7305BDB Duplex Back-to-Back Angular Contact Ball Bearing 25x62x34mm 40° Contact

1. Product Overview

7305BDB is factory pre-matched duplex back-to-back (DB) paired single row angular contact ball bearing set, standard ISO dimension 25mm inner bore × 62mm outer diameter × 34mm total paired width, each single unit width 17mm.

Model code full explanation:

• 7305: Medium heavy series single row angular contact ball bearing base model
• B: 40° large contact angle design, superior bidirectional axial load capacity
• DB: Back-to-back duplex matched arrangement, two bearings ground flush on back faces, pre-set internal preload before delivery, cannot mix with other single bearings

Two 7305B single bearings are precisely paired and ground as one integral set. Back-to-back layout creates long distance between effective load centers, providing ultra-high rigidity against overturning moment, simultaneously supporting radial load and bidirectional heavy axial load. Inner ring, outer ring and steel balls adopt high purity 52100 chrome bearing steel, equipped with lightweight stamped steel riveted cage. Open non-sealed design, compatible with circulating oil lubrication for high-speed spindle equipment. Widely used in CNC machine tool spindles, hydraulic pump drive shafts, heavy-duty gear reducers, compressor rotors, printing machinery main shafts and all transmission structures requiring high rigidity and bidirectional axial positioning.

2. Technical Specifications

3. Core Advantages

1. DB back-to-back matched layout, long effective load center span, outstanding anti-overturning moment rigidity, ideal for shafts subjected to radial load + bidirectional axial load + bending moment simultaneously.
2. 40° large B contact angle, far stronger bidirectional axial bearing capacity than 30° A type, stable positioning under alternating forward/reverse axial impact load.
3. Factory flush grinding & integral pre-matching, fixed consistent preload out of package, eliminate on-site clearance adjustment work, guarantee uniform rotation accuracy without mixing individual single bearings.
4. High purity quenched 52100 chrome steel components, uniform metallographic structure, excellent contact fatigue resistance, long service life under continuous high-speed alternating load.
5. Ultra-precision superfinishing raceway and steel ball surfaces, ultra-low vibration and low runout performance, meet precision machine tool spindle rotation accuracy requirements.
6. Open through-type design without sealing barrier, smooth circulating oil flow inside bearing, fast heat dissipation, avoid high-temperature grease carbonization and bearing ablation failure during long high-speed operation.
7. Standard ISO metric interchangeable dimension, fully compatible with global 7305BDB duplex matched bearing sets, direct replacement without modifying spindle housing and shaft structure.
8. Rich customizable options: P4 high precision spindle grade, medium/heavy preload adjustment, single/double-side contact seal upgrade, brass machined cage, OEM laser marking on outer ring, neutral export anti-rust carton packaging, high-temperature extreme pressure lubricant pre-filling.

4. Application Scenarios

7305BDB preloaded back-to-back duplex angular contact bearing set is high-rigidity bidirectional positioning rotary spare part matched with 25mm shaft heavy precision transmission equipment:

• CNC lathe, milling machine, machining center main spindle support bearing assemblies
• High-pressure hydraulic pump, plunger pump drive shafts rotary positioning units
• Heavy-duty helical gear reducer, planetary gearbox input/output shaft bearing positions
• Air compressor, refrigeration compressor rotor high-speed support components
• Printing press, paper machinery main transmission long shaft bearing sets
• Precision testing instrument, optical equipment rotating positioning assemblies

Aftermarket interchangeable 7300 series B-type DB duplex matched angular contact ball bearing

High rigidity moment-resistant paired bearing solution for machine tool spindle manufacturers, hydraulic equipment OEM factories and heavy reducer bulk maintenance procurement.

5. Why Choose GQZ Bearing

We have 25 years of mature professional manufacturing experience for 7300 series B-type DB duplex pre-matched angular contact ball bearings including 7305BDB 25mm bore spindle models.

Our 7305BDB bearing sets adopt unified international ISO standard metric dimensions, consistent duplex flush grinding preload parameters, chrome steel heat treatment and cage stamping precision standards, fully dimensionally interchangeable with global original brand spindle matched bearings.

Complete OEM & ODM customized service system, supporting multi-precision grades, light/medium/heavy preload adjustment, sealing structure transformation and brass high-speed cage personalized requirements.

Strict pre-delivery full quality inspection flow: 52100 steel raw material composition and hardness test, steel ball automatic sorting screening, long-cycle high-speed alternating axial moment rotation aging test, duplex matching flush grinding tolerance full batch inspection.

Professional spindle angular contact bearing technical team provides one-to-one radial-axial-moment combined load calculation, spindle preload installation tolerance design and circulating oil cooling lubrication maintenance guidance within 24 working hours.

Standardized precision duplex bearing production workshop provides competitive factory direct bulk wholesale price, stable long-term mass supply for global machine tool, hydraulic pump and heavy reducer machinery spare parts purchasers.

We specialize in DB back-to-back preloaded matched angular contact bearing sets, strict raceway superfinishing and duplex grinding preload quality control, committed to long-term stable win-win cooperation with high-rigidity precision spindle transmission equipment suppliers.

6. Quality Control

• Raw material chemical composition, hardness and fatigue resistance inspection for 52100 chrome steel inner/outer ring and steel ball blanks
• Precision turning forming processing, multiple stress relief tempering cycles, ultra-precision superfinishing grinding for angular contact raceway curved surfaces
• Steel ball high temperature overall quenching, mirror polishing and high precision automatic sorting production line
• Low carbon steel cage stamping & riveting forming process, two single bearings flush back-face duplex grinding matching procedure, preload value detection one by one
• Targeted professional performance testing: 7305BDB long cycle high-speed bidirectional axial moment alternating rotation aging test, spindle high rigidity low runout durability simulation test, preload consistency batch inspection
• Comprehensive re-inspection of overall dimensional tolerance, bore roundness and duplex matching flatness before anti-rust oil coating and export moisture-proof carton packaging.

Each production batch of 7305BDB bearing sets undergoes CNC spindle continuous cycle rotation simulation test to guarantee stable low-vibration high-rigidity bidirectional load rotary support performance for 25mm shaft precision heavy transmission systems.

7. Get A Quote Now

If you need 7305BDB 25x62x34mm DB back-to-back preloaded duplex angular contact ball bearing pairs for machine tool spindle / hydraulic reducer manufacturing, precision transmission assembly and industrial equipment maintenance bulk matching, send your purchase demand directly.

Complete professional one-stop supporting services after sending inquiry:

• Formal official detailed quotation reply within 24 working hours
• One-to-one radial + bidirectional axial + moment combined load calculation, spindle preload installation and circulating oil cooling lubrication technical support provided by professional spindle bearing engineers
• Customized bearing performance upgrade options including P4 high precision grade and heavy preload modification
• Favorable factory direct bulk wholesale price for large quantity single model orders of 7305BDB

Please provide purchase quantity, actual working conditions (continuous high speed / bidirectional alternating axial impact / large bending moment load environment) to obtain complete official quotation documents.

8. FAQ