In centrifugal casting method, core is used.

Explanation:

Core: 

• Cores are used to get the internal cavity in the castings.
• Cores are placed into the mould after the removal of the casting. These are made up of sand are used in permanent moulds also.
• The cores are surrounded by molten metal and therefore subjected to severe thermal and mechanical conditions.
• Core sand should be of higher strength than the moulding sand.

Centrifugal casting:

• In centrifugal casting, molten metal is poured into the revolving metallic mould.
• The molten metal falling into the centre of the mould at the axis of its rotation is whirled out by the power of centrifugal force towards the periphery and the impurities being lighter in weight, are left behind at the centre.
• Due to the application of centrifugal force, the casting is completely free from any porosity defect, denseness and strength are high and these castings have been proved as strong as forgings.
• Metal is filled due to centrifugal action hence hollow parts is produced without using core in this method.
• No gating element is used process used to produce hollow cylindrical objects (symmetrical) in mass production without using core.

Application:

• Hollow cylindrical pipes.
• Gun barrels.
• Large size bushes.
• Propeller shafts.