Perhaps the most significant advancement in gearbox design is the transition from a parallel shaft profile to a true planetary design. Where traditional gearboxes meshed two gears together on parallel shafts, most high-performance gearboxes today use a planetary arrangement in which the gears mesh at three points of contact. This arrangement provides load sharing between the gears, which increases torque performance and overall life.
Further improvements on the planetary design can be achieved by cutting the gears on a helix angle. These helical planetary gears increase the number of teeth in mesh at any given time, which produces a stronger, more accurate and quieter-running gearhead.
Heat treat processes
The heat treat processes used on the internal gearing directly impact the overall performance on any gearhead. Some manufacturers use lower-cost, chemical heat treat processes that do not hold up under the extreme torque or high duty cycle applications. For higher performance and longer life, many manufacturers use a case-hardening heat treat process that increases the hardness layer by more than 30 times compared to alternatives. Even the best and most robust designs will not hold up for an extended period of time if the proper heat treat methods are not used.
Gears with a higher level of hardness will have less wear and last longer. The Thomson ValueTRUE True Planetary Gearheads increase torque capacity and offer higher precision.
Quick, Error-Free Installation
In the past, mounting of traditional gearheads was a painstaking process. There were several steps that introduced possibilities for human error such as the mounting of the gearhead pinion gear, or sun gear, on the motor shaft. This usually required precise, time-consuming measurements that increased the chance of failure if not done properly. Today, however, most gearhead manufacturers have modified their designs to make mounting procedures faster, easier and free of potential errors. Mounting can now be done in a few easy steps in under five minutes.
Balancing application tradeoffs
While servo motors and gearboxes can be found together in almost every market, gearbox usage varies based on design engineers' needs. Gearboxes are designed for specific applications (or at least for specific application requirements) and provide flexibility when sizing a servo motor to achieve desired operating loads and speeds. However, choosing a gearbox requires some tradeoffs among cost, precision, performance, durability and environmental protection.
Users implementing gearboxes in operations such as snack bar packaging, for example, are more concerned with speed than precision. They are less concerned about backlash or torque than about maximizing throughput on the packaging line at the lowest cost and longest life, considering the durability of both the gearbox and the servo motor. Customers in wet process food applications, such as cutting bacon slices or producing frozen French fries, also might opt for speed over precision but would value sanitary, stainless steel material that is sealed to meet ingress protection (IP) standards, including protection against high-pressure equipment wash-downs.
Users of gearboxes on robots, on the other hand, would be more concerned about envelope size. They might, for example, be implemented on an arm that is already designed to minimize overhang stress and may not tolerate the further extension an added gearbox might introduce. Precision is also critical here, making the challenge to provide the maximum precision and stiffness in the smallest envelope. Robotics users are more likely to trade off cost for performance and footprint.
