A hot top is a specialized riser lined with refractory or heat-generating materials to keep the feed metal molten as long as possible. It sits at the highest point of the mold to feed liquid metal downward, compensating for volumetric shrinkage as the main body solidifies. This prevents deep shrinkage cavities or piping inside the final piece.
Heard on the job
Make sure the hot top is fully ignited before you stop pouring, or we'll end up with a deep pipe in the ingot.
Insider tip
The metal left in the hot top is usually cropped off the ingot before rolling.
Also heard as
- feeder head