When people think about centrifugal casting they usually think about horizontal or vertical casting, not both. A common question we are asked at tradeshows, via e-mail and through our website, www.centrifugalcastingmachineco.com is why choose horizontal over vertical centrifugal casting and vice versa and how do you know which type is best for your parts?
Commonly, a foundry man might think that the centrifugal casting process is only used for cylindrical shaped parts, such as rolls, pipe, sleeves, tubes or liners. This isn’t true. However, the previously mentioned shapes are commonly cast via the horizontal centrifugal casting process. Back in the 1940s when Centrifugal Casting Machine Company (CCMCO) was founded in Tulsa, Oklahoma, a lot of work was being done in the development of casting non-cylindrical shaped parts such as valves, sheaves, gear blanks and sprockets that could be cast using the vertical centrifugal casting method.
So, why would one choose to use horizontal centrifugal casting over vertical centrifugal casting? Generally, horizontal centrifugal casting is best applied to castings of greater length than the diameter and which have a cylindrical bore. This is why you will commonly find tube shapes of between 12” (305 mm) up to 20’ (6000 mm) long cast horizontally. Vertical centrifugal casting, on the other hand, is commonly used for cylindrical shapes where the diameter exceeds the length (or height) of the casting, like rings or bearings. As mentioned above, non-cylindrical shaped parts such as valves, propellers, etc. are also cast using vertical centrifugal casting. Additionally, other specialty castings, like conical shaped castings and ball valve balls, are cast using the vertical centrifugal casting process.
Both horizontal and vertical centrifugal casting processes can be used with ferrous and non-ferrous materials. The machines themselves are not aware of the material being spun. It is through the application of different process techniques, like duration of water cooling and rates of pouring and spinning that different materials, such as copper and cast iron, can successfully be poured into the same type of equipment and quality castings can be achieved.
Vertical and horizontal castings not only differ by the casting shapes that can be cast, but also by how the molten material acts in the machine. “Although both vertical and horizontal methods employ centrifugal force, there are some differences in how the force is applied with respect to the axis of the mold rotation and the speed for molten metal relative to the rotating mold. For example, with a vertical mold axis, the resultant force on the liquid is constant. This is not the case in a horizontal mold. The other difference between horizontal and vertical mold orientation is the speed obtained by the molten metal as it spins around the mold. When metal is poured into the horizontally rotating mold, considerable slip occurs between the metal and the mold such that the metal does not move as fast as the rotating mold. To overcome this inertia, the metal must be accelerated to reach the mold rotation speed. This is not a problem in the vertical centrifugal process, where the molten metal reaches the speed of the mold soon after pouring. However, with a vertical mold axis, there is a tendency for the molten metal to form a parabolic shape due to the competing gravitational and centrifugal forces.” (Dr. Sufei Wei, ASM Handbook, Volume 15, Pg. 667)
Both machines can offer a fairly manual set up where cycle times are largely determined by operator speed up to 100% automated equipment, where one operator operates one or more machines in a high production setting. CCMCO supplies a full line of both types of machinery and can help you determine which type is best suited for your needs.