1 Model Information & Technical Parameters

Model：BTW 75 CTN9/SP

Dimensions

Bore d：75 mm

Outer diameter D：115 mm

Height H：48 mm

Contact angle：60°

Number of rows：2 rows of balls

Axial load capacity：Bidirectional

Housing washer type：Two-piece design for double row angular contact thrust ball bearing

Outer ring locating shoulder：None

Re-lubrication facility：Not available

Accuracy class: SP precision grade

Structure series: Standard BTW series

Seal: Open design, no seals

Surface coating: Uncoated

Pre-lubrication: No lubricant supplied from factory

Code Explanation

BTW: Double row angular contact thrust ball bearing with two-piece housing washer, 60° contact angle, bidirectional axial load capacity, dedicated spindle thrust bearing for machine tools.

75: Nominal matching shaft diameter 75 mm.

C: Standard internal geometry configuration.

TN9: High-performance non-metallic cage optimized for medium-high speed dynamic performance.

SP: Precision accuracy grade to satisfy axial precision requirements of precision heavy-duty machine tool spindles.

Load & Speed Data

Basic dynamic load rating Cr：39.7 kN

Basic static load rating C0r：116 kN

Permissible speed, grease lubrication：6 300 r/min

Permissible speed, oil-air lubrication：7 500 r/min

Material & Additional Properties

Rolling element material: Bearing steel

Indicative carbon footprint：5.3 kg CO₂e

Net weight：1.44 kg

eClass code：23-05-10-02

UNSPSC code：31171531

Suffix Explanation

BTW: Double row angular contact thrust ball bearing with separated two-piece housing washers, 60° large contact angle, capable of supporting axial loads in both directions, applied for spindle axial positioning. Not suitable for heavy radial loads.

75: Reference shaft journal dimension 75 mm.

C: Standard internal construction.

TN9: Modified polymer non-metallic cage, low friction, reduced heat generation at medium-high speed, good impact resistance.

SP: Precision dimensional and axial rotational accuracy, minimizing spindle axial play to guarantee end face quality of machined workpieces.

Important reminder: BTW thrust ball bearings are designed primarily for bidirectional axial loads and can only accommodate minimal radial load. Complete spindle assemblies require combination with radial bearings (NN series double row cylindrical roller bearings). No locating shoulder on outer ring; axial limitation relies on bearing housing. Without built-in lubrication grooves, continuous on-line re-lubrication during operation is not supported, suitable for periodic maintenance lubrication. Open bearing without integral seals; labyrinth seals or oil seals must be installed on housings to block coolant and dust. No pre-filled grease on delivery.

Alternative variants:

BTW75 CTN9/UP (UP ultra-precision grade for ultra-precision heavy-duty mirror grinding spindles)

BTW75 CTN9 (Standard accuracy for general heavy machinery non-precision spindles)

2 Structure & Operating Characteristics

BTW 75 CTN9/SP is SP precision grade double row angular contact thrust ball bearing with 60° contact angle, two-piece housing washer construction and TN9 non-metallic cage for bidirectional axial load bearing. The large 60° contact angle greatly improves axial rigidity and suppresses spindle axial play. Double row ball arrangement ensures uniform load distribution and excellent resistance to alternating axial loads. It delivers upgraded load capacity and fits medium and large heavy-duty spindles.

Core features: 60° large contact angle + bidirectional axial support + SP precision axial accuracy + TN9 medium-high speed cage. Classic spindle matching scheme: NN series double row cylindrical roller bearing for radial support plus BTW thrust bearing for axial positioning for heavy-duty precision machine tools.

Selection guide:

BTW75 CTN9/SP (SP precision grade for large machining centers, heavy cylindrical grinders, precision lathe spindles, heavy-duty precision cutting)

BTW75 CTN9/UP (UP ultra-precision grade for ultra-precision heavy-duty grinding and mirror finishing requiring ultra-low axial runout)

BTW75 CTN9 (Normal precision for general heavy rotating equipment without strict accuracy demand)

3 Core Performance Advantages

1. 60° large contact angle delivers high axial rigidity, effectively controlling spindle axial play and improving workpiece end face accuracy.

