Inductive Encoder Solutions for Rotary Tables and Precision Rotary Stages
The INEM series from OTV Sensing are high-precision inductive absolute encoders purpose-built for direct-drive rotary tables and precision rotary stages. The inductive sensing principle delivers optical-grade accuracy (±1 arcsec repeatability, 23-bit resolution) with the environmental robustness of magnetic encoders — immune to oil mist, coolant, condensation, vibration and electromagnetic interference. A calibration-free installation with LED air-gap feedback makes INEM the ideal choice for machine tools, semiconductor equipment and aerospace platforms.
What Is a Rotary Table Encoder?
A rotary table encoder is an absolute angle-measurement device mounted directly on the rotating axis of a rotary table or precision stage. The INEM series uses the inductive sensing principle — a passive rotor ring and a stationary stator board — to measure absolute position without a bearing, glass disc or optical readhead. This makes it inherently robust for the oil-mist, coolant and vibration environments of machine tools and semiconductor equipment.
Inductive vs Optical vs Magnetic Encoders
| Feature | Optical | Magnetic / Resolver | INEM Inductive |
|---|---|---|---|
| Accuracy | Very high (±1 arcsec) | Medium / low | Very high (±1 arcsec) |
| Environmental tolerance | Weak (contamination) | Medium (EMI) | Excellent (oil, vibration, EMI) |
| Reliability | Medium | High | Very high |
| Installation | Complex (precision alignment) | Simple | Simple (calibration-free, LED feedback) |
| Cost | Expensive | Economical | Cost-effective |
| Supply chain | High risk | Medium | Fully domestic |
Why Engineers Choose INEM Rotary Table Encoders
Optical-Grade Accuracy
±5 arcsec absolute accuracy, ±1 arcsec repeatability and 23-bit resolution — meets the micron-level positioning demands of five-axis machining and semiconductor manufacturing.
Contamination Immunity
Inductive sensing is immune to oil mist, coolant, condensation, vibration and electromagnetic interference — stable operation even in harsh machine-tool environments.
Calibration-Free Installation
Physical clamping only. The built-in LED gives real-time air-gap feedback — no software, no gauges, no precision alignment.
Bearingless Large Through-Bore
Split-ring stator/rotor design with a large hollow bore and ultra-thin profile for direct integration into rotary tables.
100% Domestic Supply Chain
Fully domestically sourced hardware and algorithms — short lead time and fast after-sales, eliminating chip-shortage risk.
Multi-Protocol Interface
RS485, BiSS-C and SSI outputs to suit a wide range of drives and controllers.
Models & Dimensions
| Model | Stator (ID/OD) | Stator thickness | Rotor (ID/OD) | Rotor thickness | Resolution | Accuracy | Repeatability |
|---|---|---|---|---|---|---|---|
| INEM-035 | Φ44.8 / 90 mm | 4.5 mm | Φ35 / 80.2 mm | 4.1 mm | 23-bit | ±5 arcsec | ±1 arcsec |
| INEM-036 | Φ51 / 106 mm | 5.5 mm | Φ36 / 90 mm | 7.1 mm | 23-bit | ±5 arcsec | ±1 arcsec |
| INEM-058 | Φ72 / 128 mm | 5.5 mm | Φ58.75 / 113 mm | 7.1 mm | 23-bit | ±5 arcsec | ±1 arcsec |
Specifications
| General Specifications | |
|---|---|
| Supply voltage | 5 VDC ±5% |
| Current consumption | ≤200 mA |
| Recommended air gap | 0.4 mm ±0.05 mm |
| Turns | Single-turn |
| Shock resistance | 980 m/s², 6 ms |
| Vibration endurance | 10–55 Hz @ 1.5 mm; 55–2000 Hz @ 98 m/s² |
| Operating temperature | -40 to +85 °C |
| Storage temperature | -50 to +125 °C |
| EMC | IEC 600-6-2 / IEC 600-6 |
Where INEM Rotary Table Encoders Excel
High-End CNC Machine Tools
Four- and five-axis machining centers demanding high contour accuracy under oil-mist and vibration.
Semiconductor Equipment
Lithography, wafer inspection and die bonding — nanometer-scale motion control with minimal downtime.
Defense & Aerospace
Satellite observation platforms, radar turntables and inertial test systems with 100% domestic supply.
Precision Rotary Stages
Metrology and automation stages requiring absolute position without homing.
Complete Your Motion Sensing Solution
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