Factors to Consider in Servo Motor Sizing
To select the right servo motor, it is essential to consider the mechanical and dynamic characteristics of the load and the operating environment. The main factors include:
Torque
Torque is one of the important factors for sizing a servo motor. It determines the motor's capacity to generate the necessary force to move a load. To correctly size the motor, it's essential to calculate the maximum torque required during the operating cycle, including starts, stops, and operations under load. A suitably sized motor means it operates efficiently, it is not overloaded, and premature failures are prevented. It's thus vital to select a servo motor whose torque is compatible with the application's demands, including a safety margin to manage unexpected load peaks.
Speed
Speed is another important factor when selecting a servo motor. It defines how fast the motor can operate, which in turn directly influences cycle time and machine productivity. When sizing a servo motor, the maximum speed required by the application should also be taken into account, including variations during different phases of the work cycle. With the correct speed specification, the motor will meet operational requirements without exceeding its limits, which could result in accelerated wear or failure.
Inertia
The inertia of the load affects the system's ability to accelerate and decelerate efficiently. The ratio between the inertia of the motor and that of the load should be optimized to ensure quick responses and precise control.
A significant difference between these inertias can lead to inadequate motion control, increasing the risk of vibrations and instability. It's therefore essential to calculate the system's total inertia and choose a motor with compatible inertia to guarantee optimized performance.
Voltage
Voltage is a crucial consideration when selecting servo motors and their servo drives. It determines the electrical compatibility between the motor and the power grid or power supply.
Selecting a servo motor with the appropriate voltage is fundamental to avoid electrical overloads and ensure efficient operation. It's important that the servo motor's voltage matches the control system and power source, thus maximizing energy efficiency and minimizing the risk of damaging the motor.
Current
Current plays a vital role in the operation of servo motors, as it has a direct impact on torque and power. When selecting a servo motor, assessing the maximum current required by the motor during operation is a must.
Choosing a servo drive that can provide the necessary current without exceeding limits is just as crucial in order to prevent the motor from overheating and provide safe and reliable operation. The appropriate current allows optimal motor performance and supplies the required torque for the application.
Temperature
Temperature management is an important mechanical and electrical consideration when selecting servo motors. Motors generate heat during operation, and the ability to dissipate this heat affects the motor's efficiency and lifespan.
Choosing a servo motor and servo drive with good thermal characteristics will allow for the temperature to be maintained within safe limits. This means that the operating environment, any available ventilation or cooling, and the thermal efficiency of the motor and driver need to be considered too so that overheating can be avoided, and stable performance is guaranteed.
Power
The power of the servo motor is determined by the combination of voltage and current and is an indicator of the motor's capacity to carry out work.
When selecting a servo motor, it's crucial to choose one with the appropriate power for the application; it will then be able to perform the required tasks without exceeding its capacity. Selecting a compatible servo drive capable of delivering the necessary power to the motor without inefficiencies is equally fundamental to optimize system performance as well as energy efficiency.
Servo Drive and Communication Network
Another aspect that determines the efficient performance of a servo motor is the servo drive and communication network. The driver should be capable of translating control commands into precise motor actions, while the communication network should be able to quickly and reliably transfer data between the motor, driver, and control system (PLC).
Compatibility between these components is crucial for designing a cohesive motion control system that can effectively respond to operational demands, thus providing precision, efficiency, and flexibility in industrial automation.
Best Practices for Sizing and Selecting Servo Motors
When sizing and selecting servo motors, it is advisable to follow a set of best practices to obtain the most effective and efficient choice for your specific application needs. Here are the recommended practices:
- Check Available Voltage:
Make sure that the servo motor is compatible with your installation's power supply voltage. - Define Motion Profile:
Analyze the speed requirements throughout the operation cycle, including acceleration and deceleration phases. - Calculate Required Torque:
Determine the torque needed based on mechanism inertia, friction, and external forces. - Evaluate Inertia Ratio:
Assess the ideal inertia ratio between the load and the motor rotor to improve control and system response. - Preliminary Servo Motor Selection:
After defining the key criteria, select a motor that meets the requirements for power supply voltage, nominal speed, continuous and peak torque, and inertia. - Determine Using a Gearbox:
If the application requires speed reduction, increasing torque and improving inertia ratio, consider adding gears (reducers) to the system. - Final Servo Motor Selection:
Refine your choice by adjusting the reduction ratio, required torque, and inertia ratio to find the most suitable motor. - Complete Sizing with a Servo Drive:
Choose a servo drive with the correct input voltage and sufficient output current, and a suitable control interface.
Use our configurator Electric Motion Sizing and size your electric or electromechanical drive system quickly, easily and precisely.
Summary
Choosing the correct servo motor starts with a thorough understanding of your application’s load, torque, speed, and environmental requirements. By carefully considering these factors and adhering to best practices in sizing and selection, you can secure a servo motor that delivers accurate, efficient, and reliable motion control tailored to your system’s needs.
