Centrifugal casting or rotocasting is a casting technique that is typically used to cast thin-walled cylinders. It is chiefly used to manufacture rotationally symmetric stock materials in standard sizes for further machining, rather than shaped parts tailored to a particular end-use.

Advantages
By casting and sintering high quality alloy powder on barrel inside surface with thickness1.5-2.0mm, screws can get higher performance in both wearing & corrosion resistant performance.