Hole diameter in metal stamping: what is the rule?

At least 1× the material thickness (about 1.2× for stainless or hard materials). Punches break on small holes.

Hole to edge in metal stamping: what is the rule?

At least about 1.5× the material thickness. Material between hole and edge distorts or tears.

Bend radius in metal stamping: what is the rule?

At least about 1× the material thickness. Tighter bends crack.

Grain direction in metal stamping: what is the rule?

Bend across the rolling grain where strength matters. Bending along the grain cracks more easily.

Tooling and volume in metal stamping: what is the rule?

Dies cost thousands to tens of thousands; use laser cutting and a press brake until volumes justify a die. The die pays off only at volume.

Metal stamping: design rules

Pressing sheet metal into shape with dies; very cheap per part at volume, expensive to tool.

Typical tolerance

Typical: about ±0.05–0.1 mm in progressive dies.

Files to send

STEP and a drawing with tolerances, burr direction and material grain direction.

Common materials

Steel, stainless, aluminium, brass, copper.

The rules, with reasons

Hole diameter. At least 1× the material thickness (about 1.2× for stainless or hard materials). Why: Punches break on small holes.
Hole to edge. At least about 1.5× the material thickness. Why: Material between hole and edge distorts or tears.
Bend radius. At least about 1× the material thickness. Why: Tighter bends crack.
Grain direction. Bend across the rolling grain where strength matters. Why: Bending along the grain cracks more easily.
Tooling and volume. Dies cost thousands to tens of thousands; use laser cutting and a press brake until volumes justify a die. Why: The die pays off only at volume.

Before you ask for a quote

Material, grade and thickness
Annual and first-order quantity
STEP and drawing
Burr direction and grain direction
Finish and packaging

Common mistakes

Ordering a die too early
Holes smaller than the thickness
No burr or grain direction on the drawing

Agents and scripts can check a design automatically with the check_design MCP tool or POST /api/design-rules. How to connect.

Request a quote Find manufacturers

Typical rules of thumb, not a guarantee. The manufacturer's own design guidelines override them: ask for them and check your design against both before ordering.