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 can be suffering from gear and housing materials as well as lubricants. In general, expect to pay out 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 deal with the motor’s output torque. What’s more, if you’re using a multi-stage gearhead, the result stage should be strong enough to soak up the developed torque. Certainly, using a better motor than required will require a larger and more expensive gearhead.
Consider current limiting to safely impose limits on gearbox size. With servomotors, result torque is definitely a linear function of current. Therefore besides safeguarding the gearbox, current limiting also defends the electric 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 simultaneously in mesh. Although you can’t really totally get rid of noise from such an assembly, there are many methods to reduce it.
As an ancillary benefit, the geometry of planetaries matches the form 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 usually more expensive than lighter duty types. However, for quick acceleration and deceleration, a servo-grade gearhead may be the only wise choice. In such applications, the gearhead could be viewed as a mechanical springtime. The low backlash gearbox torsional deflection caused by the spring action increases 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 result 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 upon the strain. High radial or axial loads usually necessitate rolling element bearings. Small planetaries could manage with low-cost sleeve bearings or additional economical types with relatively low axial and radial load ability. For larger and servo-grade gearheads, heavy duty result shaft bearings are often required.
Like most gears, planetaries make noise. And the quicker they run, the louder they obtain.
Low-backlash planetary gears are also obtainable in lower ratios. Although some types of gears are usually limited by about 50:1 and up, planetary gearheads expand from 3:1 (single stage) to 175:1 or more, depending on the amount of stages.