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

Electrical connector stamping - precision setup tips?

yuki_rd

We stamp electrical connectors and just moved from a mechanical press to servo. The precision is there but I'm still dialing in the setup. Tips?

**Press Requirements
**
- BDC repeatability: +/-0.005mm or better
- Slide parallelism: 0.005mm per 300mm
- Only direct-drive servo presses can reliably achieve these specs

**Die Requirements
**
- Die clearance: 3-5% of material thickness per side
- Die material: carbide punches and dies
- Guide pins: 0.002mm clearance

**Strip Feed
**
At 400 SPM, feed must advance in under 50ms with +/-0.01mm accuracy:
- Servo feed with closed-loop position control
- Synchronized to press encoder output
- Strip tension control to prevent wander

**Quality Control**

- Vision system in die: check geometry every stroke
- Contact force tester: sample 1 in 1000 parts
- Automatic reject before reel-up

lisaQ_metrology

Connector terminal stamping is where servo presses really earn their premium. We track CPK on terminal width (critical dimension) and consistently get 2.0+ on the press vs 1.3-1.5 on our old mechanical. The BDC repeatability of ?0.005mm is the main driver. At 400 SPM, that's remarkable consistency.

toolndye_dave

Die design for connector stamping on servo presses: use guided strippers with ball-bearing guides, not plain bushings. At 400+ SPM, the stripper cycling generates heat that causes plain bushings to gall. Ball-bearing guides run cooler and last 5x longer. The extra $2,000 per die is nothing compared to the downtime from a seized stripper.

mchen_servo

We do USB-C and automotive connector terminals on a 110T Aida servo, running 350-450 SPM depending on the part. Couple things that took us a while to figure out:

Feed accuracy matters more than press accuracy for connectors. We spent months chasing a dimensional issue that turned out to be 0.008mm of feed inconsistency, not the press. Switched to a servo roll feed with closed-loop encoder feedback and the problem disappeared. The press BDC was fine all along.

Strip guidance through the die is critical at high speed. We use pilot pins on every other station now — used to skip stations to save cost and had strip wander issues above 300 SPM. The extra pilots added maybe $500 to the die but eliminated a scrap problem that was costing us $2K/month.

Temperature control: our die runs about 45C at steady state. If we stop for lunch and restart, the first 50-100 parts are slightly different because the die is cold. We added a die preheater (just a simple cartridge heater in the die shoe) and now we get consistent parts from the first hit. Cost about $300 to add.

pressroom_tom

Following up with more detail on connector stamping since we've been running this for a while now.

The tolerance game on connectors is brutal. We're holding +/-0.015mm on pin spacing for automotive connectors, and the servo press is only part of the equation. Here's what actually controls your precision:

Die temperature stability: connector terminals are typically 0.3-0.8mm phosphor bronze or brass. These thin materials are extremely sensitive to die temperature. A 15C die temperature change shifts your bend angle by about 0.5 degrees on a 90-degree form. On a 3mm leg length, that's 0.026mm of position error — already outside our tolerance. We run die temperature within a 5C band using cartridge heaters and thermocouple feedback to the PLC.

Feed accuracy vs press accuracy: on progressive dies for connectors, your feed system is more important than your press. We use a servo roll feeder with encoder feedback, and the feed accuracy spec is +/-0.01mm. But the real-world accuracy depends on strip tension, pilot pin engagement, and material springback in the feed direction. We added a strip straightener with adjustable roller pressure and it improved feed consistency more than any press parameter change.

Pilot pin strategy: we run pilot pins at every station, not every other station like some shops do for larger parts. The strip is so thin that it can shift laterally between stations if there's any play. The cost of extra pilot pins is trivial compared to the scrap cost of mislocated features.

Speed vs quality tradeoff: we run at 120 SPM on our connector line. The press can do 180 SPM but above 140 SPM we start seeing strip vibration between stations that causes inconsistent pilot pin engagement. The fix would be a vacuum strip hold-down system between stations, but at 120 SPM our quality is where it needs to be and the ROI on the vacuum system doesn't pencil out for our volumes.

One thing specific to servo press on connectors: use the programmable slide motion to add a very short dwell (10-15ms) at BDC on the coining stations. Connectors often have coined features for contact force, and the dwell ensures full material flow into the coin cavity. Without it, the coined area is about 3-5% undersize because the material hasn't fully yielded before the slide reverses.