Nodular Cast Iron Product by Casting and Machining

China OEM customized nodular iron castings products by sand mold casting process and CNC machining. 

Ductile cast iron, which is represent a group of cast iron, also called nodular iron, spheroidal graphite cast iron or SG iron. Nodular cast iron obtains nodular graphite through spheroidization and inoculation treatment, which effectively improves the mechanical properties of the cast iron, especially the plasticity and toughness, so as to obtain higher strength than carbon steel.

Ductile iron is not a single material but is part of a group of materials which can be produced to have a wide range of properties through control of the microstructure. The common defining characteristic of this group of materials is the shape of the graphite. In ductile irons, the graphite is in the form of nodules rather than flakes as it is in grey iron. The sharp shape of the flakes of graphite create stress concentration points within the metal matrix and the rounded shape of the nodules less so, thus inhibiting the creation of cracks and providing the enhanced ductility that gives the alloy its name.

Nodular cast iron has rapidly developed into a cast iron material second only to gray cast iron and widely used. The so-called "substituting iron for steel" mainly refers to ductile iron. Ductile iron is often used to produce parts for crankshafts and camshafts for automobiles, tractors, and internal combustion engines, as well as medium-pressure valves for general machinery.

In the design stage of ductile iron casting products, a special project team should be set up to conduct "Design Failure Mode and Effects Analysis" (DFMEA). The project team generally consists of product designers, casting process designers, and environmental protection professionals. The main content of the DFMEA analysis should include whether the requirements of the casting quality for the part structure, the casting process for the casting structure, and the casting process for environmental protection requirements are all met.

Performance Characteristics of Ductile Iron Castings:
• Fluidity and line shrinkage of ductile iron are very close to those of gray cast iron
• The tendency of volume shrinkage and internal stress formation is greater than that of gray cast iron, which is prone to shrinkage and cracks
• The strength, plasticity, and elastic modulus of ductile iron are larger than those of gray cast iron, with good abrasion resistance
• Shock absorption is worse than gray cast iron

Structural Characteristics of Ductile Iron Castings:
• Generally designed to be uniform wall thickness, and try thick section should be avoid if possible
• For certain thick and large section castings, hollow structure or structure with reinforced ribs should be adopted

Advantages of Sand Casting Process:
• Low Cost due to its cheap and recyclable mold materials and simple production equipment.
• Wide range of unit weight from 0.10 kg to 500 kgs or even bigger.
• Various Structure from simple type to complex type.
• Suitable for production requirements of various quantity.