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

How to Read a Servo Press Tonnage Monitor: Complete Guide

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## What the Tonnage Monitor Measures

A servo press tonnage monitor measures the actual forming force during each stroke using strain gauges mounted on the press frame or slide. The reading tells you:

- Whether the die is working correctly
- Whether material thickness is consistent
- Whether a double blank has entered the die
- Whether a punch has broken

## Reading the Display

Most tonnage monitors show:
- **Peak tonnage:** maximum force during the stroke (in tons or kN)
- **Tonnage curve:** force vs. position graph for the full stroke
- **High/low limits:** alarm thresholds

## Setting Limits Correctly

**High limit:** Set at 110-115% of nominal tonnage. This catches:
- Double blanks (two sheets entered die)
- Die crash (foreign object in die)
- Incorrect material (wrong thickness or grade)

**Low limit:** Set at 80-85% of nominal tonnage. This catches:
- Missing blank (no material in die)
- Broken punch (punch not forming)
- Incorrect material (too thin)

## Interpreting Tonnage Curves

**Normal curve:** Smooth rise to peak at BDC, then rapid drop on return.

**Double peak:** Two force peaks in one stroke — indicates progressive die with two forming stations, or a problem with die timing.

**Early peak:** Force peaks before BDC — punch hitting material too early, check die setup and material thickness.

**Gradual increase over time:** Die wear or material hardness increasing. Schedule die maintenance.

## Calibration

Calibrate tonnage monitor annually using a reference load cell. Accuracy should be within +/-2% of full scale.

lisa_quality

The tonnage signature shape tells you more than the peak number. A healthy blanking signature has a sharp rise, a peak, and a sharp drop. If the drop becomes gradual, the punch is getting dull. If the peak increases over time, the material is getting harder or thicker. We review signatures weekly as part of our SPC program.

tom_pressops

As an operator, the tonnage monitor is my best friend. I can tell within 5 strokes if something is wrong just by glancing at the waveform. A double peak means a misfeed. A low peak means a missed hit. A gradually rising peak means the die needs sharpening. Once you learn to read it, you catch problems before they become scrap.