Die Casting

Soldering (sticking) is one of the most frustrating problems in die casting production—the casting becomes firmly "welded" to the mold surface, cannot be ejected, and production comes to a halt.

Why does soldering happen? High-temperature aluminum alloy undergoes a chemical reaction with the mold steel, forming intermetallic compounds that bond the two together. At the same time, the molten metal penetrates into micro-cracks on the mold surface, creating mechanical interlocks that make ejection even more difficult.

If soldering has already occurred (emergency response):

·Use a copper bar or oilstone to manually polish off the stuck metal, but be careful not to damage the mold surface.

·For complex molds, ultrasonic cleaning can be used—reducing cleaning time from 4 hours to just 45 minutes.

How to prevent it from the root:

·Lower the temperature: Reduce the alloy pouring temperature and mold temperature appropriately to minimize chemical reactions.

·Optimize design: Adjust gate position to avoid direct impingement of molten metal on cavity walls; enhance localized cooling, optionally using 3D-printed conformal cooling inserts for precise temperature control.

·Control material composition: For die-cast aluminum alloys, keep iron (Fe) content between 0.7% and 1.3%. Below 0.7% promotes soldering; above 1.3% degrades mechanical properties.

·Apply coatings: Use PVD or nitriding treatments to form a hard coating on the mold surface, isolating the molten metal from direct contact with the mold substrate.

Increase draft angle and reduce roughness: Increase the draft angle and polish the mold surface in the ejection direction to reduce ejection resistance.