New project — Servo or AC gear motor (fixed stop) for your indexer? Servo isn’t automatically better. Pick the right tool for the job. Here’s a fast, practical guide to decide in ~2 minutes.
Start with the application
- Stations & layout: More stations or nonstandard indexing angles favor servos. Simple, repeatable station counts (4, 6, 8…) often suit fixed-stop indexers.
- Changeover: If you need frequent, tool-less changeover or half-step positioning for fixture-free setups, choose a servo.
- Motion profile: Smooth acceleration/deceleration, dwell-based timing, rhythmic moves with varying speeds → servo. Simple move‑and‑stop cycles with constant timing → fixed stop.
- Cycle time & throughput: High throughput with complex timing or synchronized peripheral motion → servo. Moderate throughput with fixed dwell → fixed stop.
- Integration & synchronization: Tight machine-wide sync (cams, robots, vision) → servo. Standalone dial with basic I/O timing → fixed stop.
Practical trade-offs at a glance
- Cost
- Fixed stop: Lower purchase and integration cost.
- Servo: Higher upfront cost (drive, encoder, controller).
- Accuracy & repeatability
- Both can achieve high accuracy and repeatability.
- Flexibility
- Servo: High — variable angles, programmable index profiles, half-index for tool-less changeover.
- Fixed stop: Low — fixed number of indexes per 360°. Some mechanical options exist but not easily changed later.
- Maintenance & reliability
- Fixed stop: Simpler, fewer electronics, often lower maintenance.
- Servo: More components (encoder, drive) — needs proper setup and occasional tuning.
- Setup & commissioning
- Fixed stop: Faster setup; fewer parameters.
- Servo: Longer commissioning but easier to change later via software.
When to choose fixed-stop indexers
- Price-sensitive projects with predictable, repetitive indexing.
- Machines where simplicity and uptime are priorities.
- Environments where fewer electronics are desired.
(Example: simple rotary assembly where each station performs identical, time-fixed work.)
When to choose servo indexers
- Complex part flow, irregular indexing angles, or frequent changeovers.
- Need for coordinated motion with robots, conveyors, or vision systems.
- Projects that benefit from future-proofing and software-driven flexibility.
(Example: multiple tool changes per part or synchronized pick-and-place tasks.)
Useful product references
- For compact servo-capable indexers and modular systems, see Sankyo Automation’s RU series (good for flexible, high-precision servo applications): https://sankyoautomation.com/ru-series/
- For robust, simpler fixed-stop and mechanical-style indexers, see Sankyo’s AD series (cost-effective, durable designs): https://sankyoautomation.com/ad-series-cam-indexing-drive-table/
Final tip
If budget allows and future flexibility is likely, invest in a servo — you’ll pay more now but save time on changeovers and upgrades. If requirements are stable and cost/uptime dominate, a fixed-stop indexer is the pragmatic choice.
Need a quick consult to pick for your machine? Tell me: stations, cycle time, and changeover frequency — I’ll recommend the best platform.