To choose the right permanent magnet (PM) stepper motor, consider the following factors:
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Torque Requirements: Determine the torque needed to drive the load, including both holding torque (to keep the motor in position when not moving) and running torque (required during operation). If the torque is below 0.8Nm, choose a motor with a NEMA size of 8-17. For torque around 1-3Nm, a NEMA 23 motor may be suitable, while NEMA 34 or 42 motors are appropriate for torque greater than 3Nm. Select a motor that provides enough power without issues and achieves higher speeds, adding a safety factor for extremely high loads.
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Speed and No-Load Starting Frequency: Consider the required speed, as the motor’s output torque is inversely proportional to its speed. Prioritize applications needing frequent starts and stops around 1000 rpm or higher with “accelerated start”.
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Step Angle and Resolution: Evaluate the required positioning accuracy. Applications needing fine positional accuracy benefit from motors with smaller step angles.
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Environmental Conditions: Select a motor compatible with the operating environment’s temperature, humidity, and exposure to dust or chemicals. Motors designed for harsh environments have enhanced sealing and cooling mechanisms.
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Size and Mounting: Consider the installation space and mechanical constraints when selecting a motor size. Smaller motors fit into compact spaces but may offer lower torque, while larger motors provide higher power output but need more space.
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Driving Method: The performance of the stepper motor is affected by different driving modes. Driving methods normally include constant voltage and constant current driving, unipolar and bipolar driving.
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Cost: PM stepper motors are more cost-effective and best for budget-sensitive projects, in which simplicity is key.
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Application Requirements: Define the precise needs of your application. Determine whether you need high torque for heavy loads or high speed for rapid movements.