Perhaps the most apparent is to increase precision, which really is a function of manufacturing and assembly tolerances, gear tooth surface finish, and the center distance of the tooth mesh. Sound is also suffering from gear and housing materials along with lubricants. In general, be prepared to pay out more for quieter, smoother gears.
Don’t make the error of over-specifying the motor. Remember, the insight pinion on the low backlash planetary gearbox planetary must be able handle the motor’s result torque. What’s more, if you’re using a multi-stage gearhead, the result stage must be strong enough to soak up the developed torque. Obviously, using a better motor than necessary will require a larger and more costly gearhead.
Consider current limiting to safely impose limitations on gearbox size. With servomotors, output torque is usually a linear function of current. So besides protecting the gearbox, current limiting also defends the electric 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 concurrently 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 fits the shape of electric motors. Hence 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 may be the only wise 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 motion.
Servo-grade gearheads incorporate a number of construction features to minimize 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 have a tendency to be the most costly of planetaries.
The type of bearings supporting the output shaft depends upon the load. High radial or axial loads usually necessitate rolling element bearings. Small planetaries could get by 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 result shaft bearings are often 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 to about 50:1 or more, planetary gearheads extend from 3:1 (solitary stage) to 175:1 or even more, depending on the number of stages.