Benefits of Auxiliary Axis Integration

Companies are increasingly seeking cost-effective solutions for integrating robots with rotary indexers across a variety of applications, such as painting, welding, assembly, material handling, and more. Rotary indexers provide manufacturers with fast, precise, and highly repeatable positioning for their robots. These systems can also be customized with additional components to support various assembly and inspection processes, seamlessly integrating with existing production lines.

Custom rotary index tables can be tailored to match the specific robots and control systems in use, ensuring compatibility and maximizing efficiency. By eliminating the need for machine switchovers, rotary index drives help reduce costs. This eliminates the need to relocate or reprogram the robot, as the entire system functions as a single unit—controlled by a simple open-loop VFD controller and an explosion-proof AC motor. This streamlined approach helps manufacturers maintain productivity while minimizing complexity and downtime.

Motion Index Drives manufactures an extensive line of rotary index tables that can be adapted to accommodate robot auxiliary axis motors ultimately providing an additional axis to the robot. The auxiliary axis rotary index tables that Motion Index Drives manufactures are extremely accurate and are a true zero backlash mechanism. The zero backlash is achieved from the cam technology that creates the transmission of the system. There are multiple cam followers arrayed toward the outer diameter of the rotating dial giving the system maximum strength for its overall size.

How to Size your Application to Accommodate and Auxiliary Axis

As with all rotary index table applications, the key factor in proper sizing is the mass moment of inertia. This determines the speed at which the load can rotate over a specific angle and, in some cases, how quickly it can be stopped. The mass moment of inertia also helps ensure that the inertia mismatch stays within an acceptable range, allowing for optimal load control. Due to the exceptional rigidity of Motion Index Drives’ auxiliary axis indexers, a mismatch of up to 10:1 or more can still result in smooth, vibration-free movement without overloading the servo motor.

It is very important to know that when calculating the size of the indexer that will be required for an auxiliary axis application, the limitation for most robot manufacturers is the movement profile that can be used. In most cases when using an auxiliary axis motor the acceleration time has to match the deceleration time. It takes more torque to bring a load up to speed compared to bringing it to a stop, so when using an auxiliary axis motor that constraint alone can sometimes be the cause to increase the size of the indexer that will be best suited for that particular application. If movement profiles could be adjusted in aux axis software similar to servo motor applications, the acceleration can be prolonged and the deceleration can be shortened. In this situation the indexer can be optimized much better.

Facts to Know When Considering an Auxiliary Axis Motor for your Rotary or Linear Axis Application

Most robot manufacturers provide auxiliary axis motors for their robots. A Motion Index Drives engineer will assess the maximum torque required for the application and recommend the most suitable auxiliary axis motor model. The size of the indexer can be influenced by the need for quick stops during events like light screen incursions. For example, a stop time of 100 ms can generate much higher forces on internal components compared to a 500 ms stop time. Many robot manufacturers offer specialized software for emergency stop scenarios, allowing programmers to adjust deceleration rates and reduce the forces encountered during such events. It is highly recommended to use this software to optimize the size of the rotary index table for each specific application.

• You will have to purchase the auxiliary axis motor or motors when you purchase your robot from the manufacturer or by providing a serial number of an existing robot. Motion Index Drives will recommend the size and required features that will work with the rotary indexer or linear indexing devices based on all the loading and application information that was provided.
• Know that the size of indexer may have to increase in size overusing a traditional servo motor or AC motor with encoder due to the limited movement profile capabilities of the robot software. Most robot software limits the movement profile to a trapezoidal move or triangular motion profile. Both require the acceleration and deceleration to be the same.
• Avoid instantly applying brake on motor for all light screen violation and emergency stop conditions. A programmed deceleration for these occurrences must be implemented. There is additional software that is needed to be able program and to have an independent deceleration profile when these occurrences arise.
• If you plan on operating your auxiliary axis indexer in one direction, you have software that can handle encoder count rollovers.
• Make sure you are inputting the correct exact ratio into the drive. This can be done on some controllers by putting in the numerator/denominator or the exact calculated ratio. A common mistake is programmers looking at only the gear reducer provided on the indexer without adding the additional reduction in the indexer itself.
• It is highly recommended to have a Motion Index Drives technician validate that an auxiliary axis system has been properly programmed to avoid any premature failures. This can be done on site or by video sharing applications. This is the #1 cause of any rotary or linear indexing device.
• If you have provided correct loading, implement the recommended movement profiles, avoid instantly applying the brake during light screen violations, your precision indexer should run flawless for many years.