Perhaps the most apparent 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 is also suffering from gear and housing materials in addition to lubricants. In general, expect to spend more for quieter, smoother gears.
Don’t make the mistake of over-specifying the electric motor. Remember, the input pinion on the planetary should be able manage the motor’s result torque. Also, if you’re utilizing a multi-stage gearhead, the output stage must be strong enough to soak up the developed torque. Certainly, using a better motor than required will require a larger and more costly gearhead.
Consider current limiting to safely impose limitations on gearbox size. With servomotors, result torque is definitely a linear function of current. Therefore besides protecting the gearbox, current limiting also protects the 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 at the same time in mesh. Although you can’t really totally remove noise from such an assembly, there are many ways to reduce it.
As an ancillary benefit, the geometry of planetaries matches the shape 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 generally more expensive 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 could be viewed as a mechanical springtime. The torsional deflection caused by the spring action adds to backlash, compounding the consequences of free shaft movement.
Servo-grade gearheads incorporate many construction features to reduce torsional stress and deflection. Among the more common are large diameter result shafts and beefed up support for satellite-gear shafts. Stiff or “rigid” gearheads tend to be the most costly of planetaries.
The type of bearings supporting the output shaft depends upon the load. High radial or axial loads generally necessitate rolling component bearings. Small planetaries can often manage with low-cost sleeve bearings or other economical types with fairly low axial and radial load ability. For bigger and servo-grade gearheads, heavy duty output shaft bearings are often required.
Like the majority of gears, planetaries make noise. And the quicker they operate, the louder they obtain.
The possibilities are countless with low backlash gearbox!