3.4.2.3 Foundry Casting

Foundry casting processes include sand mold processes for essentially all alloys, evaporative pattern (lost foam) processes for iron and aluminum, and permanent mold processes for alloys with low melting temperatures such as aluminum and magnesium. The latter two alloy groups are also cast, in limited quantities, in plaster molds.

Forgings offers significant advantages over castings in applications where high reliability, high tensile strength or fatigue strength are required, frequently in combination with high ductility, impact toughness and fracture toughness. Forgings are free from porosity, which is difficult to eliminate in castings. This is particularly true in areas where geometric transitions occur, which are also areas of stress concentration.

The superior fracture toughness of forgings often must be considered when designing equivalent castings by applying a "casting factor" to account for casting process and product variations. This "casting factor" imposes a weight penalty that is often enough to make forgings the more economical choice, especially when weight is important.

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Foundry casting processes include sand mold processes for essentially all alloys, evaporative pattern (lost foam) processes for iron and aluminum, and permanent mold processes for alloys with low melting temperatures such as aluminum and magnesium. The latter two alloy groups are also cast, in limited quantities, in plaster molds.

Forgings offers significant advantages over castings in applications where high reliability, high tensile strength or fatigue strength are required, frequently in combination with high ductility, impact toughness and fracture toughness. Forgings are free from porosity, which is difficult to eliminate in castings. This is particularly true in areas where geometric transitions occur, which are also areas of stress concentration.

The superior fracture toughness of forgings often must be considered when designing equivalent castings by applying a "casting factor" to account for casting process and product variations. This "casting factor" imposes a weight penalty that is often enough to make forgings the more economical choice, especially when weight is important.

Return to Table of Contents

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Foundry casting processes include sand mold processes for essentially all alloys, evaporative pattern (lost foam) processes for iron and aluminum, and permanent mold processes for alloys with low melting temperatures such as aluminum and magnesium. The latter two alloy groups are also cast, in limited quantities, in plaster molds.

Forgings offers significant advantages over castings in applications where high reliability, high tensile strength or fatigue strength are required, frequently in combination with high ductility, impact toughness and fracture toughness. Forgings are free from porosity, which is difficult to eliminate in castings. This is particularly true in areas where geometric transitions occur, which are also areas of stress concentration.

The superior fracture toughness of forgings often must be considered when designing equivalent castings by applying a "casting factor" to account for casting process and product variations. This "casting factor" imposes a weight penalty that is often enough to make forgings the more economical choice, especially when weight is important.

Return to Table of Contents

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