27 December 2016

Difference between forging and casting

What is casting?

Casting is a process in which metal is heated until the molten stage and poured or forced this metal into a mould or cavity such that the metal solidifies and takes the shape of the mould. 

    Types of casting are gravity casting (including sand casting and die casting) and pressure casting (including low-pressure casting and high-pressure casting).

    What is forging?

    Forging is a process of reforming a metal shape by applying pressure with or without heat. 

    Types of forging are impression die forging, cold forging, open die forging and seamless rolled ring forging. 

    Now, let us have a deep insight into the comparison between them and check it out the difference between them too. 

    Difference : 

    • In casting metal is heated until it converts into a molten stage wherein forging metal is heated below re-crystallization temperature. 
    • A product produced by the casting process has low fatigue strength and by forging process has high fatigue strength. 
    • Imperfection or defects does not improve in casting and defects are refined in the forging process.
    • The casting process is less reliable or has low strength while forging process is highly reliable.
    • Casting is costly sometimes and has a high lead time where forging has low lead time and cheap as compared to casting.
    • The product produced by the casting process has low tensile strength while forging product has high tensile strength.
    • Casting process required a secondary finishing operation while forging process not required. 
    • The product produced by the casting process has high compressive strength as compare to forging. 
    • The casting process involves pouring of molten metal into a mould for cooling while in forging can be done to cold, warm and hot metal depending on the requirement of the final product.
    • The product produced by casting has a low tensile strength than the forging. 
    • Forging is costly sometimes and has high lead time whereas forging has low lead time and cheap. 
    • Casting process response to heat treatment requires close control due to the probability of alloy segregation while in forging a response to heat treatment is better.