Characteristics of gray iron castings

Characteristics of gray iron castings

Gray iron castings boast high dimensional accuracy and require minimal machining allowances. Using ceramic precision casting technology, metal and gray iron castings are produced, with each part requiring only a tiny machining allowance. : Mold cavity surface 0.4mm; Mold Parting Surface 1.5 Millimeter ; Back and outer surface 3mm。

Gray iron castings maintain consistent performance in all directions, whereas steel, during forging or rolling, experiences deformation and elongation of non-metallic inclusions within its structure, resulting in varying mechanical properties across different directions—this phenomenon is known as “Anisotropy.” The properties of gray iron castings are consistent in all directions, giving them numerous advantages.

Gray iron castings exhibit superior high-temperature hardness compared to both structural steel and rolled steel—companies specializing in casting and forging. H-13 Tests conducted on mold steel showed that, at the same initial hardness and operating temperatures below 200 Below ℃, the hardness of cast steel is slightly lower than that of forged steel. 200 Above ℃, cast steel exhibits higher hardness than forged steel. Notably, as the temperature increases, this advantage in high-temperature hardness becomes increasingly pronounced, at 650 At ℃, the hardness value of cast steel is approximately higher than that of forged steel. 8HRC When gray cast iron castings are formed, the machining allowance on the cavity surface is minimal, allowing for the development of a fine-grained structure in the surface layer that resembles gemstones. As a result, gray cast iron castings exhibit excellent wear resistance.  

Good wear resistance and vibration damping properties. Since the graphite in cast iron promotes lubrication and oil retention, it exhibits excellent wear resistance. Similarly, gray cast iron outperforms steel in vibration damping thanks to the beneficial effects of its graphite content. It also boasts superior casting performance. With its high carbon content—close to the eutectic composition—the gray cast iron has a low melting point, excellent fluidity, and minimal shrinkage, making it ideal for producing complex-shaped or thin-walled castings. Moreover, because graphite easily forms chips during machining, gray cast iron offers better machinability compared to steel. The relationship between hardness and tensile strength : When O ≥ 196N/m When it comes to ㎡, HB = RH (Fe00 + 0.480 b) … (B1) b , when O ≥ 796 N/m At that time, HB = RH (44 + 0.7240b) ......(B2) In the formula, relative hardness (RH) Value is primarily determined by raw materials, melting processes, handling techniques, and the cooling rate of the castings. Advantages of using resin sand for casting machine tool components :(1) Resin sand offers excellent rigidity, while early casting sand provides high strength, creating ideal conditions for employing a graphitization-expansion process during the solidification of cast iron. This effectively eliminates defects such as shrinkage cavities and looseness, enabling low- or even no-runner casting of both gray and ductile iron. (2) Solid casting production employs polystyrene foam molding, utilizing furan resin for self-hardening. When molten metal is poured into the mold, the high temperature causes the foam pattern to rapidly vaporize and burn away, leaving behind a cavity that is precisely filled by the molten metal. As the metal cools and solidifies, it takes on the exact shape of the original foam mold, resulting in a solid casting with the same form and dimensions. In contrast, (3) For single-piece or small-batch production of automotive body panels, machine tool beds, and other components, the lost-foam process offers significant advantages over traditional sand casting. Not only does it eliminate the need for costly wooden patterns and provide convenient operation, but it also shortens the production cycle, boosting overall efficiency. Additionally, this method delivers high dimensional accuracy, minimal machining allowances, and superior surface quality.