Synchronous torque motor WK series

12 V36 V24 V

Introduction
The external-rotor frameless torque motor is a permanent-magnet synchronous motor (PMSM) composed of an external rotor integrated with the outer shell and an internal stator with copper windings and laminations. The frameless architecture removes housings, bearings and shafts so the rotor can be embedded directly into the driven structure. This enables compact direct-drive integration, effective thermal paths and suitability for low-speed, high-torque applications such as medical devices, industrial fans and automated systems.

Features

• Optimized external-rotor structure - integrated rotor and shell increase rotor inertia, improving low-speed stability and conducting heat through the shell.
• Internal stator placement - reduces electromagnetic interference on the load and supports precision control.
• High torque density and efficiency - multipole permanent-magnet layouts and vacuum potting increase torque density by ~20%-30% and reduce transmission losses.
• Direct-drive dynamic response - eliminates backlash from gears/belts, improving response time and enabling micrometer-level positioning.
• Enhanced thermal management and lightweight design - direct rotor-shell contact and high-conductivity materials improve heat dissipation by ~20%-30% and reduce mass by ~30%-50%.
• Customizable integration - rotor dimensions and magnetic patterns can be tailored for embedding into mechanical structures.
• Quiet operation and low maintenance - absence of mechanical transmission reduces noise (<50 dB) and lowers maintenance frequency.

Specification Table
Key parameters are provided per model in the specification table: nominal voltage, nominal current, nominal torque, nominal speed, max speed, stall torque, stall current, winding turns, phase resistance, phase inductance, speed constant, torque constant, rotor inertia, pole pairs, motor weight, working temperature, max demagnetize temperature. Table values vary by model (see models WK1105 … WK10025).

Characteristics / Technical specifications

• Voltage: mainly 12 V and 24 V (one model at 36 V).
• Nominal torque range: 0.01 N·m to 4 N·m across models.
• Nominal current: typically 0.53 A to 7.4 A (model-dependent).
• Nominal speed: typically ~130 to ~1800 RPM; max speeds vary widely (up to 18057 RPM for high-speed models).
• Operating temperature: -20 °C to 80 °C; max demagnetization temperature: 120 °C.
• Rotor inertia, pole pairs, weight and electrical parameters are specified per model in the table.