How do I size a servo motor for a press application?

Calculate required torque from press tonnage and mechanical advantage, determine speed from target SPM and stroke length, then select a motor with at least 20% margin on both torque and speed. Consider duty cycle and thermal limits.

What is the difference between rated and peak torque for servo motors?

Rated torque is the continuous torque the motor can deliver indefinitely. Peak torque (typically 2-3x rated) is available for short bursts during forming. Press applications need peak torque for the forming stroke and rated torque for the return stroke.

Servo Motor Selector Calculator

Recommend optimal servo motor specs based on load inertia, speed, and acceleration

Load Inertia (kg·m²) ?

Max Speed (rpm) ?

Acceleration Time (s) ?

Deceleration Time (s) ?

Duty Cycle (%) ?

Required Precision (arcsec) ?

Presets:

Motor Sizing Reference

Power Class	Application	Typical Inertia
0.1–0.5 kW	Small assembly, pick-and-place	0.0001 kg·m²
0.5–2 kW	Light stamping, bending	0.0003–0.001
2–5 kW	Medium press, forming	0.005
5–15 kW	Heavy stamping, deep draw	0.02–0.06
15–50 kW	Large transfer press	0.15–0.4

Key Formulas

Required Torque: T = J × ω / t_accel

Required Power: P = T × ω = T × (2π × RPM / 60)

Inertia Ratio: J_load / J_motor — keep below 5:1 for best response

RMS Torque: T_rms = √((T_accel²×t_a + T_load²×t_run + T_decel²×t_d) / t_cycle)

Inertia Ratio Guidelines

< 5:1 — Direct drive OK, easy tuning

5:1 – 10:1 — Tuning difficult, gearbox recommended

> 10:1 — Gearbox required for stable control

Safety Margins

Torque: +20% over calculated peak

Speed: +10% over max required RPM

Thermal: Verify duty cycle < 80% of rated

Servo Motor Selector Calculator

Motor Sizing Reference

Key Formulas

Inertia Ratio Guidelines

Safety Margins

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