HONPINE JM Fourth-Generation Frameless Torque Motor: 30% Higher Torque Density and 10% Lower Operating Temperature

Recently, the HONPINE frameless torque motor successfully completed trial applications in a surgical robot, demonstrating excellent electromagnetic performance and motion stability. During testing, the motor achieved torque ripple of less than 1%, significantly below the commonly referenced 2% target for surgical robotic motors, where excessive torque fluctuations can cause vibration and affect precise surgical operations.

Low torque ripple is essential for surgical robots, as it helps minimize unwanted vibration, improve motion smoothness, and ensure consistent reproduction of precise surgical movements.

So, how does the HONPINE JM fourth-generation frameless torque motor achieve smoother low-speed operation, lower iron losses at high speeds, and improved overall thermal performance?

In this article, we explore its key technological improvements in electromagnetic design, material selection, and winding processes.

1. What Are the Key Technological Improvements in the HONPINE JM Fourth-Generation Frameless Torque Motor?

The HONPINE JM fourth-generation frameless torque motor incorporates comprehensive improvements across four key areas: magnetic circuit design, pole-slot combination, material selection, and winding technology.

These optimizations improve electromagnetic energy conversion efficiency, increase torque density, reduce power losses, and control temperature rise, enabling stable and efficient operation across a wide range of working conditions.

Optimized Electromagnetic Design

Through an optimized pole-slot combination, the motor achieves a higher winding factor, improving electromagnetic utilization and torque output.

The motor also adopts a large-stator-bore and large-inner-diameter rotor configuration, balancing high torque density with lightweight construction while providing greater flexibility for compact equipment integration.

In addition, HONPINE has optimized the magnetic air gap and the topological geometry of the stator and rotor. These improvements reduce cogging torque to approximately 1% of rated torque, helping minimize torque fluctuations during low-speed operation.

The back EMF harmonic distortion rate is also controlled to within 1%, further improving electromagnetic consistency and motion smoothness.

2. How Does the Motor Achieve a 10% Reduction in Operating Temperature?

Thermal management is a critical consideration for frameless torque motors, particularly in compact robotic joints and precision equipment where installation space is limited and heat dissipation can be challenging.

The HONPINE JM fourth-generation motor reduces operating temperature by optimizing core materials, permanent magnets, insulation systems, and winding processes.

High-Grade Electrical Steel for Lower Iron Losses

Both the stator and rotor use 0.2 mm high-grade non-oriented electrical steel. The thinner laminations help reduce eddy current losses, while the material's magnetic properties support higher magnetic flux density under comparable operating conditions.

This allows the motor to deliver greater electromagnetic output while reducing iron losses, particularly during high-speed operation.

High-Performance Permanent Magnets for Demanding Operating Conditions

The motor uses high-grade UH-series permanent magnets featuring high remanence, high coercivity, and excellent temperature resistance.

These properties help maintain magnetic performance under high-temperature conditions and reduce the risk of irreversible demagnetization.

To address the limited installation space of frameless motors, HONPINE has also optimized the magnet dimensions and magnetic circuit layout. This compact design maintains efficient output under high-speed, high-torque, and high-overload operating conditions.

High-Temperature Insulation Materials for Long-Term Reliability

The insulation system meets Class F or higher temperature-resistance requirements, with a thermal rating above 150°C.

Key components, including permanent magnets, electromagnetic wires, insulation bobbins, and impregnation materials, are selected for temperature resistance of up to 180°C.

These material specifications support long-term operation in demanding thermal environments and help meet the continuous operating requirements of robotic systems.

Advanced Winding Technology for Lower Copper Losses

The HONPINE JM fourth-generation motor adopts an automated multi-slot continuous winding process, achieving a slot fill factor of up to 80%.

A higher slot fill factor reduces winding resistance and copper losses under comparable torque conditions, helping control temperature rise while improving overload capability.

The automated winding process also reduces the number of solder joints, contributing to improved electrical connection reliability and overall motor consistency.

By combining electromagnetic optimization, advanced materials, and automated manufacturing processes, HONPINE delivers a frameless torque motor designed for high-performance robotic applications, including humanoid robots, surgical robots, and precision automation equipment.

3. Multiple Models and Flexible Configuration Options

To meet the different torque and speed requirements of robotic joints and precision motion systems, HONPINE offers a range of frameless torque motor models with multiple speed configurations.

The standard product range covers motor outer diameters from 38 mm to 140 mm, with high-, medium-, and low-speed configurations available.

The torque range is approximately 3 Nm to 13 Nm, depending on the model and operating conditions.

Optional configurations include Hall sensors and temperature sensors, allowing customers to select suitable feedback and temperature-monitoring solutions according to their application requirements.

These configuration options make the HONPINE JM frameless torque motor suitable for integration into robotic joints, surgical robotic systems, precision positioning equipment, and other compact direct-drive applications.

4. JM Second-Generation vs. Fourth-Generation Frameless Torque Motor: What Has Changed?

To better understand the performance improvements, let's compare the HONPINE JM second-generation and fourth-generation frameless torque motors using a motor with an outer diameter of 38 mm and an iron core length of 6 mm as an example.

Performance Comparison of JM Second-Generation and Fourth-Generation Motors

The comparison highlights the improvements achieved through electromagnetic design, material upgrades, and manufacturing process optimization.

Note: Insert verified test data for both generations in the comparison table. Ensure that torque, speed, temperature rise, and other performance parameters are measured under equivalent test conditions.

5. Automated Manufacturing for Consistent Motor Quality

The HONPINE frameless torque motor series has entered automated mass production.

Automated manufacturing helps ensure stable production capacity while maintaining strict control over dimensional tolerances and manufacturing precision.

Combined with optimized production processes and quality inspection procedures, this supports consistent product performance and manufacturing reliability, helping reduce component selection and integration risks for customers.

As demand for high-performance motion control continues to grow in robotics, medical equipment, and precision automation, HONPINE remains committed to improving frameless torque motor technology.

Looking for a High-Torque-Density Frameless Motor for Your Application?

Contact HONPINE to request the latest technical specifications and product information for the JM fourth-generation frameless torque motor.