Indexers - Fixed Vs. Flexible Automation

Many of the world’s most significant and complex manufacturing operations – in industries ranging from aerospace to automotive, consumer goods to packaging, and nuclear medicine to life sciences – depend on automation systems to operate consistently, efficiently and safely. For many years, the dominant technology in this realm has been what is called a “fixed” system that relies on the operation of a Fixed-Stop Index Cam. This type of cam is a mechanical automation component that is machined for use on an indexer. The function of the Fixed-Stop Index Cam must be precise in two distinct operating periods: the index period, which dictates the number of degrees the cam needs to move the indexer into position, and the dwell period, which determines the length of time the cam stays still during the indexing process.

In more recent times, however, a new technology based on the operation of a Constant-Lead Cam has grown in popularity. As opposed to the Fixed-Stop Index Cam, the Constant-Lead Cam does not operate with rigid, unchanging dwell periods, which gives this style of indexing its “flexible” name. The movements of the Constant-Lead Cam are determined electronically via a programmable device, typically a servomotor. While Constant-Lead Cams do have a fixed indexing period, they have no true dwell period since the servomotor is designed to continually use infinitesimal movements to seek the best position, even when the cam has ostensibly completed its movement.



Both Fixed and Flexible Automation have their pros and cons, meaning operators should consider all variables when determining the best system for their particular operation.

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  • Because they are mechanical in nature, Fixed-Stop Cam startup requires no complicated programming or system debugging

  • When the cam stops, there is no chance any ancillary movement will occur

  • Fixed cams are very robust and can handle higher load capacities

  • Maintenance is simpler, with only an oil change and regreasing of parts required after a certain period of operation

  • Overall system cost is less expensive.
  • The fixed movements of the cams decrease system flexibility

  • Any change to the indexer’s operational parameters require major modifications to the cams

  • Fixed automation systems cannot provide process feedback to the operator
  • The servomotor can be reprogrammed to quickly adjust to changing operational parameters

  • Servomotor operation can be monitored to provide reports regarding power demand, uptime/downtime, displacement rate, velocity and acceleration/deceleration time

  • The system’s programmable logic controller (PLC) can sync with actions at previous or succeeding work stations.
  • The monitoring and feedback capabilities of flexible systems require additional hardware, which results in higher overall system cost

  • The technical skill needed to set up and operate a flexible system is greater

  • The constant searching, seeking and correcting of the servomotor during the dwell period can compromise precision


Contact DESTACO’s Camco Engineers, email, or call 888-DESTACO (337-8226) for questions on your specific application.