Q. What’s the most common quality concern you see in castings, and how do you address it?
A. One of the most common quality concerns we see in castings is slag and dross inclusions. These metallic oxides form when molten metal reacts with oxygen in the air. “Slag” typically refers to oxides from iron-based alloys, while “dross” refers to oxides from nonferrous alloys such as copper or bronze. When trapped inside a casting, both can cause machining issues or weaken the component.
Waukesha Foundry uses several preventative measures during melting, pouring, and mold design to reduce slag and dross inclusions:
- Using argon during melting – either bubbled from the bottom of the furnace or applied through a gas manifold.
- Regularly skimming slag or dross from the molten metal, since these oxides float and can be removed during melting.
- Incorporating filters in mold designs to capture slag and dross before they enter the mold cavity.
- Designing gating systems for smooth, efficient mold filling, minimizing oxide formation during pouring.
- Creating mold designs that allow inclusions to float up and out of the part.
- Flooding molds with argon before pouring to remove oxygen and prevent additional oxide formation.
These controls help ensure cleaner castings and more reliable components for our customers.