Overview
AXRY bearings can be fitted with inductive angle measuring systems. These systems are available in incremental (MI) or absolute (MA) versions, as single or multi-head systems with various accuracy levels.
By mounting the measuring ring directly onto the bearing ring, concentricity errors relative to the axis (table) are minimized, enabling highest accuracies of a few angular seconds.
myonic only supplies "the mechanical part", i.e. the bearing including the mounted measuring ring and thread in the outer ring for axial or radial scanning head mounting.
Advantages
myonic, in cooperation with Heidenhain (AMO), supplies bearing-integrated absolute and incremental angle measuring systems. The measuring ring is directly mounted onto the bearing. As standard, the measuring ring is mounted on the inner ring, as the inner ring is fitted to the shaft.
Due to myonic's extremely precise manufacturing tolerances, the housing surface on which the measuring ring is mounted runs almost concentrically with respect to the table center. This increases system accuracy and thus the overall accuracy of the axis. As measurement is taken close to the workpiece, deviations due to torsion or tilting are almost completely avoided.
AMO Measuring System Advantages
- Inductive system - No magnetic or optical components used
- High accuracy/high speed - Suitable for ultra-precision and high-speed applications
- Direct mounting - No separate bearing required (no additional friction/heat, maximum hollow shaft)
- No encapsulation required - Standard IP67 protection rating
- Resistant to electromagnetic interference - Measuring unit is non-magnetic, completely resistant to EMI fields
Open System
myonic has developed a new generation of absolute measuring heads and has deliberately designed this development to be open. All manufacturers and users can procure these systems directly from Heidenhain (AMO).
This guarantees unrestricted access to these systems for all users. When choosing the measuring head, there is no need to be tied to a single roller bearing manufacturer.
Measuring Accuracy
System Accuracy
The accuracy of the angle measuring device when fully assembled only on the AXRY bearing.
Main influencing factors:
- Pitch accuracy of the measuring ring (+/-3um or +/-5um)
- Eccentricity error of the measuring ring (1/2 inner ring radial runout)
- Interpolation error of the measuring head (IPF-AMO)
Total Accuracy
The accuracy of the angle measuring device when fully assembled on the machine axis.
Main influencing factors:
- Axis deformation (tilting, etc.)
- Form and dimensional deviations of customer axis and surrounding structure
- Installation errors
Practical Application Accuracy: The larger the bearing, the easier it is to achieve high system accuracy. Using multi-head solutions, accuracies of less than +/- 1 arcsec have been achieved in practical applications. Measuring heads are available for different input frequencies to meet both ultra-precision and high-speed application requirements.
Available Systems
Measuring systems can be installed on most axial-radial bearings of the AXRY-NGX / AXRY-NGS and AXRY-EX construction series.
Incremental Systems (MI)
- Single and multi-head solutions
- Miniature measuring head with external electronics
- Or measuring head with integrated electronics
Absolute Systems (MA)
- Single and multi-head solutions
- Modular measuring head
- Axial or radial mounting options
- When radially mounted, the measuring head is mounted on the housing surface of the bearing outer ring, eliminating complex air gap adjustment
Note: Due to the measuring ring height of 10mm (incremental) or 14mm (absolute), the structural height of smaller and medium-sized bearings increases. See product tables for details.
Function: Incremental vs. Absolute Systems
The measuring ring permanently mounted on the bearing contains a measuring track and a reference track. The measuring track represents the measuring body, on which high-precision periodic pitch is etched using photolithography. These scale marks or increments are counted by the measuring head as they pass, but the absolute position is unknown.
Incremental Systems
In incremental systems, the absolute position is obtained through distance coding on the reference track. By passing 2 adjacent reference marks, the system can determine the absolute position. The required angle depends on the size; typically less than 30 degrees.
Absolute Systems
In absolute systems, a second absolute pitch division runs parallel to the incremental pitch division, continuously providing constant absolute position to the control system.
| Characteristic | Incremental (MI) | Absolute (MA) |
|---|---|---|
| Encoding Method | Incremental counting + distance-coded reference | Absolute position encoding |
| Position on Power-up | Reference travel required (<30 degrees) | Immediately known |
| Measuring Ring Height | 10 mm | 14 mm |
| Maximum Accuracy | +/-2 um arc length | +/-1 um arc length |
Connection to Control System
myonic works closely with Heidenhain (AMO) on all measuring system electronics. This enables efficient connection to a wide variety of control systems, cable outlets, cable lengths, threading, etc. Prototype solutions can be implemented at short notice.
The best expertise on both mechanical and electronic aspects is available from a single source.
Delivery Condition
myonic only supplies "the mechanical part", i.e. the bearing including the mounted measuring ring and thread in the outer ring for axial or radial scanning head mounting.
Standard Configuration
- Bearing is ready for installation of up to 2 measuring heads (can be mounted axially or radially on the outer ring)
- Required mounting threads are located on the outer ring (2 each for axial and radial)
Measuring Head Procurement
Measuring heads can be procured directly from Heidenhain (AMO).
Optional Configuration
If required, only the bearing suitably prepared for measuring ring installation can be supplied.