Introdution

Forging is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer (often a power hammer) or a die.

Classification by Temperature

Forging is often classified according to the temperature at which it is performed:

• Cold Forging: A type of cold working.

• Warm Forging: Performed at intermediate temperatures.

• Hot Forging: A type of hot working; the metal is heated, usually in a forge.

Scope and Application

Forged parts can range in weight from less than a kilogram to hundreds of metric tons. While traditionally used for kitchenware, hardware, and hand tools, since the Industrial Revolution, forged parts have become essential in mechanisms and machines where components require high strength. These forgings usually require further processing, such as machining, to achieve a finished part. Today, forging remains a major worldwide industry.

Advantages

1. Structural Integrity & Strength

Forging can produce a piece that is stronger than an equivalent cast or machined part.

• Internal Grain Deformation: As the metal is shaped, its internal grain deforms to follow the general shape of the part.

• Continuous Grain Flow: The grain is continuous throughout the part, giving rise to improved strength characteristics.

2. Total Cost of Ownership (TCO)

Forgings can target a lower total cost compared to casting or fabrication. When evaluating a product’s lifecycle, the long-term benefits of forgings often outweigh short-term savings by reducing:

• Procurement lead times

• Rework and scrap

• Downtime and quality issues

3. Material Considerations

• Iron and Steel: Almost always hot forged to prevent work hardening, which would increase the difficulty of secondary machining operations.

• Hardening Methods: While work hardening is sometimes desirable, methods like heat treating are generally more economical and controllable.

• Specialty Alloys: Alloys amenable to precipitation hardening, such as most aluminium alloys and titanium, can be hot forged followed by specific hardening processes.