Frameless Motors

Frameless motors is a type of motor that eliminates the traditional motor housing, consisting solely of a stator assembly (core + windings) and a rotor assembly (permanent magnets + rotor yoke), which are directly integrated into the bearings and housing of the user’s machinery. This “motor-as-a-component” design philosophy integrates the motor with the load, eliminating intermediate transmission components such as couplings and gearboxes, and enabling zero-backlash direct-drive transmission.

Industrial Applications

Collaborative Robots:
Precision Machine Tools:
Aerospace:
Industrial Automation:
Medical Devices:

Frameless motors typically employ a permanent magnet synchronous motor topology, with the stator featuring either concentrated or distributed windings, and the rotor incorporating surface-mounted permanent magnets or an embedded magnetic circuit design. Since there is no separate housing, heat is conducted directly through the outer circumference of the stator to the mounting structure, placing higher demands on system-level thermal management. This design has the following characteristics:

1. High power density: By eliminating the housing and transmission components, volume utilization increases by 30%–50%, and weight is significantly reduced.
2. Zero-backlash drive: The direct-drive configuration eliminates gear backlash, achieving positioning accuracy at the arcsecond level, making it suitable for high-precision servo applications.
3. Excellent dynamic response: Low rotor inertia and a small electrical time constant result in dynamic response frequencies far exceeding those of conventional motors.
4. Flexible thermal management: The stator windings are directly embedded in the mechanism, enabling efficient heat dissipation via the housing or coolant.
5. Highly integrated and customizable: Dimensions and interfaces can be customized as needed to fit the structural space of different devices.

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Frameless Motors Features

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Benefits of Frameless Motors

Frameless Motors feature several key characteristics and components that enable them to operate efficiently and reliably in specialized industries. Let’s explore a few of these key aspects below.

High Power Density

By eliminating the housing and transmission components, volume utilization is increased by 30%–50%, and weight is significantly reduced

Zero-Backlash Drive

The direct-drive design eliminates gear backlash, achieving positioning accuracy down to the arcsecond level, making it suitable for high-precision servo applications

Excellent Dynamic Response

With low rotor inertia and a small electrical time constant, the dynamic response frequency far exceeds that of conventional motors

Flexible thermal management

The stator windings are directly embedded in the mechanism, enabling efficient heat dissipation via the housing or coolant

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Frameless Motors Technical Data

Electrical Specifications	Electrical Parameter Range	Note
Stator Outer Diameter	60mm - 200mm	A series covering low-power to medium- and high-power applications
Rated Power	50W - 3000W	Varies depending on size and cooling method
Rated Speed	20mm - 80mm	High-speed or low-speed versions are available upon request
Peak Torque	1 – 200 N·m	Short-term overloads can reach 3 to 5 times the rated value
Winding Type	Concentrated windings / Distributed windings	High slot fill factor for concentrated windings; low harmonics for distributed windings
Pole-to-Slot Fit	12 slots, 10 poles / 24 slots, 20 poles	Common Fractional Slot Concentrated Winding Configurations
Insulation Class	Class F (155°C) / Class H (180°C)	Supports special insulation for high-vacuum environments
Protection Rating	IP54 ~ IP65	It depends on the integration method and seal design

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Wheatstone Frameless Motors Structure

Wheatstone Frameless Motors

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Wheatstone Frameless Motors Catalogue

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If there is anything you're not sure about or you just need a hand getting set-up you can call or email us.

About Wheatstone:Your Expert Of Frameless Motors

Jiangsu Wheatstone Electric Technology Co., Ltd. is located in Jiangsu Province, adjacent to Shanghai and Wuxi. The company operates two factories, one in Changzhou and the other in Wuxi.

The company primarily manufactures frameless motors, axial flux motors, explosion-proof servo motors, submersible motors, explosion-proof motors for underground coal mines, radiation-resistant motors, and AC/DC servo motors.

If you have any needs regarding custom frameless motors, please feel free to contact us at any time.

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Why Choose Frameless Motors From Wheatstone?

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Quality

Wheatstone is known for delivering high-quality products and services that meet or exceed our customers' expectations.

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Reliability

Our products and services are designed to be reliable, which is why our customers trust us to provide them with solutions that work.

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Innovation

Wheatstone is always at the forefront of new technology and innovation, providing our partners with cutting-edge solutions that keep them ahead of the competition.

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Customization

We understand that every customer's needs are different, which is why we offer customized solutions that meet their specific requirements.

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Experience

Wheatstone has been in the motor industry for many years, and our experience has helped us to develop a deep understanding of the challenges that our customers face.

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Global Reach

We have a strong global presence, with partners in over 70 countries, which enables us to provide our customers with support wherever they need it.

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Commitment to Service

Our commitment to providing exceptional service is at the heart of everything we do, and our partners appreciate the support we provide throughout the entire customer journey.

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Cost-effectiveness

Wheatstone offers cost-effective solutions that provide our customers with the best value for their investment, ensuring that they receive a high return on their investment.

Axial Flux Motors FAQ

Q Frameless Motors FAQ

A 1. Why use a frameless motor?

The biggest difference between frameless motors and traditional motors is that frameless motors lack a housing, shaft, and bearings, consisting solely of two core components: the stator and the rotor.
This design offers several significant advantages:

1.Extremely compact, saving space

2.Enhanced performance and elimination of backlash

3.Greater adaptability to various environments

2.What are the most important considerations when installing and using frameless motors?

Frameless motors require a high degree of installation precision; if certain details are not handled properly, performance will be significantly compromised.

Inst allation precision is key: During installation, both the axial alignment error and coaxiality between the stator and rotor must be controlled within 0.1 mm.

You’ll need to configure the encoder yourself: The frameless motor itself generally does not come with an encoder; it is merely a motor core.

Installation orientation matters: An engineer once asked whether installing the stator and rotor in reverse (with the polarity reversed) would affect performance. Experience shows that as long as the relative axial position and clearance between the two remain unchanged, the only effect is a possible change in the direction of rotation; other electrical parameters remain largely unaffected.