China Deep Drawn Stamping Products & Exporter

Deep drawn metal stamping represents one of the most sophisticated plastic deformation processes in modern industrial manufacturing. Unlike conventional sheet metal bending or flat blanking, deep drawing transforms flat sheet metal blanks into seamless, three-dimensional axisymmetric or box-shaped hollow vessels—such as cylindrical cans, rectangular enclosures, parabolic reflectors, and complex stepped shells. This transformation occurs under severe radial tensile stress and tangential compressive stress, requiring meticulous control over material anisotropy, blank holding pressures, tooling clearances, and inter-stage annealing schedules.

Deformation Zones in Deep Draw Kinematics

During the punch stroke, the metallic blank is subjected to five distinct strain environments simultaneously. Understanding these localized deformation physics allows Sunmy Hardware's die design engineers to eliminate flange wrinkling, sidewall earing, and bottom fracturing:

• 1. The Flange Zone: Experience high radial tension combined with intense circumferential compression. Without calibrated Blank Holder Force (BHF), tangential compressive stress causes severe flange wrinkling (buckling instability).
• 2. The Die Radius Zone: The sheet metal bends over the die edge while sliding under high friction. This zone experiences combined bending stress, unbending strain, and axial tension.
• 3. The Sidewall Zone: Pure tension stretches the metal formed from the flange. The material undergoes strain hardening (work hardening), which increases sidewall tensile strength while reducing ductility.
• 4. The Punch Radius Zone: The area of maximum stress concentration. The punch nose presses into the metal, creating a high localized strain zone where wall thinning is most pronounced.
• 5. The Punch Bottom Zone: Unstretched or minimally deformed material that retains its original blank thickness, serving as the mechanical base of the vessel.

DFM Rules for Engineering Teams

When drafting CAD designs for custom deep drawn products, adhering to standard Design For Manufacturability (DFM) guidelines drastically lowers tooling tooling costs and accelerates production ramp-up:

1. Punch Nose Radius ($R_p$): Specify a punch radius between 4x and 8x blank thickness. Radius values smaller than $4t$ create sharp stress concentrations leading to bottom punch-through.
2. Die Edge Radius ($R_d$): Maintain die radii between 6x and 10x sheet thickness. Too small a die radius restricts material flow, causing sidewall necking; too large a radius induces unchecked flange wrinkling.
3. Corner Radii on Rectangular Boxes: Corner draw radii ($R_c$) should be as large as possible. Deep drawn rectangular cans require progressive corner pre-forms to balance corner compression against straight wall tension.
4. Wall Taper and Draft Angles: While deep drawing yields parallel vertical walls, incorporating a slight $0.5^\circ$ to $1.0^\circ$ draft angle facilitates rapid mechanical ejection and extends die lifespan.