Many
are under the misconception that there are vast differences between servo
motors and stepper motors. Here, we attempt to dispel the notion and provide a
more realistic view.
1.
Torque. A stepper motor
has about the same torque as a comparably sized servo motor frame. A servo
motor offers an additional time-dependent peak toque rating, a more flexible
speed curve, and higher performance but a properly sized stepper motor could
help you realize a better cost savings over a servo. It is important to note
however, that stepper motors operate at full torque while the advantage of a
servo motor is the ability to control torque in an application.
2.
Applications. If an
application requires complete standstill stability, a stepper motor is the
better choice. Servo motors, however, pulsate back and forth on standstill.
Servo's are the better choice in vertical applications in which the motor must
hold a load still and for smooth operations while applications such as vision
system positioning are better suited for a stepper motor.
3.
Terminology. 'Servo' is
the term used of a motor applied on a closed-loop system. A stepper motor can
be optimized for the same application with identical functionality as a servo
but at a reduced cost and a slower speed.
4.
Micro-stepping.
Micro-stepping is the means of providing half-steps to a motor that offers
fewer steps than desired. Micro-stepping is achieved by dividing the current
between the two poles in the motor thereby increasing the resolution. However,
micro-stepping can have an adverse effect on a stepper motor because it can
reduce torque up to 30%.
5.
Acceleration. Stepper
motors are not as flexible with torque as are servo motors. Stepper motors
require much more power on acceleration that at any other time therefore torque
requirements must lie within the nominal curve for the stepper motor. Peak
torque for a servo motor must lie within peak torque curve and the Root Mean
Square torque of the overall cycle.
6.
Size. Manufacturers of
stepper motors and servo motors generally offer comparable frame sizes with the
only difference in size being the length. Length allows different torques and
inertia values to be obtained by the same size motor, offering greater
performance without increasing the size of the motor or its cost. The result is
a more cost effective solution that requires less installation space.
7.
Speed. Servo motors are
known for speed however, servo's are often used for applications in which the
motor provides more RPMs than necessary. In such cases, belt drives, for
instance, a stepper motor would fully suffice.
8.
Power. Whether it's a
stepper motor or a servo motor, the more current applied results in more
torque. The advantage of a stepper motor in this regard is the amount of torque
that can be generated at a safe voltage.
More about learn about Both motor check My video, stepper Motor Basic. And How do servo motors work.
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