Open Frame / Frameless AC Motors
Last Updated: January 16, 2025 Reviewed by: Jon Lowy, consulting engineer
Description
Open Frame or Frameless AC Motors are motors that lack the traditional housing, bearings, and end caps found in standard motors. These motors consist of only the essential components: the stator and the rotor. This design allows them to be integrated directly into mechanical assemblies, providing a compact and efficient solution for various applications.
Working Principle
Frameless AC motors operate by utilizing the interaction between the magnetic fields of the stator and rotor to generate torque. The stator contains multiple poles wound with coils, while the rotor is equipped with magnets. When an AC voltage is applied to the stator windings, it creates a rotating magnetic field that induces a current in the rotor. This interaction produces torque, causing the rotor to turn. The absence of a frame and other non-essential components reduces mechanical losses and enhances cooling efficiency, making these motors highly efficient and responsive.
Applications
Frameless AC motors are used in a variety of specialized applications. For example, they are integral to robotic systems, where their high torque-to-inertia ratio and compact size are crucial. They are also used in surgical robotics for precise servo-driven movements in end effectors and robotic joints. Additionally, these motors find applications in the pump industry and in breathing machines, where low noise and high efficiency are essential.
Advantages over other AC Motors
Frameless AC motors offer several advantages over traditional framed motors. They provide significant weight savings and space efficiency, which is particularly beneficial in applications requiring compact and lightweight designs. The high torque-to-inertia ratio and enhanced cooling efficiency result in better performance and reduced mechanical losses. Furthermore, the direct integration into mechanical assemblies simplifies system design and reduces the risk of failure, ultimately lowering overall system costs.
Limitations
Despite their advantages, frameless AC motors have some limitations. The lack of a protective frame makes them more susceptible to environmental factors such as dust and moisture, which can affect their performance and longevity. Additionally, the integration process can be more complex, requiring precise alignment and assembly to ensure optimal performance. These motors may also have lower overload capabilities compared to traditional framed motors due to the reduced amount of iron in the stator.
Considerations
When considering frameless AC motors, several factors should be taken into account. Initial costs may be higher due to the need for precise integration and potential customization. Operating expenses can be lower, however, due to the motor's high efficiency and reduced mechanical losses. Durability may be a concern in harsh environments, so protective measures may be necessary. Accuracy is generally high, making these motors suitable for precision applications. Replacement and maintenance costs can vary depending on the specific application and environmental conditions, but the simplified design can lead to easier maintenance and lower long-term costs.
from Tecnotion
The QMT-HA 385 series redefines what's possible in the same stator size. Delivering up to 41% more performance, it upgrades your machine with minimal mechanical impact. The HA series distinguished itself with an increased rotor height while keeping the outside of the stator equal. With seamless... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 680 VDC; 120V/60Hz; 208-230/240V 60Hz; 460/480V/60Hz
from Tecnotion
The QMT-HA 485 with it's unmatched performance, is Tecnotion's largest high-torque motor. It enables more accuracy or increases machine productivity. The largest QMT-HA 485 series sets the new benchmark, delivering up to 80% more performance with the same stator and rotor footprint. The higher rotor... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 680 VDC; 120V/60Hz; 208-230/240V 60Hz; 460/480V/60Hz
from Tecnotion
The QMT-LA 230 series is designed for seamless integration - whether in existing systems or new setups. Its aluminum housing keeps weight low, boosting dynamics in rotary tables, trunnion tables, or other moving axes. [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 680 VDC; 120V/60Hz; 208-230/240V 60Hz; 460/480V/60Hz
from Tecnotion
The QMT-LA 310 series is one of the most widely used motor series because it is suitable for many applications, from cutting and grinding to metrology and indexing tables. Its high efficiency keeps cooling demand low, making it ideal as a direct replacement in existing machines. With this upgrade,... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 680 VDC; 120V/60Hz; 208-230/240V 60Hz; 460/480V/60Hz
from Tecnotion
The QMT-LA 385 delivers up to 15% more performance in both continuous torque and efficiency, without changing the mounting interface. It raises the standard for torque density in its class. Looking beyond 15%? The QMT-HA 385, with its higher rotor design, takes performance even to the next level. [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 680 VDC; 120V/60Hz; 208-230/240V 60Hz; 460/480V/60Hz
from Tecnotion
The QMT-LA 485 boosts both continuous torque and efficiency by up to 15%, all while keeping the same mounting interface. Thanks to its aluminum housing, this powerhouse is lighter than expected. This low weight makes installation easier and reduces the overall impact on your machine. When 15% isn't... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 680 VDC; 120V/60Hz; 208-230/240V 60Hz; 460/480V/60Hz
