Closed die forging is a process that achieves plastic forming of metal using a closed die cavity.
Its core features include:
No flash or minimal clearance: The die has no flash grooves, and the clearance between the male and female dies is parallel to the direction of die movement and remains constant, preventing the formation of lateral flash.
Precision forming: It can produce high-precision forgings, with high material utilization and improved product reliability.
Applications: Widely used in the manufacture of complex structural parts such as deep-sea pressure-resistant and corrosion-resistant valve bodies, aerospace landing gear, nuclear power pipe fittings, and new energy vehicle components.
Necessary conditions for normal operation include:
Precise control of billet volume;
Rational die structure design;
Sufficient tonnage equipment;
Good lubrication and precise guide systems.
What is the process flow for closed die forging? The closed-die forging process can be divided into the following key steps, combining common technical points for different application scenarios (such as aluminum alloy wheels and universal joint forks):
1. Blanket Preparation
Blanking: The blank volume is calculated based on the forging weight. The closed-die blanking coefficient is typically 1.05-1.1 (for example, the weight of an aluminum alloy wheel blank is calculated to be 17.86 kg).
Heating: Induction heating or low-oxidation heating is used, with strict temperature control (e.g., 1200 ± 30°C).
2. Die Design and Preheating
Die Structure: A split die or closed cavity design is used, requiring precise positioning (e.g., controlling flash on the die parting surface in universal joint forging).
Preheating: The die should be preheated to above 200°C and lubricated with aqueous graphite to reduce friction.
3. Die Forging
Deformation Stage:
Open Upsetting Stage: The metal freely fills the die cavity. Split-flow extrusion stage (e.g., universal joint forks): The metal flows laterally and then bends downward to fill the fork-shaped cavity.
Upsetting/extrusion final forging: This is performed on a screw press or hydraulic press (e.g., a 1600t press for final forging of aluminum alloy wheels).
4. Subsequent Processing
Flash Removal: A small-gap trimming die is used to remove longitudinal flash formed on the parting surface.
Heat Treatment: Aluminum alloy wheels, for example, require solution aging treatment (6082T6 material).
Finishing: Precision areas such as ball tracks and spline holes are CNC machined after a 0.3-0.4mm allowance.
Key Process Control Points
Blank Positioning: Eccentricity can lead to uneven metal flow or longitudinal flash.
Energy Control: Closed-die forging has 30%-50% lower deformation forces than open-die forging, but precise forging termination timing is required.
Material Utilization: This can reach 85%-95%, significantly higher than traditional forging. This process is suitable for axisymmetric or short-axis rotational parts (such as gears, bearing rings, and aircraft blisks).
The above is an introduction to closed-die forging. Generally, reliable forging companies will provide detailed information on the process features when you submit your request, so you can understand the manufacturing costs for your product. Of course, if you require large quantities of forged parts, you can partner with Mulan Metal. With 12 years of experience in metal forging production and processing, Mulan Metal specializes in custom forgings for various flanges, shafts, gears, and swing arms. We have completed commissioned production of various custom forgings in over 30 countries and have received widespread recognition. We look forward to your consultation and cooperation.
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