Metal stamping is a manufacturing process where flat metal sheets are formed into desired shapes using stamping dies and presses. It is categorized into two main types:
Cold Stamping — Performed at room temperature, suitable for steel sheets, aluminum sheets. Most common method (85%+ of production volume).
Hot Stamping (Hot Forming) — Sheet heated to 900°C+ then stamped and simultaneously quenched in the die. Used for high-strength steel (1,500 MPa+ tensile) — mainly automotive structural parts.
Separation Operations:
• Blanking — Cutting the outline of a part from sheet
• Punching — Creating holes or cutouts
• Trimming — Removing excess material
• Notching — Cutting notches from edges
Forming Operations:
• Bending — Angled and U/V-shape bends
• Deep Drawing — Forming cups, housings, and deep shapes
• Flanging — Creating flanges along edges
• Embossing — Raised or recessed patterns
Mechanical Presses — Crank type (high speed), eccentric type, knuckle-joint type. Speed: 30-800 SPM (strokes per minute).
Hydraulic Presses — Single action (most common), double action (deep drawing), triple action. Speed: 5-30 SPM.
Servo Presses — Programmable motion profile, energy efficient. Speed: 10-80 SPM.
Typical press capacity in Chinese factories: 25-2000 tons. Most automotive suppliers have 400-2500 ton presses.
Single-Station Die — One operation per stroke. Simple, low cost.
Progressive Die (Progressive Tooling) — Multiple stations in sequence, strip fed through. High efficiency for high-volume parts.
Compound Die — Multiple operations (blank + form) at one station.
Transfer Die — Part transferred between stations. Suitable for complex parts.
Die materials: Cr12MoV, SKD11, DC53 (cold work steel) / H13, 3Cr2W8V (hot work steel)
Key quality metrics for stamped parts:
1. Dimensional accuracy: Typical tolerance IT10-IT14
2. Burr height: ≤5% of sheet thickness (controlled by die clearance)
3. Springback: Compensation by over-bending (typically 2-5 degrees)
4. Surface defects: No scratches, dents, or marks
5. Cracking: No cracks in drawn areas
Chinese stamping factories typically measure using CMM (coordinate measuring machine), profile projector, and go/no-go gauges.
China is the world's largest metal stamping market. Major clusters:
Yangtze River Delta: Shanghai, Suzhou, Kunshan — Automotive stamping hub
Pearl River Delta: Guangzhou, Dongguan, Shenzhen — Consumer electronics, appliances
Central China: Wuhan, Hefei — Automotive OEM supply
Chengdu-Chongqing: Automotive + home appliances
Tooling lead time: 25-45 days. Production sample turnaround: 7-14 days after tool approval.