Discover how ATEK Drive Solutions enables stutter-free positioning and maximum running smoothness with innovative servo motors.
What is meant by cogging torque (detent torque) in servo motors?
Cogging torque, also known as detent torque, is a unwanted stuttering of the motor when it is in a powered-off state. It arises from the magnetic interaction between the rotor’s permanent magnets and the teeth of the stator. This stuttering can affect the precision of positioning, especially during slow movements, and for instance, in CNC machines, reduce accuracy by up to 5%, if not minimized.
Why is low cogging torque critical for smooth positioning?
A smooth and even positioning is critical in many precision applications such as semiconductor manufacturing, optical systems, or medical technology, where even minimal vibrations can lead to scrap or malfunctions. Servo motors with low cogging torque enable the necessary continuous and vibration-free movement, which improves product quality and can typically reduce error rates by 2-3%..
How is low cogging torque technically realized in servo motors?
Low cogging torque is achieved through targeted design strategies in the motor construction. Key methods include chamfering of the stator slots (can reduce the detent torque by over 70%), an optimized shape and arrangement of the magnets (e.g., segmentation that can reduce harmonics by up to 15 dB) and the use of special magnetic materials with high permeability and low hysteresis losses.
What main advantages do servo motors with low cogging torque offer?
They enable a significantly more precise motion control and repeat accuracy, which can reduce the scrap rate in production processes by up to 5%.. The quieter operation leads to less wear on the motor and mechanics, which can extend the lifespan of the drive unit by 10-15%.. Furthermore, overall performance is improved in demanding applications, for example, by an optimization of cycle times by up to 8% in robotics.
For which applications are servo motors with low cogging torque particularly suitable?
They are ideal for all areas that require maximum precision, smooth operation, and gentle motion guidance. Typical examples include optical inspection systems, lens focusing in cameras, high-precision robotics and automation tasks, medical technology (e.g., imaging techniques), printing machines, machine tools as well as testing and measurement setups..
How do servo motors with low cogging torque differ from standard servo motors?
While standard servo motors are already known for their precision, models with low cogging torque provide a superior smoothness and uniformity of motion, especially at very low speeds and in applications that require frequent start-stop cycles. This can improve the uniformity of motion by up to 50% compared to standard servos without special anti-cogging measures.
Are servo motors with low cogging torque better than stepper motors for smooth positioning?
For very smooth and continuous movements, they are often the better choice. Stepper motors position in discrete steps and have an inherent detent torque, which can lead to microvibrations. Servo motors with low cogging provide a higher dynamics (achieving speeds 3-5 times higher), a continuous motion without step losses thanks to closed-loop control and a more effective compensation for disturbances..
What role do high-resolution feedback systems play in these motors?
High-resolution feedback systems (encoders) are critical to fully exploit the potential of servo motors with low cogging torque. They provide the servo controller with extremely precise information about rotor position. This allows the controller to effectively compensate for even the slightest remaining cogging and other disturbances, ensuring an extremely smooth and accurate positioning. Encoders with over 20 bits of resolution per revolution can improve the positioning accuracy by a factor of 2-4..
Servo motors with low cogging torque enable a significantly smoother and more precise positioning.This is critical for high-quality results in demanding applications and can reduce scrap rates by up to 5%. as well as visibly increase the product quality..
Through innovative design strategies such as stator chamfering (detent torque reduction >70%), optimized magnet arrangements, and special materials, the disturbing cogging torque is minimized. This leads to a superior uniformity of motion und and higher system efficiency..
The use of these special motors results in concrete operational advantages: an extension of the lifespan of the drive components by 10-15% and an improvement of cycle times by up to 8%, especially in robotics, automation, and medical technology.Learn all about the advantages of servo motors with low cogging torque for demanding positioning tasks. From how they work to ideal application areas – this article provides you with all the answers.
In demanding applications where maximum precision and running smoothness are essential, servo motors with low cogging torque are the ideal choice. They minimize unwanted vibrations and ensure stutter-free positioning. Need a custom drive solution? Contact us at ATEK Drive Solutions.
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Understand: What defines servo motors with low cogging torque
Precision and smoothness are often critical for machines. Servo motors with low cogging torque are ideal for applications that require a smooth positioning and offer significant advantages here. This article explains the fundamentals, technology, and selection criteria of these special motors to support solution finding.
Cogging torque simply explained
Cogging torque (detent torque) describes a stuttering motor behavior due to magnetic interaction between rotor and stator, which affects the ability to achieve a smooth positioning. It can reduce precision, e.g., in CNC machines, by up to 5% if not minimized. Details at Details unter More about servo motors.
The importance of smooth positioning in precision applications
Smooth positioning is critical in semiconductor manufacturing or optics, where vibrations mean scrap. Motors with low cogging torque enable the necessary continuous and even movement. Reduced cogging torque improves product quality, often measurable by 2-3% lower error rates. Specialized high-precision gear boxes are suitable for this.Optimize: Technical tips for minimizing detent torque.
Design strategies to minimize cogging torque
Ein Servo motor with low cogging torque benefits significantly from intelligent design strategies. Chamfering the stator slots is one method to reduce torque fluctuations and promote a smooth positioning uniform motion. Optimal chamfering depends on the number of pole pairs and requires FEA simulation for, e.g., over 70% detent torque reduction.
