Heavy Casting

Introduction: Heavy casting products are used for large and heavy applications which can way be as heavy as as 8,000lbs. Heavy casting is used to cast products for different types of heavy end application in the fields of agriculture, aircrafts, automobile industry. Large castings are produced using different types of casting materials like carbon steel, low to medium alloy steel, Ni-Hard & gray & ductile iron.

»  Process and Materials: In heavy casting sand and alumina mixture is used to make mold. In some cases moldings are also made with metallic boxes. In a small casting sand of fine grain in needed containing a lot of alumina than the coarser grained sand need for heavy casting. And since the heat required in more, the sand required is more. And silica required is more than alumina as there is need for venting. Alumina and Magnesia are important factors for molding sand, since sand gets dried on heating. The same grade of sand cannot be used for heavy and small work. For heavy molding 88% sand, 6% Alumina and 46 degree of fineness is required. Molds for heavy castings also require venting across the sides.

Pattern shop & pattern making companies use various materials to make patterns for heavy casting, such as seasoned teak wood, aluminum, epoxy resin, cast iron and expandable polysterene. Automatic roll over machine removes the pattern and leaves the mold for further further processing. Melting can be done in the induction furnace. The casting process can be open hearth, besemers process, etc.

Molten metals that are used for heavy casting include aluminum, nickel, copper, stainless steel, bronze, Monel, chrome copper, copper silver, zirconium copper, aluminum bronze, manganese bronze & tin bronze, spinodal bronze alloys, chrome zirconium copper alloys, etc. These metals can be casted in a using different casting depending upon the the design of the products, the alloys used and the availability of the finance.

»  Cleaning: Heavy castings are cleaned either by pickling or by sand blast. In pickling the casting are placed on a platform the bottom of which slope from each side to the center. Sulphuric acid mixed with water with water is thrown on the casting and kept for 12 hours. They are then washed in hot water. The water should be so hot that the water shoud dry and not rust. The action of the acid is to eat the layer of iron oxide which forms on the outside of the casting. When this is done, clean iron is left exposed. In the sand blast process, sand is blown against the cast with great force. This is a very effective way of cleaning.

»  Application: Valve components, piping system components, mineral & gas exposed components, steam turbine parts, crusher equipment parts, mining equipment parts, food processing equipment & power generation components, driving boxes and cross heads for locomotives, heavy or large machined castings made from ferrous materials. Agricultural casting, aircraft components, etc.