Coreless DC motor
maxon EC-max coreless DC motor
Economical brushless motors with ironless winding and preloaded bearings, offered in small diameters.
Key specifications
| Outer diameter | 16–22 mm |
|---|---|
| Continuous torque (max) | 0.011 Nm |
| Speed (max) | 18,000 rpm |
| Power (max) | 12 W |
Summarised in our own words from maxon group (maxon motor ag)'s published data; series maxima, individual models vary. Last checked 2026-10-29. Source 1 · Source 2
Notes on this data
Only EC-max 16 and EC-max 22 appear in the 2026/27 table of contents; maxima from EC-max 22 (12 W, ~11 mNm, 18,000 rpm). EC-max 16 page not read. EC-4pole not located in the 2026/27 TOC.
Specify Motion is not affiliated with maxon group (maxon motor ag). maxon and EC-max are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Typical applications
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What a coreless DC motor is
A coreless DC motor has a self-supporting rotor winding with no iron core, typically arranged as a skewed or rhombic basket that spins around a fixed magnet. Without iron in the rotor, there is no cogging, inertia is very low and inductance is small, giving fast acceleration, smooth low-speed running and high efficiency. Coreless designs exist in brushed form, with precious-metal or graphite commutation, and in brushless form. They are usually small, from a few millimetres to tens of millimetres across.
When engineers choose a coreless DC motor
Choose a coreless motor for compact, high-efficiency, highly dynamic drives such as medical devices, surgical tools, laboratory instruments, optics and robotics. Low inertia and no cogging suit smooth precise motion. The trade-offs are thermal capacity and cost: the light winding heats quickly under overload, and coreless motors cost more than iron-core brushed motors. For high continuous torque in a larger size, an iron-core or brushless motor may be more economical.
How to specify the maxon EC-max
Send these with your enquiry and an engineer can confirm the right EC-max variant or an equivalent:
- Diameter and length (mm)
- Supply voltage (V)
- Continuous and stall torque (mNm)
- Speed range (rpm)
- Commutation: precious metal, graphite or brushless
- Gearhead and encoder options
- Life and duty cycle
Common mistakes to avoid
- Overloading briefly and overheating the low thermal mass winding
- Choosing precious-metal brushes for high-current start-stop duty
- Ignoring gearhead efficiency and life
- Running without current limiting
maxon EC-max: frequently asked questions
What is the maxon EC-max?
Economical brushless motors with ironless winding and preloaded bearings, offered in small diameters. Published series figures include outer diameter 16 mm, outer diameter 22 mm, continuous torque 0.011 Nm, speed 18,000 rpm. It is made by maxon group (maxon motor ag); Specify Motion can help source it or propose an equivalent.
Who makes the maxon EC-max?
The maxon EC-max is made by maxon (maxon group (maxon motor ag)) and is listed here for engineers comparing options. Specify Motion is not affiliated with maxon group (maxon motor ag); brand names are used only to identify the product.
What is the outer diameter of the maxon EC-max?
The published series minimum outer diameter is 16 mm. Individual models and sizes in the EC-max range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
Is there an alternative to the maxon EC-max?
Yes. Our engineers can propose an equivalent built around your load, speed and environment. An engineer confirms the fit against your application before recommending anything.
What are the advantages of a coreless DC motor?
With no iron in the rotor, coreless motors have no cogging, very low rotor inertia and low inductance. This gives smooth running, fast acceleration and high efficiency. They suit compact, battery-powered and precise applications. The trade-off is limited thermal mass, so overloads must be controlled.
Should I choose precious-metal or graphite brushes?
Precious-metal brushes give low friction and low electrical noise, which suits low current, continuous running and battery devices. Graphite brushes handle higher currents and frequent start-stop duty better. Choose by current level and duty cycle, or move to a brushless coreless design for longer life.
Further reading: How to select a dc motor · Servo and stepper motors
Other coreless dc motor series
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Tell us about your project and how you use the maxon EC-max: the load, speed, duty and environment. An experienced engineer will review it and reply, normally within one working day.
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