2. Double row ball with two-piece housing washer structure accepts axial force in two directions to realize bidirectional spindle axial positioning.

3. TN9 non-metallic cage provides superior dynamic balance, low churning heat, suitable for medium-large heavy-duty spindle systems.

4. SP precision grade ensures high axial rotational accuracy for heavy-duty precision cutting and grinding applications.

5. Mature standard BTW series design with good interchangeability with existing spindle unit components.

6. Enhanced load capacity to withstand alternating axial loads generated during heavy cutting processes.

4 Typical Application Fields

4.1 Spindles of large vertical & horizontal machining centers

Combined with NN double row cylindrical roller bearings to bear bidirectional axial loads

4.2 Precision spindles of heavy internal/external grinders, tool grinders

Restrain axial vibration to stabilize grinding surface and end dimension accuracy under heavy loads

4.3 Main spindles of medium & large precision CNC lathes

Adapt to alternating axial loads generated during heavy forward and reverse turning

4.4 Heavy-duty high-precision rotary fixtures, large precision indexing heads for automation equipment

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

SP precision bearings should be assembled in clean dust-controlled workshops. Thoroughly clean contaminants on shaft shoulders, housing bores and spacer contact surfaces. Pay attention to installation direction of two-piece washers to prevent ball misalignment. Hammer striking directly on balls or cage is forbidden. Without outer ring locating shoulder, axial restraint is achieved via bearing housing; ensure full flat contact of washer mating surfaces. The bearing mainly sustains axial loads; radial loads should be transferred to matched cylindrical roller bearings. No built-in re-lubrication grooves, continuous running oil supply during operation is unavailable; lubricant shall be refilled during scheduled maintenance. Equip housings with labyrinth seals or oil seals against contaminant ingress.

5.2 Selection Guidance

Heavy-duty precision machine spindle, paired with NN double row cylindrical roller bearing, bidirectional axial positioning required → BTW75 CTN9/SP

Ultra-precision heavy-duty mirror machining, extremely low axial play demanded → BTW75 CTN9/UP

General heavy mechanical rotating structure without high precision requirements → BTW75 CTN9

Important notice: Never use BTW thrust bearing alone to carry radial loads, otherwise uneven ball loading and premature fatigue failure will occur. Absence of continuous re-lubrication structure means reasonable maintenance intervals are necessary for long-term continuous operating equipment.

5.3 Lubrication Maintenance Instruction

No lubricant pre-filled at factory. Grease lubrication and oil-air lubrication are both applicable. Without annular lubrication grooves, non-stop on-line oil replenishment cannot be realized; lubricant should be added during periodic equipment shutdown. Continuously monitor spindle axial vibration and temperature rise; inspect lubrication supply system when abnormal heating appears. Due to larger dimensions, thermal monitoring is especially critical for this bearing size.

5.4 Environmental Application Notes

Open construction without built-in seals; reliable sealing devices must be fitted on bearing housings. Balls and raceways are sensitive to dust and coolant erosion; contaminant penetration quickly causes pitting and permanent accuracy loss. Avoid long-term exposure to sustained extreme high temperature to slow TN9 cage aging.

6 Fault Identification

Common failure modes: Unstable workpiece end dimension, excessive spindle axial play, temperature rise under medium-high speed, periodic abnormal noise, ball indentation, raceway fatigue spalling. Typical root causes: Excessive radial load inducing one-sided loading; insufficient lubrication leading to dry friction; tilted washer assembly creating biased load; seal failure causing foreign particle scratches on raceways; permanent plastic deformation exceeding basic static load under heavy operation. Shut down equipment immediately upon accuracy deterioration, abnormal noise or overheating. Bearings with permanent damage on raceways, balls or cage must be fully replaced.