Rotary actuators play a significant role in many industrial automation processes. Machinery such as indexing tables, rotary tables, and part pick and place systems require powerful, precise, and long-lasting methods of rotationally moving objects. Traditionally, this has been performed with devices such as pneumatic indexing systems and cam indexers driven by electric motors. However, in recent years, direct drive actuators such as the CKD’s Absodex line have proved to be a much better alternative to other indexing methods, providing a number of benefits, including increased repeatability, higher torque outputs, and reduced maintenance demands.
What is a Direct Drive Actuator?
Much like conventional electric motors, direct drive actuators convert mechanical energy into rotational energy. The difference with direct drive units is that the rotor and stator are part of the body of the motor itself. Instead of relying on an output shaft and connecting to a gearbox, belt drive, or other mechanical transmission means, direct drive actuators, as the name suggests, directly drive the rotational mass. Rotation is controlled by controlling the magnetic field around the body of the actuator which controls the magnets in the rotor. An encoder reads the position of the actuator and provides feedback to the controller. When the actuator needs to move, electrical current is used to change the magnetic field in the stator coils, causing the rotor to turn. Bearings are then used to support the load depending on the application with different styles being available for higher loads, increased accuracy, or reduced size. Want more detailed manufacturer information?
Cutaways of the inside of an Absodex direct drive actuator. The design allows the units to be extremely compact while limiting mechanical components to a single bearing.
Benefits Over Other Methods
Direct drive actuators have been around for a while but have been becoming an increasingly popular option for rotational motion applications due to some of the following benefits:
Precision and Accuracy
Direct drive actuators provide extreme accuracy and repeatability of the units. Due to the lack of any external mechanical transmission and the magnetically driven system, direct drive actuators have zero backlash – or free play between mechanical components that is common with other systems. This results in consistent, repeatable movements; a must for any part placement or rotary indexing applications where parts need to be consistently moved with little to no variation. Direct drive actuators also use extremely accurate encoders, meaning the pulses per revolution; or the number of positions that the actuator can move in a complete rotation is extremely high. CKD’s Absodex direct drive units start 600,000 pulses per revolution with accuracies of 30 arcseconds (0.0083 degrees) up to 8,000,000 pulses per revolution with an accuracy of 15 arcseconds (0.0042 degrees) with options for even higher step counts for specialized applications.
Reduced Maintenance and Downtime
Another benefit of direct drive actuators is their reduced maintenance requirements and associated downtime when compared to more traditional systems. In these advanced actuators, the only mechanical moving part is the bearing, which minimizes the complexity of the design and greatly enhances reliability. Unlike conventional systems that often rely on drive belts, clutches, and couplings that may require periodic replacement, direct drive actuators eliminate this concern altogether. With significantly fewer mechanical components that can wear out over time, maintenance schedules become much simpler and more straightforward. This streamlined approach allows for longer operational periods, ultimately translating to improved efficiency and productivity in various applications.
While traditional mechanical indexing units require many different components to function properly, direct drive actuators are entirely self-contained, using only a single bearing.
Compact Design and Integration Flexibility
Space is always at a premium when designing new equipment, and indexing tables are no exception to this challenge. Traditionally, mechanically driven systems tend to occupy a substantial footprint within a machine, primarily because they require a mechanical coupling between the indexing table and the motor. This often results in designs that are both tall and bulky. In contrast, direct drive actuators offer a compelling advantage with their low form factor, taking up significantly less space than traditional motor drives. Furthermore, direct drive actuators can be easily configured with a through hole in the center, something that is often much more complex to achieve with conventional indexing drives. This design feature not only maximizes space efficiency but also facilitates seamless integration into existing machinery, as these compact units require considerably less room. Overall, the adoption of direct drive actuators allows for more innovative designs while addressing the crucial need for space optimization in equipment development.
Direct drive actuators remove the need for traditional mechanical transmission components, making them extremely compact.
Programmability and Customization
In today’s fast-moving industrial world, manufacturing processes must be designed around being flexible in order to stay up to date with current demand. To this end, direct drive actuators are a fantastic means of ensuring your indexing table project stays future proof. Traditional cam indexing systems only have a set number of positions, requiring the entire unit be changed if more indexing stations are required down the road. However with a direct drive actuator, indexing stations can be reconfigured in minutes. This allows for greatly increased flexibility as processes change over time. Direct drive units can also be configured with advanced motion profiles, allowing for precise control over speed and torque curves as well as nonuniform rotation profiles and even reverse movements, allowing for highly advanced movement profiles that would otherwise be impossible with traditional indexing drives.
Besides having nearly limitless configurations of indexing stations, the Absodex direct drive has the added benefit of configurable movement profiles, torque curves, and reversible rotation.
Closing Thoughts
Direct drive actuators, though established for some time, have recently gained significant traction as a viable option for rotary applications like indexing tables. Among these, the Absodex series by CKD stands out as an exceptional product, offering high accuracy, customization, and a simplified approach to rotational drives. As demand for precision and efficiency continues to grow, the Absodex series exemplifies the evolution and effectiveness of direct drive technology.
Interested in seeing how your next rotary application can benefit from an Absodex direct drive? Contact our technical experts today!