Blechstanzen: Prozess, Toleranzen & Design Guide

Kernaussagen

• Stanzen is the fastest way to produce flat and formed Blech parts at scale — cycle times as low as 1 second per part with progressive dies, making it the go-to process for brackets, clips, shields, and enclosures above 5,000 units.
• Prozess choice depends on part geometry and volume — blanking and piercing for flat parts, Biegen for simple forms, progressive die for complex multi-feature parts, deep drawing for hollow shells.
• Standard Stanzen Toleranzen are ±0.13 mm (0.005″) for hole diameters, ±0.25 mm (0.010″) for edge-to-hole positions — tighter than laser-cut-only parts because the die controls dimensions repeatably.
• Die cost dominates at low volume — a simple single-stage die costs $800–$3,000; a progressive die with 8–12 stations runs $8,000–$25,000. Below 1,000 units, Laserschneiden + CNC Biegen is usually cheaper.
• Burr direction is a critical DFM detail — stamped edges always have a burr on one side. Specify burr direction on the drawing to avoid assembly interference.
• Material choice affects both tool life and part cost — mild steel (SPCC) is the most stampable; stainless and high-strength steels accelerate die wear and need more frequent tool maintenance.

Was ist Blechstanzen?

Blech Stanzen is a cold-forming process that uses a punch and die set in a mechanical or hydraulic press to cut, bend, or draw flat Blech into finished parts. Unlike CNC-Bearbeitung which removes material, or Laserschneiden which only cuts profiles, Stanzen simultaneously cuts and forms — producing complete parts with holes, bends, tabs, and embossed features in a single press stroke or a sequence of progressive stations.

The process is ideal for parts that are flat or shallow-formed, produced in quantities above 1,000–5,000 units, and require consistent dimensions across a long Produktion run. Common stamped parts include mounting brackets, electrical contacts, spring clips, EMI shields, automotive body panels, and appliance housings.

In the world of custom Blechfertigung, Stanzen fills the gap between low-volume laser-cut prototyping and high-volume dedicated Produktion. A fabricator with in-house Stanzen capability can offer you both prototype flexibility and Produktion economics without switching Zulieferers mid-project.

Vier Hauptarten des Blechstanzens

Am besten geeignet für: Blanking when you need flat parts with precise hole patterns. Progressive die when part count exceeds 10,000 and the part has 3+ features. Deep drawing when you need hollow cylindrical or box-shaped parts.
Avoid when: Progressive die below 5,000 units — die amortization per part makes unit cost higher than laser + bend. Deep drawing for materials with low elongation (some Aluminiumlegierungs crack at draw ratios above 1.8).

Stanztoleranzen: Was realistisch erwartet werden kann

Toleranzen in Stanzen are driven by the die, not the operator — which means they are inherently more repeatable than manually positioned Laserschneiden or press brake Biegen. However, they vary significantly by feature type:

When your part has features that must locate relative to each other within a tight tolerance, specify GD&T datum references on the drawing rather than linear ± dimensions. This tells the die designer which features to use as the primary locating surfaces and which Toleranzen can stack.

Am besten geeignet für: Using standard Toleranzen for all non-critical features — tighter Toleranzen increase die cost by 20–40%. Reserve precision Toleranzen for hole patterns that locate mating components, connector cutouts, and press-fit features.
Avoid when: Specifying ±0.05 mm on overall length of a 300 mm part — thermal expansion alone can shift dimensions by 0.03 mm per 10°C temperature change.

Materialauswahl für Stanzteile

Am besten geeignet für: SPCC steel for 90% of general Stanzen work — it is the most forgiving, least expensive, and longest tool-life material. 5052 aluminum when weight matters. Spring steel only when the part must function as a spring.
Avoid when: Specifying 316 stainless for a simple indoor bracket — the material premium and accelerated die wear add cost with no functional benefit over 304.

DFM-Regeln für Stanzteile

Good Stanzen DFM reduces die cost, extends tool life, and improves part consistency. These six rules apply to nearly every stamped part:

1. Hole diameter must be at least 1× Materialstärke. Punching a hole smaller than the Materialstärke causes punch deflection and premature breakage. For a 1.5 mm steel sheet, the smallest hole is 1.5 mm diameter.
2. Space holes at least 2× Materialstärke from each other and from the part edge. Closer spacing causes the web between holes to distort or tear during punching. For 1.0 mm stock, keep holes at least 2.0 mm apart.
3. Inside bend radii should be at least 1× Materialstärke. Tighter radii risk cracking on the outside of the bend, especially with aluminum and stainless. For 5052 aluminum, use 1.5× Materialstärke as the minimum.
4. Keep features at least 3× Materialstärke from bend lines. Holes, slots, and tabs too close to a bend will distort as the material stretches. For a 1.2 mm part, keep features 3.6 mm from any bend.
5. Specify burr direction on the drawing. Every punched edge has a burr on the die side and a clean shear on the punch side. Use an arrow or note (“burr this side”) — this costs nothing but prevents assembly problems.
6. Use full-radius corners (not sharp) on blanked profiles. Sharp internal corners concentrate stress and accelerate die wear. Minimum corner radius = 0.5× Materialstärke for steel, 1× for aluminum.

Stanzen vs. Laserschneiden + CNC-Biegen: Wann umsteigen?

One of the most common questions from buyers is when to move from laser-cut prototypes to Stanzen Produktion. The decision comes down to volume, part complexity, and tolerance requirements:

The crossover point where Stanzen becomes cheaper than Laserschneiden typically falls between 2,000 and 5,000 units, depending on part size and complexity. Below this volume, a good Blechfertigung shop can produce parts economically with Laserschneiden and CNC Biegen — and you avoid the upfront die investment.

Fazit

Blech Stanzen rewards volume and punishes low quantities with tooling amortization. The key to a successful Stanzen project is matching the process to your part: blanking for simple flat parts, progressive die for complex high-volume components, deep drawing for hollow shells. Start with laser-cut prototypes to validate fit and function. Once your design is stable and volumes justify it, transition to Stanzen for the best combination of unit cost, speed, and part-to-part consistency.