Perhaps the most apparent is to increase precision, which really is a function of manufacturing and assembly tolerances, gear tooth surface finish, and the center distance of the tooth mesh. Sound can be suffering from gear and housing components as well as lubricants. In general, be prepared to pay out more for quieter, smoother gears.
Don’t make the error of over-specifying the motor. Remember, the insight pinion on the planetary should be able manage the motor’s output torque. Also, if you’re using a multi-stage gearhead, the output stage should be strong enough to absorb the developed torque. Certainly, using a more powerful motor than required will require a larger and more expensive gearhead.
Consider current limiting to safely impose limitations on gearbox size. With servomotors, result torque is a linear function of current. Therefore besides protecting the gearbox, current limiting also defends the motor and drive by clipping peak torque, which can be anywhere from 2.5 to 3.5 times continuous torque.

In each planetary stage, five gears are simultaneously in mesh. Although you can’t really totally get rid of noise from this assembly, there are many ways to reduce it.

As an ancillary benefit, the geometry of planetaries matches the shape of electric motors. Therefore the gearhead could be close in diameter to the servomotor, with the output shaft in-line.
Highly rigid (servo grade) gearheads are generally more expensive than lighter duty types. However, for speedy acceleration and deceleration, a servo-grade gearhead may be the only sensible choice. In this kind of applications, the gearhead may be viewed as a mechanical spring. The torsional deflection caused by the spring action adds to backlash, compounding the consequences of free shaft motion.
Servo-grade gearheads incorporate a number of construction features to minimize torsional stress and deflection. Among the more prevalent are large diameter result shafts and beefed up support for satellite-gear shafts. Stiff or “rigid” gearheads have a tendency to be the costliest of planetaries.
The kind of bearings supporting the output shaft depends on the load. High radial or axial loads usually necessitate rolling component bearings. Small planetaries could get by with low-price sleeve bearings or other economical types with fairly low axial and radial load capability. For bigger and servo-grade gearheads, durable result shaft bearings are usually required.
Like most gears, planetaries make sound. And the quicker they run, the louder they obtain.

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