For centuries, casting has played a vital role in manufacturing. The casting of metals remains important today. It facilitates the production of numerous industrial parts.
During the metals casting process, a manufacturer uses heat and one (or more) molds to change the shape of a solid metal permanently. Liquid metal will cool into a shape determined by the mold, for instance.
The Centrifugal Casting Process
Centrifugal casting (or “rotocasting”) constitutes a highly specialized form of casting. Invented by Alfred Krupp, this process permits the mass production of cylindrical parts and metal rings and discs through the use of spinning molds. Fabricators rely upon centrifugal forces to disperse molten metal evenly through the mold. This results in the generation of finely grained, densely compacted metal workpieces.
Initially, a manufacturer prepares a centrifugal mold by applying one or more coatings to the surface and heating the mold to a desired temperature. After the mold begins spinning at a selected rotational rate, the manufacturer places a runner into position and begins the filling process.
Centrifugal forces help spread the molten material evenly. The metal cools as the mold continues to spin. Manufacturers may choose to maintain a constant high temperature for a specified period of time through the selective use of coolants. After the molten metal solidifies and cools, the manufacturer pulls the workpiece from the mold, e.g. with the assistance of a pipe puller. Today many high volume production environments completely automate the centrifugal casting process.
Types of Centrifugal Casting
Metal parts manufacturers rely upon a variety of different types of centrifugal casting processes:
True Centrifugal Casting
True centrifugal casting does not require the use of an interior mold core. The spinning of the symmetrical mold around its central axis causes the metal to disperse through the mold and create a cylindrical casting with a hollowed rounded interior.
Under carefully controlled conditions, this form of casting utilizes molten metal efficiently.
Manufacturers produce a variety of metal parts utilizing true centrifugal casting, including engine cylinders, ring pistons, and pipes.
Semi Centrifugal Casting
During semi centrifugal casting, the addition of a central core to the mold determines the shape of the interior hole in the casting. The production process still relies upon rotating molds to obtain finely grained castings.
This process allows modifications of the shape of the hollowed interior of a cast ring or cylinder.
Some products manufactured using semi centrifugal casting include track wheels, railroad car wheels and fly wheels.
Centrifuge casting involves spinning several small molds around a central axis, much as test tubes rotate positioned within a centrifuge. The individual molds grouped in this manner may include asymmetrical molds. Typically, molten metal enters the mold via a central sprue and disperses through the interior along a network of precut channels.
This process generates several small parts with compact, fine grains.
Manufacturers often utilize centrifuge casting to help form gears and other disc-shaped metal components.
Materials And Applications
Centrifugal casting permits the high volume production of parts suitable for machining. It allows manufacturers to create cylindrical and disc or ring-shaped work pieces conveniently and cost-effectively:
In this century, industrial part manufacturers employ centrifugal casting as a process for creating components from a variety of metals and metal alloys. Some popular raw materials for this type of casting include iron, stainless steel, steel, aluminum, copper, and nickel.
Facilities may invest significant sums in the creation of the permanent molds used during centrifugal casting. Since manufacturing with this process involves both high temperatures and the need to rotate molds at controlled rates of speed, plants may incur comparatively higher energy production costs than with some other casting processes. Centrifugal casting lends itself to automation, so despite the initial investment it frequently offers a very efficient manufacturing process, especially for firms engaging in high volume production runs.
Numerous applications exist for centrifugal casting. Originally developed to permit the fabrication of stronger, more uniform train wheels, today this process contributes to the production of a variety of other industrial metal parts, as well.
For example, manufacturers can utilize this process to create metal pipes and tubes in a variety of dimensions without having to weld seams. Additionally, centrifugal casting will produce metal rings and discs, as well as very thin-walled cylindrical components. It can assist companies in producing pipes and tubes with internal, firmly bonded cladding. Other common applications include the production of coils, bushings, bearings, pulley components and wheels.
Centrifugal Casting Advantages
Centrifugal casting offers a variety of benefits. First, since these cast parts solidify with more finely compacted metal grains than the castings produced by other manufacturing processes, they tend to provide stronger, more corrosion-resistant workpieces for machining and finishing purposes. Manufacturers may discover the use of this process to form castings helps reduce the rejection rate during finishing, for instance.
Second, the process of centrifugal casting works well in conjunction with automation. Since every element of this casting process benefits from careful control (including the preparation of the molten metal, the quantities of raw materials used, the speed of pouring, the rotational speed of the mold, the temperature of the mold during rotation and the length of time the mold spins), automating this process helps to generate more uniform castings.
Third, centrifugal casting proves versatile. It produces symmetrical castings of virtually any diameter and length. These items display excellent mechanical properties.