The use of Release Agents or Die Lubes are fundamental in high-pressure die casting processes. These lubricants are mainly made up of water-based chemicals (>99%), and a small amount of lubricating agents (<1%). Before the injection of molten metal, such as aluminum, die lubes are sprayed into the mold cavity to do the following:
1. Lower Die Temperature
Release agents help lower die temperature, operating at a high temperature due to heat transfer from the molten metal (600°C) to the die cavity. These prolong the economic life of the die.
Additionally, the 1% lubricating additives adhere to the cavity surface when die temperatures lower to 250°C. These additives form a protective film allowing release of the casting from the die cavity.
2. Release Casting from the Mold
The function of the lubricating agents in the die lube formulations is to create a thin film at the die cavity that separates the molten metal and the die. It prevents the casting from soldering or adhering, “releasing” a functional and useful casting free of deformation or defects.
However, this is difficult to attain because of multiple factors needed to consider in developing a “good uniform” barrier. It includes the variations of die surface temperatures (some areas are hotter than others), die lube chemistry, dilution ratios, spray volumes, spray timings, and mold designs.
3. Lubricate Die Components
Release Agents are essential to reduce friction on the moving parts (ex. ejector pins) to prevent premature wear of mechanical die components. This is achieved using mineral-based oil or synthetics in the die lube formulation.
