DT Cam Indexer: Structure, High-speed or low-speed?

What is a DT cam indexer?

In the world of precision intermittent motion, the DT-type cam indexer — also called a dial-type indexing unit or cam-driven dividing table — converts continuous rotary input into repeatable, locked-position step outputs. Unlike the more widely discussed DF-type globoidal cam indexer, the DT design uses a face-plate (end-face) conjugate cam paired with roller followers. This combination drives a rigid output flange through a defined index angle. Then it holds the flange absolutely stationary during the dwell period.

The mechanism sits at the crossroads of precision mechanical design and industrial automation efficiency. Its core assembly includes a face conjugate cam, a hardened steel output dial, needle-bearing roller followers, and a self-locking dwell zone machined directly into the cam profile. No external brake or servo hold is required during the stationary phase. Instead, the geometry itself provides the lock. As a result, the bill of materials stays lean and control-cabinet complexity is reduced on automated assembly lines.

Four defining structural characteristics of DT Cam Indexer

High-speed or low-speed? The honest answer for DT Cam Indexer

Engineers often overestimate the speed ceiling of the DT-type cam indexer. The face-cam geometry produces a sharper acceleration curve than a globoidal cam surface. As a result, roller-follower impact forces climb steeply with input RPM. Beyond roughly 60 rpm, dynamic loading accelerates needle-bearing wear. Additionally, the cam profile’s modified sine relief becomes insufficient to dampen vibration at the transition zones.

The sweet spot for a DT indexing drive sits between 10 and 60 rpm input speed, translating to cycle times of approximately 1.5 to 6 seconds per station depending on the motion-to-dwell ratio selected. Within this band, the unit delivers the best combination of positioning repeatability, component longevity, and torque density.

For cycle times below 1.5 seconds or index counts above 16, engineers should evaluate a DF globoidal cam indexer or a direct-drive servo rotary table instead. The globoidal cam wraps the follower path across a three-dimensional surface. This distributes load more evenly and supports input speeds up to 200 rpm in comparable frame sizes.

Selection shortcut: Cycle time ≥ 2 s, station count ≤ 12, heavy payload or flat-mount installation → DT cam indexer is the right call. Cycle time < 1.5 s or station count > 12 → evaluate DF-type or servo direct-drive rotary indexing table.

Industrial automation case studies with DT Cam Indexer