025.

The project involves three parallel activities:

1. Physical analog modeling with aqueous solutions under isothermal conditions with a second phase initially present on the shot sleeve wall, and a thermal conditions with solidification in transparent shot sleeves,

2. Computer modeling both the physical analog systems and aluminum die casting systems, and

3. Evaluating the quality of cold chamber die cast aluminum alloy components produced under controlled and monitored conditions with relatively small and large fractions of externally solidified products.