Indexer Motion Improves

A new hardware/software bundle for implementing programmable, direct drive operation for mechanical indexers simplifies system set-up and provides a fully tested software solution. The solution targets both new designs and retrofits, such as existing Camco-Ferguson mechanical indexers, which would benefit from higher performance motion control.

“If an engineer wants to replace a mechanical indexer with direct drive operation, they no longer need to size the motor, pick cables, specify a separate controller and do the work to program it,” says Jeff Arnold, technology specialist, Direct Drive for Danaher Motion.

The product offering consists of a motor, drive-controller electronics, cables and an HMI with a complete set of software for implementing programmable indexers. Users mount the motor, bolt the load to it, hook up the cables and HMI, and it is very simple to set-up the index moves required for the application.

By eliminating the gear train and components in a mechanical system while adding programmable features, the product provides flexibility and enables users to achieve software selectable motion sequences that wouldn’t be possible with a mechanical indexer.An example is the ability to easily change index angle, speed and dwell.Another key advantage is the ability to immediately stop motion if there is a process error.

Arnold says precision technology allows for superior repeatability to ±1.2 arc-sec with no backlash and system accuracies to ±26 arc-sec. In comparison, he says mechanical indexers typically provide best-case repeatability to ± 33 arc-sec and accuracy to ±66 arc-sec.

This indexer product set can rotate clockwise or counter clockwise to achieve the shortest time and provide maximum flexibility. Index times are programmable and no homing is ever required because absolute position feedback maintains position even under power cycling.

Using the direct drive approach, either for new designs or retrofits, there are a number of system benefits. Arnold says accuracy and repeatability of the system increases and, unlike mechanical indexers, motion performance will not degrade over time. The new systems also provide a 20dB reduction in system noise compared with mechanical indexers.

“The direct drive implementation reduces the part count for the indexing solution and dramatically reduces noise,” says Arnold.“If a mechanical indexer is running, the two people standing near it either need to yell to be heard or walk away to carry on a conversation.With direct drive when you turn your back on the system, you almost can’t tell that it is running.”

A complete set of motors that offer continuous torques from 8 to 250 lb-ft provide solutions for a wide variety of application requirements. And unlike mechanical indexers that require regular maintenance checks and service, the rotary indexer product set is lubricated for life and requires no maintenance over the entire life of the machine. Combined with rapid system start-up, Arnold says the system offers low total cost of ownership and high performance rotary indexing.