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

Servo Press Energy Consumption: How to Calculate and Reduce Operating Costs

admin

Energy cost is a significant factor in servo press economics. A 400-ton servo press running 2 shifts can consume 150,000-200,000 kWh per year. Here is how to calculate and reduce it.

## Understanding Servo Press Energy Flow

Unlike mechanical presses with flywheels, servo presses draw energy directly from the grid on each stroke. The energy profile has three phases:

1. Acceleration phase: high current draw as the slide accelerates
2. Forming phase: peak current at maximum forming force
3. Deceleration/return phase: regenerative braking returns energy to the DC bus

Net energy per stroke = forming energy + friction losses - regenerated energy

## Calculating Energy Per Stroke

Forming energy (joules) = average forming force (N) x forming stroke length (m)

Example: 500 kN average force over 50mm forming stroke
- Forming energy = 500,000 x 0.05 = 25,000 J = 25 kJ per stroke
- At 30 SPM: 25 kJ x 30 = 750 kJ/min = 12.5 kW forming power
- Add 30% for friction and drive losses: 16 kW average
- At 16 hours/day, 250 days/year: 64,000 kWh/year

## Regenerative Energy Recovery

Modern servo presses with regenerative drives return 20-40% of the forming energy back to the grid during deceleration. This is the single biggest energy saving feature.

Verify your drive has regenerative capability:
- Yaskawa: CIMR-AC series with regenerative converter
- Siemens: SINAMICS S120 with Active Line Module (ALM)
- ABB: ACS880 with regenerative supply unit

If your press has a braking resistor instead of regenerative capability, a retrofit can pay back in 2-3 years at high production volumes.

## Practical Energy Reduction Steps

1. Optimize SPM: running at 80% of max SPM often reduces energy by 15-20% due to lower acceleration currents
2. Reduce idle time: program the press to go to low-speed idle mode after 30 seconds without a stroke command
3. Optimize motion profile: minimize unnecessary acceleration/deceleration in the return stroke
4. Maintain power factor: servo drives with poor power factor correction increase apparent power demand
5. Schedule production: run high-energy jobs during off-peak hours if your utility has time-of-use pricing

## Monitoring Energy in Real Time

Most servo press drives expose energy data via fieldbus or HMI:
- Siemens SINAMICS: r0039 (energy consumed), r0041 (energy regenerated)
- Yaskawa: Un0C0 (power consumption monitor)
- ABB ACS880: parameter 01.50 (energy counter)

Log this data to identify which jobs consume the most energy and target them for optimization first.

carlos_stamping

We installed power meters on all 8 servo presses. The data was eye-opening. Our 400T press running blanking at 40 SPM used 22 kWh/shift. The same press running deep draw at 15 SPM used 35 kWh/shift. The forming energy per part was 3x higher on the draw job. Now we schedule energy-intensive jobs during off-peak rate hours.

anna_controls

The regenerative braking efficiency depends heavily on the DC bus capacitor bank size. Larger capacitors store more regenerated energy for the next stroke. On retrofit projects, I always recommend upgrading the capacitor bank —it's a $3,000-5,000 investment that typically reduces energy consumption by 10-15%.