What is a servo press?

A servo press uses servo motors for precise force and position control during forming operations.

How do I calculate servo press tonnage?

Use our free tonnage calculator at servopress.club/tonnage-calculator.html

Fine Blanking Tolerances: Achieving ±0.01mm with Servo Press

admin

Fine blanking produces parts with smooth shear faces and tight tolerances in a single press stroke. Servo presses are the preferred platform due to precise force and position control.

## Fine Blanking Fundamentals

Unlike conventional blanking, fine blanking uses three forces simultaneously:
1. **Blanking force** (punch)
2. **Counter force** (counter punch from below)
3. **V-ring force** (stinger ring that clamps material)

The V-ring prevents material flow, creating hydrostatic compression that produces a clean, crack-free shear face.

## Why Servo Press for Fine Blanking

Servo presses allow independent programming of blanking speed (5-15 mm/s), V-ring engagement force, and counter punch pressure throughout the stroke.

## Achieving ±0.01mm Tolerance

**Press requirements:** Slide parallelism <0.005mm, position repeatability ±0.005mm, thermal compensation active.

**Die requirements:** Clearance 0.5% of material thickness, hardened to 60-62 HRC, ground to Ra 0.4μm on cutting faces.

**Process parameters for 3mm steel:**
- Blanking speed: 8 mm/s
- V-ring force: 15-20% of blanking force
- Counter force: 5-10% of blanking force
- Lubrication: EP oil, 50-80 ml/min flood

## Quality Control

Measure rollover depth (<10% of thickness), burnish zone height (>80% of thickness), burr height (<0.05mm). CMM measurement every 500 parts.

## Applications

Fine blanked servo press parts: automotive seat adjusters, transmission components, hydraulic valve bodies, watch components, medical device parts.

dave_toolmaker

Fine blanking die design for servo presses is different from conventional fine blanking. The V-ring geometry can be less aggressive because the servo controls the material flow better. I've been able to reduce V-ring height by 20% on servo presses, which extends V-ring life significantly.

lisa_quality

We run fine blanked gears for transmission components. CPK on the servo press is consistently above 1.67, vs 1.2-1.4 on our old hydraulic fine blanking press. The servo's BDC repeatability of ?0.005mm is the main reason. We can hold ?0.01mm on the part all day long.

mike_chen_eng

Great data on the CPK numbers. We see similar results ??the BDC repeatability is really the game-changer for fine blanking.

One thing I would add: material consistency matters even more with fine blanking on servos. We had a batch of AISI 1075 that was within spec on hardness but had inconsistent grain structure. The servo press held its position perfectly, but we still got micro-fractures on the shear face. Switched suppliers and the problem disappeared.

Also worth noting ??if you are running progressive fine blanking, the servo lets you program different velocities for each station. We run the piercing stations faster and slow down for the final blank. Adds maybe 5% cycle time but the edge quality improvement is significant.

Anyone here running fine blanked parts thicker than 8mm on a servo? Curious about force requirements at that range.