Cast iron manifold is also called as exhaust manifold or inlet manifold, normally produced by gray iron ASTM A48 CL 30, 35, DIN GG20, GG25, or known as grey iron class 200 and 250.
Dandong Foundry in China produced manifold castings for our client overseas by shell molding process. We used hot resin sand molds to make the shell and core of the castings. This casting process could meet the requirements to the surface quality, casting defects, and thin wall thickness.
The clean inside tubes and less casting defects are the key points of the quality, which is impossible to meet by the traditional green sand casting processes. The following photo is showing these resin sand shell and cores.
Gray cast iron GG20, or class 200 is the most suitable casting material for the manifold. It is mainly because gray iron has cheaper production costs, good cast properties, good resistance to deformation and heating. Some clients may choose GG25, e.g. class 250 grades because of higher tensile strength, however, manifolds normally have very thin wall thickness such as 5 to 6mm, which will cause the hardness of the castings higher, which will cause difficulty for drilling. Moreover, higher grade will cause the casting bodies more crispy.
The prices of manifold castings are not low because its difficulty to production, and high prices of yellow phenolic resin sand. Normally, one set of manifolds needs several sets of metal patterns, and their sand molds need assembly, which will cause much more production process and time. There are not many iron foundries in China who could produce the manifolds very well.
This article is from our Dandong Foundry's Cast Iron Manifold.
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