1 Model Information & Technical Parameters

Model：BTM 85 BT/P4CDBA

Dimensions

Bore d：85 mm

Outer diameter D：130 mm

Height H：40.5 mm

Contact angle：40°

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: Modified P4C precision grade

Structure series: High-speed optimized BTM series

Seal: Open design, no seals

Surface coating: Uncoated

Pre-lubrication: No lubricant supplied from factory

Code Explanation

BTM: High-speed double row angular contact thrust ball bearing with two-piece housing washer, 40° contact angle, bidirectional axial load capacity, dedicated high-speed spindle thrust bearing.

85: Nominal matching shaft diameter 85 mm.

BT: Optimized internal geometry for high-speed operation.

P4C: Improved P4 precision specification for high-speed precision spindle applications.

DBA: Standard tolerance benchmark configuration for matched spindle unit assembly.

Load & Speed Data

Basic dynamic load rating Cr：40 kN

Basic static load rating C0r：88 kN

Permissible speed, grease lubrication：6 400 r/min

Permissible speed, oil-air lubrication：8 300 r/min

Material & Additional Properties

Rolling element material: Bearing steel

Indicative carbon footprint：6.2 kg CO₂e

Net weight：1.67 kg

eClass code：23-05-10-02

UNSPSC code：31171531

Suffix Explanation

BTM: High-speed oriented double row angular contact thrust ball bearing with separated two-piece housing washers and 40° contact angle, capable of bidirectional axial loads. Compared with thrust bearings of larger contact angle, it delivers higher limiting speed with moderate axial rigidity, targeting high-speed operation rather than extreme heavy axial load conditions.

85: Reference shaft journal dimension 85 mm.

BT: Optimized internal profile to reduce friction loss at high rotating speed.

P4C: Enhanced P4 precision grade with improved dimensional and axial rotational accuracy, suppressing axial vibration under high speed.

DBA: Factory standard tolerance configuration to satisfy matched assembly of spindle modules.

Important reminder: BTM series thrust ball bearings are mainly designed for bidirectional axial loads and can only withstand minimal radial load. Complete spindle assemblies must adopt radial bearings (NN series double row cylindrical roller bearings) in combination. No locating shoulder on outer ring; axial restraint relies entirely on bearing housing. Without built-in lubrication channels, continuous on-line re-lubrication during running is impossible, suitable for periodic maintenance lubrication. Open bearing without integral seals; oil seals or labyrinth seals shall be installed on housings to block coolant and dust. No pre-filled grease upon delivery.

Alternative variants:

BTM85 BT/P4BA (Standard P4 precision general version)

BTM85 BT/P2 (Ultra-precision P2 grade for ultra-high precision high-speed spindles)

BTM85 BT (Normal precision for general high-speed rotating machinery)

2 Structure & Operating Characteristics

BTM 85 BT/P4CDBA is modified P4C precision grade high-speed double row angular contact thrust ball bearing with 40° contact angle, two-piece housing washer construction and non-metallic cage for bidirectional axial load support. The moderate 40° contact angle is preferred for high-speed spindles, balancing maximum rotational speed and axial rigidity, and achieves better temperature control than thrust bearings with larger contact angles. Double row ball layout ensures uniform load distribution and good resistance to alternating bidirectional axial force.

Core features: 40° contact angle + BTM high-speed series design + P4C precision axial accuracy + low-heat non-metallic cage. Classic spindle matching scheme: NN series double row cylindrical roller bearing for radial support paired with BTM thrust bearing for bidirectional axial positioning, standard configuration for high-speed machining centers.

Selection guide:

BTM85 BT/P4CDBA (Modified P4C precision grade for high-speed machining centers, high-speed CNC lathes, cylindrical grinders requiring balanced speed and precision)

BTM85 BT/P2 (P2 ultra-precision grade for ultra-high speed precision grinding and mirror finishing equipment)

BTM85 BT (Normal precision for general high-speed rotary fixtures and non-precision transmission mechanisms)

3 Core Performance Advantages

1. Optimized 40° contact angle reduces heat generation under high-speed operation, offers superior limiting speed performance while retaining proper axial rigidity.

2. Exclusive BTM high-speed internal structure lowers rolling friction, suitable for prolonged continuous high-speed rotation.

3. Double row ball with two-piece housing washer structure accepts axial loads in both directions to realize bidirectional spindle axial limitation.

4. Enhanced P4C precision grade minimizes spindle axial play and vibration at high speed, stabilizing dimensional accuracy in finishing processes.

5. Non-metallic cage cuts churning loss at high speed, restricts temperature rise and extends service life of lubricants.

6. Standardized two-piece housing washer design ensures good interchangeability with existing spindle components for convenient maintenance replacement.

4 Typical Application Fields

4.1 Spindles of high-speed vertical & horizontal machining centers

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

4.2 Precision spindles of high-speed internal/external grinders and tool grinders

Restrain high-speed axial vibration to stabilize accuracy of ground workpieces

4.3 Main spindles of high-speed precision CNC lathes

Adapt to alternating axial loads generated during high-speed turning

4.4 High-speed precision rotary fixtures and automatic precision indexing devices

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

P4C precision bearings should be assembled in clean dust-controlled workshops. Remove all contaminants on shaft shoulders, housing bores and spacer mating surfaces. Observe installation orientation of two-piece washers to avoid ball displacement. Direct hammer impact on balls or cage is strictly forbidden. No outer ring locating shoulder; ensure flat full contact of washer surfaces and achieve axial limitation via bearing housing. Load sharing principle: radial loads shall be transferred to matched cylindrical roller bearings, this bearing only undertakes axial force. Without built-in re-lubrication grooves, continuous running oil supply is unavailable; lubricant replenishment shall be arranged during periodic shutdown maintenance. Equip bearing housings with oil seals or labyrinth seals to prevent dust and coolant from entering raceways.

5.2 Selection Guidance

High-speed precision spindle matched with NN double row cylindrical roller bearing, bidirectional axial positioning required, balance of speed and precision needed → BTM85 BT/P4CDBA

Ultra-high speed mirror precision machining requiring ultra-low axial runout → BTM85 BT/P2

General high-speed rotating equipment without strict precision requirements → BTM85 BT

Important notice: Never use BTM thrust bearing alone to support radial loads; uneven ball loading will trigger premature fatigue spalling. Absence of continuous on-line lubrication structure requires reasonable maintenance intervals for long-term continuously 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 passages, non-stop on-line oil replenishment cannot be realized; lubricant filling must be completed during scheduled machine shutdown. Continuously monitor spindle temperature rise and axial vibration, inspect lubrication system immediately when abnormal heating occurs.

5.4 Environmental Application Notes

Open construction without built-in seals; reliable sealing devices must be mounted on bearing housings. Balls and raceways are sensitive to erosion from dust and coolant. Contaminant intrusion easily causes raceway scratches and pitting, leading to rapid accuracy loss. Avoid long-term sustained ultra-high temperature operation to slow aging of non-metallic cage.

6 Fault Identification

Common failure modes: Fluctuating workpiece end dimension, excessive spindle axial play under high speed, abnormal temperature rise during operation, periodic abnormal noise, ball indentation, raceway fatigue spalling. Primary causes: Extra radial load leading to one-sided biased loading; insufficient lubrication causing dry friction; uneven stress caused by tilted installation of two-piece washers; seal failure allowing foreign particles into raceways; permanent plastic deformation from overload exceeding basic static load. Shut down equipment immediately once accuracy degradation, abnormal noise or overheating appears. Bearings with permanent damage on raceways, balls or cage must be replaced as a whole.