Category: Casting & Forming Reading time: 7 min Meta description: Metal stamping design rules — progressive dies, material selection, minimum features, tolerances, and cost factors. Design stampable parts that save tooling cost. URL: /blog/metal-stamping-design/ Tags: stamping, metal-stamping, progressive-die, die-design, forming
Metal stamping is the go-to process for high-volume metal parts. At tens of thousands of parts per year, it's often the only process that makes economic sense.
But stamping has strict design rules. A part designed for laser cutting and bending may be impossible or uneconomical to stamp. Understanding these rules early in the design phase saves significant tooling cost.
The most common high-volume process. A strip of metal feeds through a multi-station die. Each station performs a different operation — pierce, notch, form, draw, trim, cut-off.
Speed: 200-1,000+ strokes per minute Tooling cost: $5,000-30,000 Part range: Small to medium, 100-500mm
Best for: High volume (50,000+ parts/year), small to medium parts that fit on a progressive strip.
Individual blanks are transferred between separate dies by mechanical fingers. Used for larger parts that don't fit in a progressive strip.
Speed: 15-30 strokes per minute Tooling cost: $15,000-80,000 Part range: Medium to large, up to 2,000mm
Best for: Large parts, deep-drawn parts, moderate volume.
A single die performs one operation per stroke. Used for low-volume parts, large parts, or parts with unusual shapes that can't be progressed.
Speed: 30-60 strokes per minute Tooling cost: $1,000-8,000 Part range: All sizes
Best for: Low volume (1,000-10,000/year), large parts, prototypes.
Not all materials stamp equally. The key property is elongation — how much the material can stretch before cracking.
| Material | Elongation (%) | Formability | Cost | Applications |
|---|---|---|---|---|
| Mild steel (SPCC, DC01) | 30-45% | Excellent | Low | Brackets, enclosures, panels |
| Galvanized (SGCC, DX51D) | 25-35% | Good | Low-Med | Outdoor, electrical |
| Stainless 304 | 40-60% | Good | Medium | Kitchen, medical |
| Stainless 430 | 20-30% | Fair | Medium | Decorative, appliance |
| 5052 Aluminum | 20-30% | Good | Medium | Marine, electronics |
| 6061 Aluminum | 15-25% | Fair | Medium | Structural (limited draw) |
| Copper (C110) | 30-45% | Excellent | High | Electrical contacts |
| Spring steel (65Mn, SK5) | 5-10% | Poor | Medium | Springs, clips, washers |
| Brass (C2680) | 35-50% | Excellent | High | Decorative, connectors |
| Feature | Formula | Example (1.5mm steel) |
|---|---|---|
| Hole diameter | ≥ 1.0 × material thickness | 1.5mm minimum |
| Slot width | ≥ 1.5 × t | 2.25mm |
| Hole-to-edge distance | ≥ 1.5 × t | 2.25mm |
| Hole-to-hole spacing | ≥ 2.0 × t | 3.0mm |
| Minimum tab width | ≥ 2.0 × t | 3.0mm |
| Minimum bend length | ≥ 4.0 × t + bend radius | 7.5mm (with R1.5) |
| Corner notches | ≥ 3.0 × t | 4.5mm |
Minimum bend radius:
| Material | Perpendicular to grain | Parallel to grain |
|---|---|---|
| Mild steel | 0.4-0.6t | 0.8-1.0t |
| Stainless steel | 0.5-0.8t | 1.0-1.5t |
| Aluminum | 0.3-0.5t | 0.6-1.0t |
| Spring steel | 1.0-2.0t | 1.5-3.0t |
Bend relief notches: Always add a small notch (2-3t wide, 1-2t deep) at the intersection of a bend line and a cut edge. Without this, the material will tear during bending.
| Feature | Standard | Precision |
|---|---|---|
| Hole position (pitch) | ±0.1mm | ±0.05mm |
| Hole diameter | ±0.05mm | ±0.025mm |
| Formed dimensions (bend-to-hole) | ±0.2mm | ±0.1mm |
| Flatness (per 100mm) | ±0.3mm | ±0.1mm |
| Burr height | <10% of t | <5% of t |
The strip layout is the most important and expensive part of progressive die design. Key parameters:
Carrier types: | Carrier | Application | |---|---| | Center carrier | Small parts, symmetrical | | Edge carrier | Most common, simple | | Dual carrier | Large parts, unstable parts | | Tab carrier | When full edge needed |
| Part Complexity | Stations Required |
|---|---|
| Simple blanking (no forming) | 4-6 stations |
| Moderate (some bends) | 8-12 stations |
| Complex (multiple bends + form) | 12-20+ stations |
| Deep draw | 15-25+ stations |
Each station adds $500-2,000 to die cost.
Many stamped parts need secondary operations that add cost:
| Operation | Cost Added | Notes |
|---|---|---|
| Thread tapping | $0.02-0.10/hole | Needs post-stamping operation |
| Welding | $0.10-1.00/weld | Spot or projection welding |
| Heat treat | $0.05-0.50/part | For spring steel |
| Plating/painting | $0.10-2.00/part | Batch process |
| Assembly | $0.05-0.50/part | Hardware insertion |
| Factor | Cost Impact |
|---|---|
| Die complexity (# stations) | High — each station adds cost |
| Number of bends | Moderate — each bend adds a station |
| Tight tolerances | Moderate — more maintenance, higher scrap |
| Material thickness | High — thicker = stronger press required |
| Quantity | High — run time vs die amortization |
| Material choice | Moderate — stainless costs 2-3x mild steel |
| Process | Best Quantity | Tolerance | Tooling Cost | Per-Part Cost |
|---|---|---|---|---|
| Laser cutting + bending | 1-1,000 | ±0.2mm | $0 | $5-50 |
| Turret punching | 100-10,000 | ±0.1mm | $0-500 | $1-20 |
| Progressive stamping | 10,000+ | ±0.05mm | $5,000-30,000 | $0.05-0.50 |
| Transfer die | 5,000+ | ±0.1mm | $15,000-80,000 | $0.50-3.00 |
| Fine blanking | 10,000+ | ±0.02mm | $15,000-50,000 | $0.15-2.00 |
Submit your stamped part design to app.moldkey.com/quote for tooling cost estimates and per-part pricing from experienced stamping suppliers.