Drop forging is a metalworking process that shapes metal by repeatedly striking it with a heavy hammer while it is placed between shaped dies.
The drop forging process is a fundamental method in metal manufacturing used to create durable and strong components. It specifically uses a pair of impression dies and a heavy hammer to form and compress metal bars or billets into complex shapes.
Here's a breakdown of the key elements and process:
The Core Mechanism
At its heart, drop forging relies on brute force applied in a controlled manner. A piece of metal, often heated to a plastic state (though cold forging exists), is positioned on a lower die. An upper die attached to a heavy hammer is then brought down forcefully onto the metal. This repeated impact forces the metal to flow and fill the cavity between the two dies.
Key Components
- Impression Dies: These are crucial to the process. The dies contain an impression or die cavity, which is the desired shape of the final forging. The metal is pressed and hammered into these cavities.
- Heavy Hammer: This provides the impact force necessary to deform the metal.
- Metal Bar or Billet: The starting material, typically a cut length of metal, is placed between the dies.
- Equipment: The machinery used in this process is commonly known as a power or drop hammer.
The Process in Steps
- Heating: The metal billet or bar is often heated in a furnace to make it more malleable, reducing the force required for shaping.
- Placement: The heated metal is placed on the lower impression die.
- Hammering: The heavy hammer, with the upper die attached, is dropped or driven onto the metal. This is typically done in a series of blows.
- Forming & Compressing: Each blow compresses the metal and forces it to spread and fill the intricate die cavity. Multiple die cavities (e.g., for pre-shaping and finishing) may be used in sequence.
- Trimming: Excess metal that is squeezed out from between the dies during the process, known as flash, is later trimmed away.
- Finishing: The forged part may undergo further processes like heat treatment, cleaning, or machining.
By utilizing the powerful impact of a heavy hammer against shaped impression dies, drop forging efficiently forms metal bars or billets into complex and robust shapes, where the die cavity directly reflects the final desired component.
