The rotary indexing table has been used in automated processes for many decades. Rotary indexers are utilized in automation to provide high accuracy and repeatable positioning to present a part at various stations to perform a specific process. Up until a decade ago it was most common to implement a fixed cam rotary indexer. A fixed cam rotary indexing table has an internal cam and cam follower mechanism that is manufactured to a customer’s specification of how many stops they require to have for their application. When talking about number of stops on a fixed rotary indexing table application, we are referring to how many times the output dial will go into a mechanical dwell in a 360-degree rotation. For example, a 4-stop rotary indexer will go into the mechanical dwell every 90 degrees; a 3-stop rotary indexer will go into the mechanical dwell every 120 degrees.
Over the last several years the reliable mechanical solution that a fixed cam indexer provides has been forgotten by some engineers, or younger ones don’t even know it exists.
In most rotary index table applications, a fixed degree of motion from station to station never needs to be changed; however, some will believe they need flexibility. With a fixed cam indexer the implementation time is reduced and the reliability over time cannot be matched with a programmable solution.
Fixed cam indexers are operated by using AC motors, which can be operated with a simple VFD or contactor/motor starters. You do not need servo motors or drives. Positioning is achieved by the mechanical dwell of the internal cam. With a fixed cam indexer there is never a need to “REHOME” or worry about position drifting over time due to encoder count rollover.
Programmable indexers do have a purpose and it is important to understand when a programmable indexer should be used. Such as:
- When you have a single dial but want to have batch runs of 2 or more parts. A programmable indexer gives you the ability to program multiple movement profiles to provide the ability to run multiple parts in separate batches without having to go through a mechanical dwell.
- When there is a need to rotate a different degree intermittently to have a part inspected or rejected – for example: A customer has a 4-station index table application and the third station is an inspection station; some customers like the ability to be able to index 45 degrees if a part should have to be rejected. This would not happen on every cycle but they need the ability to reject a part prior to being unloaded if it is a bad part.
- When the customer wants an additional axis to their robot. Our RTF and TMF all have the ability to be an additional axis to most major robot brands. An aux axis motor enables the indexer to become an extension to the robot and be able to communicate with it.
You also need to consider when to not overlook the reliability and reduced commissioning time that a fixed indexer can provide for both the system integrator and the end customer.
Motion index Drives fixed RTX Rotary Indexing Tables are suitable for any application that is going to have a set number of stations or positions and the process of the cell is always going to index.
The RTX indexing table is often used in the assembly technology, the testing technology, the welding technology, the printing, the pressing, the automotive industry, the microelectronics, the food industry, the medical and the cosmetic industry.
FEATURES AND USER BENEFITS
- Reliable, robust drum cam roundtable for all applications
- Construction diameter 100mm – 285mm
- Fixed divisions 2 – 96 or flexible through NC technology
- Switching times of 0.16s – 5s
- Gentle starting and stopping across the switching cam
- Large, vertically hollow shaft
- Ideal for high loads
- Standard accuracy 15″ – 35″
- Four-point mounting at the outer diameter of the output flange
- Maintenance-free through oil bath lubrication
- Stop operation, continuous operation or reversing design possible
- All installation positions possible