In impression-die forging, the workpiece acquires the shape of the die
cavities, while being forged between two shaped dies. During forging, some
of the material flows outward and forms a flash.
Close die forging is a special form of impression-die forging, flash
dose not form, and the workpiece completely fills the die cavities.
Processes
Reference 4
Step1. The hot material stock in block cavity.
Step2. Use machine to compress the die set and the material will change
shape.
Step3. Material flow fill the die cavity.
Step4. Final shape
Close die forging has two type of process.
Drop forging
Drop forging has several compression.The force come from the ram [hammer
free fall by gravity]. The ram lift by a single-acting steam (or air) cylinder.
Refence 1
Pressing forging
Use steady pressure instead of impacting pressure.
The energy is transmitted into the surface layers of the workpiece.
