The molten metal is cast in a rotating cylindrical mold.
From the start of the spinning process,
impurities migrate towards the center oh the ingot.
The solidification porcess is over :
all impurities have been segregated in the inner part of the cast tubular ingot.
Machining rids the cast tube of all conventional defects appearing in other types of castings, such as inclusions and porosities, making the final shape impurity free.
QA inspection and final control.