Frameless torque motor
HIWIN TM-2 / IM-2 torque motors
Water-cooled frameless torque motor components with stator diameters from 160 to 565 mm; TM-2 series maximum 3,375 Nm continuous and 6,000 Nm peak, IM-2 high-speed variant to 5,450 rpm with field weakening.
Key specifications
| Outer diameter | 160–565 mm |
|---|---|
| Peak torque (max) | 6,000 Nm |
| Continuous torque (max) | 3,375 Nm |
| Speed (max) | 5,450 rpm |
| Cooling | water cooled |
Summarised in our own words from HIWIN Technologies Corp.'s published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1
Notes on this data
TM-2 succeeds TMRW. 5,450 rpm is IM-2; TM-2 maximum listed 3,338 rpm at continuous torque (TM-2-13-SA0). Peak torque for 1 s.
Specify Motion is not affiliated with HIWIN Technologies Corp.. HIWIN and TM-2 / IM-2 torque motors are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Typical applications
Engineer support
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Our experienced engineers are on hand, ready to help with your project. Whether you need the HIWIN TM-2 / IM-2 torque motors 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 TM-2 / IM-2 torque motors 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 frameless torque motor is
A frameless torque motor is a permanent-magnet brushless motor supplied as two parts, a rotor and a stator, with no housing, bearings or shaft. The machine builder mounts the rotor directly on the driven shaft and the stator in the machine structure, so the motor becomes part of the mechanism. Many have large through-holes and high pole counts, giving high torque at low speed with no gearbox. They need separate feedback, typically an encoder, and a servo drive.
When engineers choose a frameless torque motor
Choose a frameless motor when you want direct drive in a compact, integrated design, such as robot joints, gimbals, rotary tables and medical devices. Removing the gearbox eliminates backlash and improves stiffness and smoothness. The trade-offs are integration work and size: the builder supplies bearings, alignment, cooling and feedback, and torque per volume is lower than a geared solution. For off-the-shelf installation, a housed direct-drive motor may be simpler.
How to specify the HIWIN TM-2 / IM-2 torque motors
Send these with your enquiry and an engineer can confirm the right TM-2 / IM-2 torque motors variant or an equivalent:
- Continuous and peak torque (Nm)
- Speed (rpm)
- Outer diameter, bore and stack length (mm)
- Bus voltage and current (V, A)
- Thermal mounting and cooling
- Feedback type and resolution
- Air gap and concentricity tolerance (mm)
Common mistakes to avoid
- Leaving air gap and concentricity tolerances undefined
- Ignoring heat conduction from the stator into the housing
- Using an encoder with too low resolution for direct drive
- Forgetting rotor magnet attraction during assembly
HIWIN TM-2 / IM-2 torque motors: frequently asked questions
What is the HIWIN TM-2 / IM-2 torque motors?
Water-cooled frameless torque motor components with stator diameters from 160 to 565 mm; TM-2 series maximum 3,375 Nm continuous and 6,000 Nm peak, IM-2 high-speed variant to 5,450 rpm with field weakening. Published series figures include outer diameter 160 mm, outer diameter 565 mm, peak torque 6,000 Nm, continuous torque 3,375 Nm. It is made by HIWIN Technologies Corp.; Specify Motion can help source it or propose an equivalent.
Who makes the HIWIN TM-2 / IM-2 torque motors?
The HIWIN TM-2 / IM-2 torque motors is made by HIWIN (HIWIN Technologies Corp.) and is listed here for engineers comparing options. Specify Motion is not affiliated with HIWIN Technologies Corp.; brand names are used only to identify the product.
What is the outer diameter of the HIWIN TM-2 / IM-2 torque motors?
The published series minimum outer diameter is 160 mm. Individual models and sizes in the TM-2 / IM-2 torque motors 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 HIWIN TM-2 / IM-2 torque motors?
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 is the difference between a frameless and a housed torque motor?
A frameless motor is only a rotor and stator; the machine provides bearings, shaft, housing and feedback. A housed direct-drive motor adds bearings, housing and encoder in a ready-to-install unit. Frameless suits compact, integrated designs where the machine already has stiff bearings; housed suits faster installation and simpler alignment.
Why use a frameless motor instead of a gearbox?
Direct drive removes backlash, wear and compliance in the gear train, giving smoother motion and stiffer control. It also allows a large hollow shaft for cabling. The trade-off is that torque must come from the motor alone, so it is larger for a given torque.
Further reading: How to select a frameless torque motor · Frameless motor sizing robot joints · Frameless and torque motors
Other frameless torque motor series
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Tell us about your project and how you use the HIWIN TM-2 / IM-2 torque motors: the load, speed, duty and environment. An experienced engineer will review it and reply, normally within one working day.
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