Perhaps the most apparent is to increase precision, which 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 and also lubricants. In general, be low backlash gearbox prepared to spend more for quieter, smoother gears.
Don’t make the error of over-specifying the engine. Remember, the insight pinion on the planetary should be able handle the motor’s result torque. What’s more, if you’re using a multi-stage gearhead, the output stage must be strong enough to absorb the developed torque. Certainly, using a more powerful motor than necessary will require a larger and more expensive gearhead.
Consider current limiting to safely impose limits on gearbox size. With servomotors, output torque is usually a linear function of current. Therefore besides protecting the gearbox, current limiting also shields the 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 it’s impossible to totally eliminate noise from such an assembly, there are many methods to reduce it.
As an ancillary benefit, the geometry of planetaries fits the form of electric motors. Therefore 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 quick acceleration and deceleration, a servo-grade gearhead could be the only sensible choice. In such applications, the gearhead may be viewed as a mechanical springtime. The torsional deflection caused by the spring action adds to backlash, compounding the consequences of free shaft motion.
Servo-grade gearheads incorporate a number of 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 kind of bearings supporting the output shaft depends on the strain. High radial or axial loads generally necessitate rolling component bearings. Small planetaries could manage with low-cost sleeve bearings or additional economical types with relatively low axial and radial load capacity. For bigger and servo-grade gearheads, heavy duty output shaft bearings are usually required.
Like the majority of gears, planetaries make sound. And the quicker they operate, the louder they get.
Low-backlash planetary gears are also obtainable in lower ratios. While some types of gears are generally limited to about 50:1 and up, planetary gearheads expand from 3:1 (one stage) to 175:1 or even more, depending on the amount of stages.