Perhaps the most apparent is to improve precision, which really is a function of manufacturing and assembly tolerances, gear tooth surface finish, and the center distance of the tooth mesh. Sound is also suffering from gear and housing materials in addition to lubricants. In general, expect to pay out more for quieter, smoother gears.
Don’t make the error of over-specifying the motor. Remember, the input pinion on the planetary must be able deal with the motor’s result torque. Also, if you’re utilizing a multi-stage gearhead, the result 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 can be a linear function of current. So besides safeguarding the gearbox, current limiting also protects the electric motor and drive by clipping peak torque, which may be from 2.5 to 3.5 times continuous torque.

In each planetary stage, five gears are concurrently in mesh. Although you can’t really totally eliminate noise from this assembly, there are several methods to reduce it.

As an ancillary benefit, the geometry of planetaries matches the form of electric motors. Thus the gearhead can be close in diameter to the servomotor, with the output shaft in-line.
Highly rigid (servo grade) gearheads are usually more expensive than lighter duty types. However, for speedy acceleration and deceleration, a servo-grade gearhead may be the only wise choice. In this kind of applications, the gearhead could be seen as a mechanical spring. The torsional deflection caused by the spring action increases 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 type of bearings supporting the output shaft depends upon the strain. High radial or axial loads usually necessitate rolling element bearings. Small planetaries can often manage with low-cost sleeve bearings or additional economical types with relatively low axial and radial load capacity. For larger and servo-grade gearheads, heavy duty result shaft bearings are usually required.
Like most gears, planetaries make noise. And the quicker they run, the louder they obtain.

low backlash gearbox is a fad that is slowly increasing.