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 affected by gear and housing materials in low backlash planetary gearbox addition to lubricants. In general, be prepared to pay more for quieter, smoother gears.
Don’t make the error of over-specifying the motor. Remember, the insight pinion on the planetary must be able manage the motor’s result torque. Also, if you’re using a multi-stage gearhead, the output stage should be strong enough to soak up the developed torque. Obviously, using a better motor than required will require a larger and more costly gearhead.
Consider current limiting to safely impose limits on gearbox size. With servomotors, result torque is definitely a linear function of current. So besides protecting the gearbox, current limiting also protects 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 concurrently in mesh. Although it’s impossible to totally remove noise from such an assembly, there are several ways to reduce it.
As an ancillary benefit, the geometry of planetaries fits the form 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 speedy acceleration and deceleration, a servo-grade gearhead may be the only sensible choice. In this kind of applications, the gearhead may be viewed as a mechanical spring. The torsional deflection resulting from the spring action adds to backlash, compounding the effects of free shaft motion.
Servo-grade gearheads incorporate several construction features to reduce torsional stress and deflection. Among the more prevalent are large diameter output shafts and beefed up support for satellite-gear shafts. Stiff or “rigid” gearheads have a tendency 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 element bearings. Small planetaries could manage with low-cost sleeve bearings or additional economical types with fairly low axial and radial load ability. For bigger and servo-grade gearheads, heavy duty result shaft bearings are usually required.
Like the majority of gears, planetaries make noise. And the faster they run, the louder they obtain.
Low-backlash planetary gears are also available in lower ratios. Although some types of gears are generally limited by about 50:1 or more, planetary gearheads expand from 3:1 (solitary stage) to 175:1 or more, depending on the amount of stages.