Perhaps the most obvious is to improve precision, which really is a function of manufacturing and assembly tolerances, gear tooth surface finish, and the guts 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 mistake of over-specifying the engine. Remember, the insight pinion on the planetary must be able manage the motor’s result torque. What’s more, if you’re utilizing a multi-stage gearhead, the output stage should be strong enough to soak up the developed torque. Certainly, using a better motor than required will require a bigger and more expensive gearhead.
Consider current limiting to safely impose limits on gearbox size. With servomotors, result torque is a linear function of current. So besides protecting the gearbox, current limiting also shields the electric motor and drive by clipping peak torque, which may be anywhere from 2.5 to 3.5 times continuous torque.
In each planetary stage, five gears are concurrently in mesh. Although it’s impossible to totally eliminate noise from such an assembly, there are several 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 costly than lighter duty types. However, for fast acceleration and deceleration, a servo-grade gearhead could be the only sensible choice. In this kind of applications, the gearhead may be viewed as a mechanical springtime. The torsional deflection resulting from the spring action adds to backlash, compounding the consequences of free shaft movement.
Servo-grade gearheads incorporate a number of construction features to reduce torsional stress and deflection. Among the more prevalent are large diameter output shafts and beefed up support for satellite-equipment shafts. Stiff or “rigid” gearheads tend to be the most costly of planetaries.
The kind of bearings supporting the output shaft depends upon the load. High radial or axial loads generally necessitate rolling component bearings. Small planetaries could get by with low-cost sleeve bearings or various other economical types with relatively low axial and radial load ability. For bigger and servo-grade gearheads, durable result shaft bearings are often required.
Like the majority of gears, planetaries make sound. And the quicker they operate, the louder they get.
You’ll find that there are lots of resources readily available for info pertaining to low backlash gearbox, however obviously they are of differing degrees of reliability.
