Bearing Features

Areas of Application

AXRY-NGX (NGX-SBI) bearings are suitable for applications requiring high load-capacity, ultra-precise and play-free high-rigidity bearings. Typical applications include:

• Milling machining center rotary tables
• Milling heads
• Swivel axes

To fully leverage the advantages of the NGX series, the design of the adjacent construction is also important. The overall shaft system must be considered, including fits and connection part precision, to achieve optimal results.

Accuracy Requirements

For higher accuracy requirements, NGX and NGX-SBI series are available with more tightly restricted axial and radial runout accuracy.

The inner ring and axial washer have identical axial runout characteristics.

Measuring Systems

AXRY-NGX bearings can be equipped with inductive angle measurement systems. These systems are available in incremental or absolute versions, offered as single-head or multi-head systems in various accuracy grades.

myonic only provides the "mechanical part" - the bearing including installed measuring ring and threaded outer ring for axial or radial scanning head mounting.

By mounting the measuring ring directly on the bearing ring, concentricity errors relative to the shaft (table) are minimized, achieving highest accuracies of a few angular seconds.

More information: Axial/Radial Bearing Angle Measurement Systems →

Run-in Cycle - Lubrication / L120 / Gxxx

Fig: Run-in cycle diagram

For grease lubrication, a run-in cycle should be performed during commissioning to distribute the grease in the bearing. Only after complete distribution can the bearing achieve full functionality.

For slowly running swivel axes, no run-in cycle is required.

Lubrication Variations

Grease Lubrication

Standard grease uses special grease per DIN 51825-KPH-C1N-30.

AXRY-NGX bearings are relubricated via the outer ring, NGX-SBI via the inner ring. We generally recommend annual relubrication. After relubrication, a run-in cycle is recommended.

More grease lubrication information: Technical Basics - Lubrication →

For relubrication quantities, please contact the myonic application engineering team.

Oil Lubrication

Of course, AXRY-NGX (NGX-SBI) bearings can also be oil lubricated. These bearings are typically connected to a central oil lubrication system. Use suffix -L120 to obtain grease-free bearings (corrosion protection only).

Lubrication Bores / Lubrication Grooves

Inner Ring Rotation (NGX)

Fig: NGX inner ring rotation lubrication configuration

NGX bearings for inner ring rotation can be lubricated via the radial annular groove on the outer ring or axially. For correct positioning of the bearing lubrication bore with the machine housing lubrication bore, the bearing is equipped with a locating pin hole. (See Positioning Holes section)

For relubrication via the outer ring/inner ring lubrication groove, it is recommended to completely fill the lubrication groove with grease before installing the bearing. This allows grease to enter the bearing more quickly during relubrication. The housing lubrication channel should be close to the bearing's radial lubrication bore.

Outer Ring Rotation (NGX-SBI)

Fig: NGX-SBI outer ring rotation lubrication configuration

NGX-SBI bearings for outer ring rotation can be lubricated via the radial annular groove on the inner ring.

For relubrication via the lubrication groove, it is recommended to completely fill the lubrication groove with grease. The bearing lubrication bore should be close to the housing lubrication channel.

Height Tolerances H1 and H2

Fig: Height tolerances H1 and H2 diagram

Height dimensions H1 and H2 come standard with restricted tolerances up to bearing size 460. Sizes 580 and 650 have restricted tolerances as an option.

H1 - Table Position

Restricted height variation provides the following advantages:

• Labyrinth seal gap can be optimally adjusted against coolant penetration from machining area
• Clamping gap can be optimally adjusted

H2 - Adjacent Construction Below Bearing

H2 refers to the adjacent construction below the bearing, for example for adjusting worm gear clearance.

For exact tolerances, please refer to product tables.

Custom Bearing Adjustment AC

Fig: Support ring configuration diagram

AXRY-NGX (NGX-SBI) bearings can be installed as exposed bearings or with full-surface support. If the L-ring is fully surface-supported by a support ring, the bearing's tilting rigidity can increase by approximately 15-20% (when using standard bearings without -AC suffix).

To prevent bearing friction torque increase, bearing alignment can be adjusted (suffix -AC). If using a normally aligned bearing with supported L-ring, bearing friction torque will significantly increase.

Support ring height should be at least twice the axial washer height.

Support Ring Geometry Recommendations for Maximum Rigidity

Custom Design Jxxxx

myonic offers custom designs indicated by J and a four-digit number.

Bearings with J numbers may include the following additional features:

• Application-specific preload values
• Special markings or packaging instructions
• Custom designs

Limiting Speed n_G

The limiting speeds given in product tables can be achieved for the selected axial/radial bearing in oscillating operation or short-term continuous operation. During prolonged operation in the limiting speed range, bearing temperature will gradually increase. For high-speed applications such as milling/rotary tables, AXRY-NGS design bearings are recommended.

Limiting speeds are guide values determined on a test bench under the following conditions:

• Grease distribution run per specification (see Run-in Cycle)
• Maximum bearing temperature rise of 40 K in raceway area
• NGX without bearing cooling
• Bearing fully bolted, no external loads, only preload and mounting weight

To achieve these limiting speeds, the adjacent construction guidelines must be strictly followed.

Friction and Temperature

Fig: Friction and temperature relationship diagram

During prolonged high-speed operation, factors causing increased bearing friction and temperature must be avoided or compensated. The entire shaft system including all drives must be considered.

Shaft friction torque is mainly influenced by:

• Bearing friction torque - After assembly and full bolting, the bearing is radially and axially play-free and preloaded. Preload is a factor in achieving specified rigidity but simultaneously generates friction torque.
• Lubricant used - In high-speed applications, bearing lubricant must be carefully selected. Only a few greases with relevant viscosity are suitable for higher speeds.

The following points must be noted when designing shaft and assembly to minimize friction torque and temperature increase:

• Geometric errors in adjacent construction cause bearing deformation, resulting in higher friction torque
• Asymmetric housings deform when heated, increasing bearing preload
• Assembly errors may cause friction torque increase
• Contact seals increase friction torque and transfer additional heat to the system
• High acceleration and strong braking may introduce additional friction through moments of inertia
• Machining forces, eccentric clamping and high loads increase friction torque
• Heat input from drives should be minimized