In die casting process selection, a hot-chamber (gooseneck) die casting machine is typically used for casting which category of alloys based on melting temperature and reactivity with the machine’s immersed components?

Introduction / Context:

Die casting employs either hot-chamber or cold-chamber machines. The choice depends primarily on the alloy’s melting temperature and its chemical attack on the machine hardware. Understanding this selection is fundamental in manufacturing process planning for components like housings, gears, and covers.

Given Data / Assumptions:

• Hot-chamber machines immerse the injection mechanism (gooseneck) in the molten metal bath.
• Concerns include corrosion/erosion of immersed parts and thermal limits.
• Common die-cast alloys include Zn, Mg, Al, Cu-based systems (with variations).

Concept / Approach:

Hot-chamber die casting is ideally suited to low-melting, non-ferrous alloys that do not excessively attack the immersed gooseneck components—classically zinc and some magnesium alloys. Alloys like aluminum and brass/bronze (higher melting and more reactive) are typically cast in cold-chamber machines to avoid hardware degradation and to handle higher temperatures.

Step-by-Step Solution:

Verification / Alternative check:

Process charts in manufacturing texts show Zn die castings predominantly using hot-chamber machines; Al die castings generally use cold-chamber machines.

Why Other Options Are Wrong:

• Ferrous alloys: die casting is not used for ferrous alloys at typical machine limits.
• Non-ferrous high-melting: favors cold-chamber due to temperature and reactivity.
• Superalloys: unsuitable for standard die casting hardware and temperatures.

Common Pitfalls:

• Assuming aluminum is always hot-chamber; it is predominantly cold-chamber.

Final Answer:

non-ferrous alloys with low melting temperature