Coreless DC motor
FAULHABER SR (precious-metal commutation) coreless DC motor
Ironless skew-wound brushed DC micromotors with precious-metal commutation and rare-earth magnets, for low-current, battery-friendly precision drives.
Key specifications
| Outer diameter | 8–22 mm |
|---|---|
| Rated torque (max) | 0.01 Nm |
| Speed (max) | 17,000 rpm |
| Voltage | 3-36 V |
Summarised in our own words from Dr. Fritz Faulhaber GmbH & Co. KG's published data; series maxima, individual models vary. Last checked 2026-10-29. Source 1
Notes on this data
Faulhaber lists 'torque up to' per series without saying whether it is continuous or peak; stored as torque_Nm_rated_max (converted from mNm). Related precious-metal lines on the same page: S/G (6-22 mm), SXR (12-16 mm), SR-Flat (15-26 mm, up to 100 mNm).
Specify Motion is not affiliated with Dr. Fritz Faulhaber GmbH & Co. KG. FAULHABER and SR (precious-metal commutation) are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Typical applications
Engineer support
Speak to our engineers about your project
Our experienced engineers are on hand, ready to help with your project. Whether you need the FAULHABER SR (precious-metal commutation) itself, help sourcing it, or a modified or custom design built around your load, speed and space, tell us what the machine has to do and we'll come back with the right option.
- Help sourcing SR (precious-metal commutation) and spares for installed machines
- Modified and custom designs when a catalogue part doesn't fit
- Complete axis: motor, drive, gearing and feedback matched together
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 FAULHABER SR (precious-metal commutation)
Send these with your enquiry and an engineer can confirm the right SR (precious-metal commutation) 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
FAULHABER SR (precious-metal commutation): frequently asked questions
What is the FAULHABER SR (precious-metal commutation)?
Ironless skew-wound brushed DC micromotors with precious-metal commutation and rare-earth magnets, for low-current, battery-friendly precision drives. Published series figures include outer diameter 8 mm, outer diameter 22 mm, rated torque 0.01 Nm, speed 17,000 rpm. It is made by Dr. Fritz Faulhaber GmbH & Co. KG; Specify Motion can help source it or propose an equivalent.
Who makes the FAULHABER SR (precious-metal commutation)?
The FAULHABER SR (precious-metal commutation) is made by FAULHABER (Dr. Fritz Faulhaber GmbH & Co. KG) and is listed here for engineers comparing options. Specify Motion is not affiliated with Dr. Fritz Faulhaber GmbH & Co. KG; brand names are used only to identify the product.
What is the outer diameter of the FAULHABER SR (precious-metal commutation)?
The published series minimum outer diameter is 8 mm. Individual models and sizes in the SR (precious-metal commutation) 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 FAULHABER SR (precious-metal commutation)?
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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Engineer support
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Tell us about your project and how you use the FAULHABER SR (precious-metal commutation): the load, speed, duty and environment. An experienced engineer will review it and reply, normally within one working day.
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