Optimization of magnet arrangement
The arrangement of magnets is essential for low detent torque. Precise shaping and placement of rotor magnets influence magnetic forces and thus the uniformity of motion. Segmentation of magnets smooths the torque curve, which is crucial for smooth positioning and can reduce harmonics by up to 15 dB. Relevant for brushless servo motors, which are often chosen for precise applications.
Use of special magnetic materials
Suitable magnetic materials for rotor and stator are fundamental for Servo motors with low cogging torque; high permeability and low hysteresis losses are advantageous. Powder coating of the stator sheets can minimize eddy current losses, improve running smoothness – a key factor for smooth positioning – and increase efficiency by 1-2%. For demanding environments, micro gear boxes.Benefit: Realizing advantages through stutter-free servo motors
More precise motion control
Ein Servo motor with low cogging torque enables more accurate and repeatable positioning, which is essential for smooth positioning . Example: A packaging machine applies labels with ±0.1 mm accuracy. Servo motors with minimized cogging torque ensure this precision at variable speeds and reduce the scrap rate by up to 5%.
- Enabling more accurate and repeatable positioning.
- Ensuring precision at variable speeds and reducing the scrap rate by up to 5%.
- Reduced wear and extended lifespan through quieter operation.
- Preserving motor and mechanics through lower vibrations.
- Potential extension of the lifespan of the drive unit by 10-15% due to reduced microvibrations.
- Improved performance in demanding areas such as robotics.
- Improvement of cycle times by up to 8% through stutter-free operation at slow speeds.
Reduced wear and longer lifespan
The quieter operation that a Servo motor with low cogging torque offers reduces wear. Lower vibrations conserve the motor and mechanics (gear boxes, bearings), which is particularly advantageous for applications focused on smooth positioning . Reduced microvibrations can extend the lifespan of the drive unit by 10-15%. Relevant for quality, e.g., with backlash-free planetary gear boxes..
Improved performance in demanding applications
The strengths of these motors are particularly evident in robotics: Servo motors with low cogging torque enable smooth, precise movements for complex assemblies (e.g., robot arm, 0.02 mm repeatability), which provides an extremely smooth positioning ensures. Jerk-free operation, especially at slow speeds, can improve cycle times by up to 8%. Optimized bevel gearboxes for robotics support this.Select: Find the right servomotor for your application
consideration of application requirements
The selection of the right motor, especially a servomotor with low cogging torque for smooth positioning, requires a thorough analysis of the specific requirements (torque, speed, positional accuracy). Considering the load cycle, not just peak values, avoids oversizing and can save costs by up to 20%.
The role of high-resolution feedback systems
High-resolution feedback systems are crucial to fully utilize the potential of Servo motors with low cogging torque . Encoders provide precise rotor position data, allowing controllers to effectively compensate for any residual cogging and ensure an extremely smooth positioning can ensure. Encoders over 20 bits/revolution can improve positioning accuracy by a factor of 2-4. Integrated into servomotors with encoders.
Environmental conditions and system integration
Factors such as temperature, vibration, dust, humidity, and special requirements (e.g., hygienic design) influence the selection of the servomotor with low cogging torque. Mechanical and electrical system integration with appropriate servo controllers is critical for performance and reliable smooth positioning; it can reduce commissioning time by up to 30%.Integrated gear motors simplify this process.Compare: Weigh servomotors with low cogging against alternatives
Comparison with standard servomotors
Standard servomotors are precise, yet a Servo motor with low cogging torque offers superior smoothness. This is particularly important for even movements at low speeds and thus for excellent smooth positioning e.g., during scans. Special motors can improve movement uniformity by 50% compared to standard servos.
- Superior smoothness of low-cogging servos compared to standard servos, especially at low speeds (up to 50% better movement uniformity).
- Unsuitability of stepper motors for very smooth movements due to discrete positioning and holding torque.
- Higher dynamics and 3-5 times higher speeds of low-cogging servos compared to stepper motors.
- Instant correction of positional deviations through closed-loop control in servomotors.
- The ability to reduce errors to arc seconds through high control quality of servos.
- Risk of lost steps in stepper motors in open-loop operation.
- Application-specific decision-making in motor selection.
Comparison with stepper motors
Stepper motors position discretely and have an inherent holding torque, making them often unsuitable for very smooth movements despite their high holding torque at standstill. In contrast, Servo motors with low cogging torque offer higher dynamics and can achieve 3-5 times higher speeds than stepper motors, making them ideal for demanding tasks in smooth positioning. applications.
Advantages of servomotors in terms of speed and control
The closed-loop control of servomotors, especially in models with low cogging torque, corrects positional deviations instantly and allows for higher speeds as well as accelerations. This is a clear advantage for precise and smooth positioning. The high control quality can reduce errors to arc seconds, while stepper motors may experience lost steps in open-loop operation.Servo gear motor solutions are designed for this purpose.
The selection of motors is application-specific and critical. A servomotor with low cogging torque for smooth positioning provides significant advantages in precision and smoothness. Careful selection according to the stated aspects leads to optimal drive solutions for your specific requirements.
