Which type of die casting utilizes gas rings to keep the molten metal heated?

The correct choice refers to pressure die casting, which is a process that utilizes a high-pressure mechanism to inject molten metal into a mold. In this method, gas rings may be employed to maintain the temperature of the molten metal as it is injected into the die, ensuring that it flows smoothly and fills the cavity completely before solidifying.

This method is particularly advantageous in producing complex shapes with fine details and allows for faster production rates compared to other casting techniques. The maintenance of molten metal temperatures is crucial in pressure die casting as it minimizes the risk of defects such as porosity or poor surface finish, which can arise from premature cooling of the metal during the injection process.

In contrast, gravity die casting relies solely on the force of gravity to fill the mold, and does not utilize gas rings for temperature maintenance. Hot chamber casting involves a different process where the metal is kept molten within a chamber, suitable for specific alloys, but it does not utilize gas rings either. Sand casting, while versatile and widely used, primarily relies on gravity and does not incorporate any gas ring mechanisms.