Manufacturing Process
Fine Blanking
精冲
High-precision blanking with a V-ring impingement to produce smooth, near-shear edges and tight dimensional control in one stroke.
Process Steps
- Strip fed into fine blanking press
- V-ring and counter punch engage
- Part and slug separated
- Edge quality inspected
What is fine blanking?
Direct answer: fine blanking is a single-stroke process that produces a part with a smooth, near-vertical sheared edge instead of the fractured edge an ordinary blanking die leaves. Three forces act at once: a V-ring impingement ring presses into the strip, a counter-punch holds the part flat, and the punch shears it. Because the material is clamped in all three directions, it shears rather than tears.
What it holds
| Property | Typical |
|---|---|
| Dimensional tolerance | ±0.01–0.03 mm |
| Smooth shear zone | 80–95 % of the material thickness |
| Flatness | Better than 0.02 mm is achievable |
| Edge finish | Ra 0.4–1.6 µm on the sheared face |
| Hole position, one stroke | Set by the tool, typically ±0.02 mm |
When fine blanking earns its cost
- The edge is functional: a lever, a ratchet face, a gear sector, a part that runs against another part.
- The drawing would otherwise need shaving, milling or grinding after blanking — fine blanking deletes that operation and the chip waste with it.
- The part is thick relative to its outline, where ordinary blanking produces a pronounced fracture zone.
- The part must be flat, for example a valve plate or a sensor component that seats on a face.
The trade is straightforward: a fine-blanking tool costs more than a conventional blanking tool, and the press needs the V-ring and counter-punch forces. It pays back as soon as it replaces one secondary operation at volume.
Design rules that matter
- No razor-sharp corners. The tool has to shear cleanly at every corner; a small radius is easier to hold than a knife edge.
- Minimum web and edge widths roughly equal to the material thickness, so the V-ring has material to bite into.
- Material matters. Fine blanking likes a spheroidise-annealed, low-carbon or alloy steel with good ductility; very hard or heavily work-hardened stock fights the process.
- Holes close to the edge are easier in fine blanking than in conventional blanking, but the same rule applies: leave the tool some material to work with.
Frequently asked
How is fine blanking different from normal blanking?
A conventional die shears the strip and the edge has a rollover, a burnish band and a fracture zone. Fine blanking clamps the material with a V-ring and a counter-punch so it shears cleanly over most of the thickness, which also removes the need for shaving.
Does fine blanking remove the need for deburring?
It reduces the burr to a fraction of what ordinary blanking leaves, but a light deburr is still normal before plating or assembly.
Can fine blanking replace machining?
Often, for flat parts: a fine-blanked plate or lever can be used as sheared, with no milling of the profile. Where a bore or a face has to be truly cylindrical, machining still wins.
Is fine blanking suitable for deep-drawn parts?
No — it is a cutting process. But a fine-blanked flat blank is an excellent starting point for a later drawing operation, and the two are often used in the same route.
Related: blanking · precision stamping · precision metal stamping · deburring · deep drawing