Configuring a Motion Control System

Mechanical components in this section include linear actuators, gearheads and mechanical connectors/couplings. In most systems, they provide critical links to the motor and/or load. As a result, these components must keep up to the performance, size and cost trends driving other portions of the motion control system. In an increasing number of instances, added features provide critical differentiation. However, in some cases, there are alternatives to traditional solutions or requirements that go beyond the norm.

Direct Drive Rotary Stages

While gearheads provide torque and speed transitions for many applications, in some cases, an alternative is required. Applications such as inertial navigation device testing, photonic component alignment, high-accuracy laser machining and precision wafer inspection can benefit from a direct drive rotary stage. Unlike worm-drive stages, a direct-drive stage has no gear wear or gear vibration. In addition, a direct drive operates faster than a worm drive to reduce test time and increase manufacturing throughput.

Case in point, Aerotech ALAR Series direct-drive, large-aperture rotary stages operate from 45 to 300 rpm continuous rotation in contrast to conventional worm-drive rotary stages with similar apertures and payload capacity that operate to 15 rpm or less. Offered in aperture sizes of 100, 150, 200, 250 and 325 mm, the stages have either continuous or limited travel. Eliminating gear trains and mechanical couplings avoids position errors caused by hysteresis, windup and backlash, resulting in an accuracy of ±3.9 arc-sec and bi-directional repeatability of ±0.5 arc-sec.

While a limited number of applications need the performance from this type of direct drive instead of a conventional geared solution, harsh operating conditions provide a more common application requirement for mechanical components.

That’s Harsh

Adding a washdown specification to a linear actuator revises the design requirements, yet many applications in packaging and food processing require this capability. A combination of alpha and WITTENSTEIN technologies in the Stainless SG inline planetary gear and the ternary intelligent linear actuator address this requirement. The SG’s design has no crevices for retaining fluids or promoting bacteria.