Sheet Metal Stamping & Blanking Die Vector DXF Preparation Guide: Clearances, Tonnage & Nesting
An essential engineering guide for die makers, metal fabricators, and stamping engineers converting 2D part drawings into high-speed progressive die tooling geometry.
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1. The Foundation: Piercing vs Blanking Clearance Allocation
In sheet metal stamping, the clearance between punch and die determines whether sheared part edges exhibit clean burnish bands with minimal burrs or suffer heavy rollover and tearing. However, beginners often make the catastrophic mistake of applying clearance to the wrong tool component.
- Hole Piercing: The Punch determines hole dimension. Make the punch equal to nominal hole size; make the die opening larger by $2c$.
- Part Blanking: The Die Matrix determines outside blank dimension. Make the die opening equal to nominal blank size; make the punch smaller by $2c$.
Use our free Metal Stamping & Blanking Die Clearance Calculator to compute exact tool diameters, cutting forces, and press tonnages.
2. Edge Cross-Section: Rollover, Burnish, Fracture & Burr
When the punch contacts the sheet metal strip, the shear progression creates four distinct vertical zones:
- Rollover (5-10% t): Initial plastic deformation rounding the top edge.
- Cut / Burnish Band (30-40% t): The smooth, shiny vertical surface created by the sharp punch edge.
- Fracture Zone (50-65% t): The micro-rough matte slope where the opposing crack fronts meet.
- Burr (≤ 5% t): The minute lip formed as the fracture tears out of the die matrix.
Too tight clearance causes secondary shearing (double burnish band) and doubles tool wear. Too loose clearance causes extreme rollover and giant, hazardous burrs.
3. Strip Layout, Web Width & Carrier Bridges in Progressive Dies
In high-speed progressive dies running at 100 to 1,200 strokes per minute, parts remain connected to the coil strip via carrier tabs until the final cutoff station. Vector prepress requires strict geometric constraints:
If the web strip between parts is too narrow, the carrier will bow upwards during high-speed feeder indexing, causing die jam-ups and sensor trips.
4. Punch Fillets and Corner Stress Concentration
Sharp 90° inside corners on punch tool steel (D2, A2, DC53, Vanadis 4 Extra) act as severe stress risers during cyclic impact. During heat treatment (58-62 HRC) and press operation, sharp inside corners develop microscopic fatigue cracks that propagate until the punch tip chips.
- Inside Radii Rule: Always specify a minimum fillet radius $R \ge 0.5 \times t$ (or at least 0.5 mm) at every internal intersection.
- G02/G03 Arc Fitting: In DXF prepress, ensure that all corners are modeled as true mathematical arcs rather than micro-segmented polylines.
Converting Part Blueprints into Clean Stamping Die DXF Vectors?
SpotItLive Vector Studio converts raster scans, PDF spec sheets, and hand sketches into clean, closed-loop 2D DXF and SVG geometry with tangent arc smoothing, ready for Wire EDM, CNC milling, and CNC turret punching CAM systems.
Vectorize Stamping Geometry →5. Stamping Tooling Material & Heat Treatment Matrix
| Tool Steel Grade | Hardness (HRC) | Wear Resistance | Toughness / Chipping Resistance | Primary Die Application |
|---|---|---|---|---|
| AISI D2 / 1.2379 | 58 - 62 HRC | High (12% Cr) | Moderate | General blanking & piercing dies (< 2mm steel) |
| AISI A2 / 1.2363 | 57 - 60 HRC | Moderate | Good (Air Hardening) | Intricate punch shapes, tight tolerances |
| DC53 (Modified D2) | 60 - 62 HRC | Very High | 2x Tougher than D2 | Heavy gauge punching, stainless steel stamping |
| Powder Metal (CPM-1V / Vanadis 4) | 60 - 64 HRC | Extreme | Superior Chipping Resistance | High-strength automotive steel (DP800 / Boron) |
| Tungsten Carbide (10-15% Co) | 88 - 91 HRA | Maximum | Brittle (requires rigid sub-plates) | Lamination stamping, million-stroke runs |