What is Indexing?

Indexing is the repetitive movement of a mechanical element, from an initial position (starting from a rest position also known as dwell) to a new position. In other words, it can also be defined as the process of starting and stopping the motion in precise intervals at precise locations. Indexing is applied generally to either linear or rotary applications.

In machine design applications, indexing can take many forms including Ratchet & Pawl, Geneva Mechanism and more. However these mechanisms have their own inherent limitations and hence are not the choice of a good designer or machine builder anymore.

Cam Indexing?

Cam Driven Indexers convert constant rotary motion at the input shaft into intermittent rotary motion at the output shaft.

This motion is achieved by the combination of the Cam, driven generally by a motor and reducer, and a Turret attached to the output shaft which contains the cam followers. The whole assembly is generally enclosed in an oil filled box known as Housing.

As the cam rotates, followers on the follower wheel are guided through a path dictated by the shape of the cam. During specific portion of the input rotation, the cam confines the followers (and therefore, the output) to a rigid, stationary position called Dwell. During the remainder of the camshaft rotation, the cam geometry causes the followers to move and the output to rotate. This movement is called an Index.

The turret can be made to Index round between stopping positions or oscillate between two stops. The cam can be stopped and restarted when the turret is at rest to extend cycle times. As the cam is rotated at a constant speed, the output stops and starts (i.e. dwells and indexes) in a repetitive pattern.

When turrets are required to index first one way then the other, the mechanism is called as an ‘Oscillator’.

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