Centrifugal casting is a metal casting process used at Goodrich Gasket Pvt. Ltd. to form cylindrical parts using centrifugal force rather than gravity or pressure to fill the mould. In centrifugal casting, a permanent mould made from steel, cast iron, or graphite is typically used. However, the use of expendable sand moulds or refractory moulds is also possible.
The casting process at Goodrich Gasket Pvt Ltd is usually performed on a horizontal centrifugal casting machine(vertical machines are also available) and includes the following steps:
- Mould preparation- Walls of a cylindrical mould are first coated with a refractory ceramic coating in a steps (application, rotation, drying, and baking). Once prepared and secured, the mould is rotated about its axis at high speeds (300-3000 RPM), typically around 1000 RPM.
- Pouring - Molten metal is poured directly into the rotating mould, without the use of runners or a gating system. The centrifugal force drives the material towards the mould walls as the mould fills.
- Cooling -With all of the molten metal in the mould, the mould remains spinning as the metal cools. Cooling begins quickly at the mould walls and proceeds inwards.
- Casting removal - After the casting has cooled and solidified the rotation is stopped and the casting is removed.
- Finishing -Finishing - While the centrifugal force drives the dense metal to the mould walls, any less dense impurities or bubbles flow to the inner surface of the casting. As a result, secondary processes such as machining, grinding, or sand-blasting, are carried out by Goodrich Gasket to clean and smoothen the inner diameter of the part.
Centrifugal casting is used to produce axis-symmetric parts, such as cylinders or disks, which are typically hollow at Goodrich Gasket Pvt. Ltd. Due to the high centrifugal forces; these parts have very fine grain structures on the outer surface. These parts may be cast from ferrous metals such as low alloy steel, stainless steel, and iron, or from non-ferrous alloys such as aluminum, bronze, copper, magnesium, and nickel.
Centrifugal casting done at Goodrich Gasket offers typical products including tube plates, flanges etc for boilers; bearings, bushes, thrust washers, gear blanks, seals, pressure vessel, flanges, casting rings for engineering industry; bearings, cushion and conveyor rollers for mining; pump cylinders, pipes / tubes for oil rigs; reformer furnace tubes for petrochemical; bearings and drive hubs for marine etc.
True Centrifugal casting:-
The true centrifugal method of casting produces hollow castings with a round hole which is produced by the centrifugal force alone and no cores. A speed that creates a centrifugal force of 60G – 75G on horizontal moulds and 100G for vertical moulds are provided at Goodrich Gasket to hold the metal on to the mould wall.
Semi – Centrifugal Casting:-
In semi-centrifugal casting process no attempt is made to produce a hole without a core. The centrifugal force resulting from rotation of the mould is used to properly feed the casting to produce a close grained clean casting . At Goodrich Gasket this process is applied for large axis-symmetrical castings like gear blanks of special requirements for our customers.
Centrifuging or centrifuge casting is employed by Goodrich Gasket to force a metal under pressure into moulds of small castings or castings not symmetrical about any axis of rotation. The moulds are made around a central axis of rotation, to balance each other. Centrifuging helps in proper feeding of castings resulting in clean, close grained castings.