Why Does a Newly Cast Aluminum Launder Need to Be Baked in an Oven?

thoroughly drying and preheating the refractory lining. If molten aluminum is poured directly into the channel without prior baking, it may cause cracking, aluminum seepage, aluminum adhesion, blistering, material loss, and even safety incidents involving aluminum leaks.

1. Remove Moisture — The Most Important Reason

Refractory castables are normally mixed with water during installation. After casting, the material may contain:

• Free water
• Pore water
• Chemically bound water

If a wet launder is suddenly exposed to molten aluminum at around 700°C, the water can rapidly turn into steam.

This can cause:

Cracking → Spalling → Refractory Failure → Molten Aluminum Splashing

In severe cases, it can create a significant safety hazard.

2. Allow Moisture to Escape Gradually

The outside surface of a thick launder may become dry while moisture remains trapped inside.

A controlled oven allows the launder to be heated gradually:

Low temperature → Medium temperature → High temperature

with appropriate holding times at each stage.

This allows moisture to migrate from the inside to the outside and escape safely.

3. Improve Refractory Stability

Proper baking helps stabilize the refractory lining and prepares it to withstand:

• High temperature
• Thermal shock
• Molten aluminum flow
• Repeated heating and cooling cycles

This reduces the risk of cracking, spalling, and premature failure during the first use.

4. Reduce Heat Loss During Operation

A cold launder absorbs a large amount of heat from the molten aluminum.

This can result in:

Lower aluminum temperature → Reduced flowability → Aluminum buildup → Possible blockage

Newly cast launder
↓
Curing
↓
Controlled oven baking
↓
Remove internal moisture
↓
Stabilize the refractory material
↓
Preheat before operation
↓
Introduce molten aluminum

The Key Point

The main purpose of oven baking is not simply to make the launder hot. It is to safely and thoroughly remove moisture from the refractory castable and stabilize the refractory structure before the launder comes into contact with molten aluminum.