In motion control, motor architecture defines the limits of precision, efficiency, and responsiveness. While traditional iron-core motors dominate commodity applications, maxon’s commitment to high-performance design has led them to focus almost exclusively on coreless DC motor architecture. Here's why.
What Is a DC Coreless Motor?
Coreless motors eliminate the traditional iron laminated stator core found in iron-core motors. Instead, the rotor windings are formed in a self-supporting, skew-wound basket coil, held together with epoxy or a similar material.
The permanent magnets are positioned around the rotating coil, and the absence of iron in the rotor drastically reduces mechanical inertia.
Iron-Core Motors: Limitations in Precision
Iron-core DC motors use a laminated steel core wound with copper wire. While cost-effective and robust for general-purpose use, this design introduces performance-limiting characteristics:
- Cogging Torque: Magnetic detents occur as rotor teeth align with stator slots, causing uneven motion at low speeds.
- Higher Rotor Inertia: The mass of the iron core increases response lag and overshoot in dynamic systems.
- Eddy Current and Hysteresis Losses: Laminated cores still exhibit magnetic losses, reducing efficiency in continuous operation.
The maxon Advantage: Why Coreless?
maxon’s coreless brushed and brushless DC motors are engineered for demanding applications in robotics, medical devices, aerospace, and precision automation. Their adoption of coreless rotor technology delivers multiple performance advantages:
- Zero Cogging Torque - With no iron in the rotor, maxon coreless motors offer smooth, precise motion—even at very low speeds. This is particularly critical in applications such as surgical robots, valve actuators, or optical stages, where precise micro-positioning is required.
- Ultra-Low Rotor Inertia - The lightweight winding structure allows for rapid acceleration and deceleration. This translates to faster response times, tighter control loops, and reduced overshoot in servo applications.
- High Efficiency - Reduced magnetic losses and optimized coil design result in motor efficiencies up to 90%. Less heat means smaller motors can be used for the same power output, ideal for size- or weight-constrained systems.
- Linear Torque-to-Current Characteristics - Coreless designs produce a predictable, stable torque curve with minimal ripple, improving control in dynamic feedback environments.
Where Iron-Core Still Has a Role
Iron-core motors are still appropriate for low-cost, high-volume applications where fine control isn’t a priority—such as small fans, pumps, or consumer-grade motion systems. Their mechanical simplicity makes them suitable when efficiency and smooth motion are not critical.
Typical Applications of DC Coreless Motor Architecture
Medical Devices
- Infusion and insulin pumps – quiet, low-vibration operation
- Surgical power tools – high power-to-size ratio
- Prosthetics and orthotics – smooth motion and compact integration
- Dental instruments – low noise, high speed, and sterilizability
Aerospace & Defense
- Satellite antenna actuators – lightweight and reliable in vacuum
- UAVs and drones – fast response and high torque density
- Missile fin actuation systems – extreme reliability under dynamic conditions
Robotics & Automation
- Humanoid and service robots – smooth joint actuation with precise control
- Autonomous inspection tools – lightweight with efficient power draw
- Surgical robots – accurate and responsive micro-movement
Precision Industrial Equipment
- Optical systems – focus and zoom lens drive mechanisms
- Semiconductor handling tools – fast positioning with minimal vibration
- Microfluidics – precise control of small flow volumes
Instrumentation & Lab Automation
- Analytical devices – reliable and repeatable motion
- Sample positioning stages – consistent speed and accuracy
- Pipetting systems – fine control in compact form factors
maxon’s decision to focus on coreless motor technology is rooted in physics, not trend. By eliminating iron from the rotor, a platform for smooth, efficient, high-performance motor control is achieved. For engineers requiring motors with high dynamics, coreless motor technology is not a luxury—it’s a requirement.
