Station 01 — Pouring
Riverbend Castings pours gray and ductile iron in Dubuque, Iowa. We make castings and we make the patterns that shape them. Everything we do happens on the way down.
The cooling curve — pouring, solidifying, machining
Station 02 — Molding & sand
Sand casting is the oldest trick in the trade and still the most flexible one. A pattern makes a cavity, the cavity holds the metal, and the metal takes the shape it is given. It is quiet, repeatable work — the part of the curve where the iron is still moving.
Sand is prepared and packed around the pattern until the mold is firm and the corners are true.
Cores sit inside the mold to hold the internal passages a casting needs and leave them hollow.
The mold is closed, weighted and made ready, and the sand waits for the iron to arrive.
Station 03 — Solidification
Both irons come out of the same furnace. What separates them happens in the seconds while the casting freezes, when the carbon inside either grows into flakes or rounds into nodules. That single difference sets the whole character of the part.
Carbon freezes as flakes that thread through the metal. Those flakes make gray iron a natural damper — it swallows vibration and machines freely — which is why it suits bases, housings and anything that has to sit still and hold its shape.
Damping · Machinability · Thermal stability
A treatment in the ladle turns the graphite into nodules instead of flakes. Rounded graphite does not cut the metal the way a flake does, so ductile iron takes more load and actually stretches before it fails — the difference between a part that cracks and a part that yields.
Strength · Ductility · Impact resistance
Station 04 — Pattern & machining
Every casting is a copy of a pattern. We build them here, so the accuracy a part needs is settled before the first pour — and the first pour is not a guess.
Casting gives the rough shape; machining makes it accurate. Once the iron is cool and settled, we take the surfaces a drawing calls out down to size, with the crisp edges the cold end of the curve is named for.
Station 05 — Room temperature
This is the end of the curve, and the point of the whole page. Here is what we do, and here is how to ask us for it.
Flake graphite iron for parts that need to hold their shape, damp vibration and machine cleanly.
Nodular graphite iron where the part has to carry load, take a knock and yield rather than crack.
Molds packed, closed and poured on site — the core of everything that leaves the floor.
Cast surfaces taken to size after the iron has cooled and finished moving.
The tooling the whole casting is a copy of, built in-house.
Send the drawing or describe the part. Tell us which iron you have in mind, or tell us what the part has to do and we will talk it through.
Riverbend Castings
Dubuque, Iowa
Gray & ductile iron