from Tecnotion
The QTL 210 series provides more torque than the smaller QTR series. The QTL 210 is the smallest of the QTL range and is available in three heights, 65, 85 and 105 mm. It has a large inner diameter suitable to route multiple cables through, allowing flexibility in the application. It therefore suits... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 680 VDC; 120V/60Hz; 208-230/240V 60Hz; 460/480V/60Hz
from Tecnotion
The QTL 230 is essentially a QTL 210 motor with a cooling ring for high continuous torque even in combination with high duty cycles and dynamic movement profiles. This cooling ring should be closed with the housing, which creates a cooling channel. It will deliver 67-146 Nm continuous torque and... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 680 VDC; 120V/60Hz; 208-230/240V 60Hz; 460/480V/60Hz
from Tecnotion
The QTL 290 expands on the QTL 210 design to meet even higher torque demands. In combination with low induction values and fast response time this series allows for highly dynamic movements. It makes the series ideal for usage in packaging and laser cutting machinery. The motor should be connected... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 680 VDC; 120V/60Hz; 208-230/240V 60Hz; 460/480V/60Hz
from Tecnotion
The QTL 310 series is based on the QTL 290 with the addition of cooling ring. The cooling ring provides bolting holes for easy installation. This cooling ring should be closed with the housing, which creates a cooling channel. The motor is a reliable heavy duty workhorse. Because of the integrated... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 680 VDC; 120V/60Hz; 208-230/240V 60Hz; 460/480V/60Hz
from Tecnotion
The QTL 385 and QTL485 torque motors supersede the QTL-210 -310 series as the biggest torque motors that Tecnotion has to offer. It has the same efficient and space-saving electromagnetic design scaled up for even higher torque demands. With a big inner diameter, it is very suitable to integrate... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 680 VDC; 120V/60Hz; 208-230/240V 60Hz; 460/480V/60Hz
from Tecnotion
The QTR 105 is where the medium-range of Tecnotion QTR motors starts. QTR 105 motors are available with a wide range of options such as different winding types and a digital hall sensor. Various medical and health care applications benefit from the large inner diameter of the QTR 105 as well as the... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 325 VDC / 565 VDC; 120V/60Hz; 208-230/240V 60Hz
from Tecnotion
The QTR 133 is the second medium-range QTR motor. It covers the torque range from 2.6 to 21.9Nm. The largest 60mm high QTR 133-60 motor offers a peak torque of 35.3Nm. Different winding types make the motor suitable for a wide variety of semiconductor and robotics applications for low voltage or... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 325 VDC / 565 VDC; 120V/60Hz; 208-230/240V 60Hz
from Tecnotion
The QTR 160 series is the largest in diameter of the medium QTR motor range-the smallest motor measures just 17 mm in height, with a continuous torque of 4.2 Nm. The largest motor excels with a peak torque of 155.3 Nm. Power and size make that the QTR 160 Series motors can often replace large... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 325 VDC / 565 VDC; 120V/60Hz; 208-230/240V 60Hz
from Tecnotion
The QTR 65 is the smallest torque motor in the Tecnotion torque motor range. This motor is optimized for small and low-voltage applications. With an outer diameter of 65mm and an inner diameter of 17 mm, this motor offers unique opportunities for small applications. The 65 Series is available in... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 565 VDC; 120V/60Hz; 208-230/240V 60Hz
from Tecnotion
The QTR 78 is the second size available in the Tecnotion QTR range. This series offers a continuous torque range from 0.57 to 4.47 Nm. The largest QTR 78-60 motor offers a peak torque of over 7.6Nm. To provide maximum flexibility and integration, the QTR 78 uses flying leads instead of a power... [See More]
- Environmental Features: Open Frame / Frameless
- AC Construction: Synchronous
- Commutation: Brushless
- AC Voltage & Frequency: 565 VDC; 120V/60Hz; 208-230/240V 60Hz
from Kollmorgen Corporation
The KBM ™ Series is designed to be directly embedded in your machine, using the machine ’s own bearings to support the rotor. With a huge selection of standard motors —plus our ability to quickly and cost-effectively incorporate co-engineered modifications —you can choose an... [See More]
- Environmental Features: Open Frame / Frameless
- AC Voltage & Frequency: 208-230/240V 60Hz; 460/480V/60Hz
- Commutation: Brushless
- Output Power: 2 HP; 5 HP / 3.6 KW
from Genesis Motion
The LiveDrive ® LDX is a patented frameless motor with superior torque to length, torque to mass, and motor constant (Km) compared to other direct drive motors. Your machines can accelerate faster, with increased payload, and reduced size/weight. [See More]
- Environmental Features: Open Frame / Frameless
- AC Voltage & Frequency: 208-230/240V 60Hz
- Commutation: Brushless
- Output Power: 0.6567
from Genesis Motion
The LiveDrive ® LDX is a patented frameless motor with superior torque to length, torque to mass, and motor constant (Km) compared to other direct drive motors. Your machines can accelerate faster, with increased payload, and reduced size/weight. [See More]
- Environmental Features: Open Frame / Frameless
- Output Power: 0.6138
- Commutation: Brushless
- Continuous Current: 14.4