Perhaps the most obvious is to increase precision, which is a function of manufacturing and assembly tolerances, gear tooth surface finish, and the center distance of the tooth mesh. Sound is also affected by gear and housing components and also lubricants. In general, be prepared to pay out more for quieter, smoother gears.
Don’t make the error of over-specifying the electric motor. Remember, the input pinion on the planetary must be able deal with the motor’s result torque. Also, if you’re using a multi-stage gearhead, the result stage should be strong enough to soak up the developed torque. Obviously, using a better motor than required will require a larger and more expensive gearhead.
Consider current limiting to safely impose limitations on gearbox size. With servomotors, output torque is definitely a linear function of current. So besides safeguarding the gearbox, current limiting also protects the motor and drive 
by clipping peak torque, which can 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 many methods to reduce it.
As an ancillary benefit, the geometry of planetaries matches the form of electric motors. Thus the gearhead could be close in diameter to the servomotor, with the result shaft in-line.
Highly rigid (servo grade) gearheads are generally more expensive than lighter duty types. However, for fast acceleration and deceleration, a servo-grade gearhead may be the only sensible choice. In such applications, the gearhead could be seen as a mechanical spring. The torsional deflection caused by the spring action adds to backlash, compounding the consequences of free shaft movement.
Servo-grade gearheads incorporate several construction features to minimize torsional stress and deflection. Among the more common are large diameter output shafts and beefed up support for satellite-gear shafts. Stiff or “rigid” gearheads tend 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 can often manage with low-price sleeve bearings or additional economical types with relatively low axial and radial load capability. For bigger and servo-grade gearheads, durable result shaft bearings are usually required.
Like most gears, planetaries make noise. And the faster they run, the louder they obtain.
Hope you appreciated this article, to discover much more on low backlash gearbox see our site.