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 in addition to lubricants. In general, expect to pay out more for quieter, smoother gears.
Don’t make the error of over-specifying the engine. Remember, the input pinion on the planetary should be able handle the motor’s output torque. Also, if you’re using a multi-stage gearhead, the result stage must be strong enough to absorb the developed torque. Certainly, using a better motor than required will require a bigger and more expensive gearhead.
Consider low backlash gearbox current limiting to safely impose limitations on gearbox size. With servomotors, output torque can be a linear function of current. So besides protecting the gearbox, current limiting also protects the engine 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 at the same time 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. Thus the gearhead can 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 viewed as a mechanical springtime. The torsional deflection caused by the spring action adds to backlash, compounding the effects 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 tend to be the most costly of planetaries.
The type of bearings supporting the output shaft depends upon the strain. High radial or axial loads usually necessitate rolling component bearings. Small planetaries could manage with low-cost sleeve bearings or additional economical types with fairly low axial and radial load ability. For larger and servo-grade gearheads, heavy duty result shaft bearings are often required.
Like the majority of gears, planetaries make sound. And the quicker they operate, the louder they obtain.
Low-backlash planetary gears are also available in lower ratios. While some types of gears are generally limited to about 50:1 and up, planetary gearheads prolong from 3:1 (single stage) to 175:1 or more, depending on the number of stages.