1 Complete Model & Code Explanation

Model: 7013 ACD/P4AQBCA

Code Definition

7013: Light series precision angular contact ball bearing basic dimension

ACD: 25° heavy-duty contact angle, high axial rigidity, strong anti-tilting capacity, moderate limiting speed

P4A: P4A ultra-precision grade

QBCA: Factory DB back-to-back pre-matched bearing set supplied with high-precision load equalizing intermediate spacer

Note: Single bearing:7013 ACD/P4A; DB set without spacer:7013 ACD/P4ADBA; DB set with standard spacer:7013 ACD/P4ADBC; DB set with load equalizing spacer:7013 ACD/P4AQBCA

Matching suffix list: DBA(DB no spacer), DBC(DB standard spacer), QBCA(DB load equalizing precision spacer set)

Standard all-steel bearing without ceramic rolling elements or raceway coating; Extended model:7013 ACD/HCP4AQBCA (hybrid ceramic DB set with load equalizing spacer)

Key Dimensions

Single bearing dimension

Bore d: 65 mm

Outer diameter D: 100 mm

Width B: 18 mm

Contact angle: 25°

Structure: Single row open bearing, set includes 2 matched bearings (DB arrangement) + 1 high-precision load equalizing intermediate spacer

Rolling element: High-carbon chromium bearing steel ball

Ring material: High-carbon chromium bearing steel, ultra-precision mirror grinding

Spacer material: Premium alloy structural steel, ultra-precision grinding on both end faces for excellent parallelism to realize load equalization

Supply form: Complete assembly of two bearings and matched equalizing spacer, factory face-height calibrated for direct DB assembly

Pre-filled lubricant: None

Surface treatment: Bearings with standard mirror finish; spacer with ultra-precision end grinding, no functional coating

Note: Contact SKF for official load ratings and limiting speed data.

Full Product Attributes

Contact form: two-point contact

Number of rows: single row, assembly of two DB bearings plus high-precision load equalizing spacer

Matching mode: factory precision pre-matched DB back-to-back set with dedicated load equalizing spacer

Precision class: P4A ultra-precision grade

Material: All-steel angular contact ball bearing

Seal: Open type, no seal

Note: The 25° ACD contact angle delivers excellent axial load and anti-tilting performance for long-term heavy milling. Compared with DBC standard spacer version, QBCA adopts ultra-precision load equalizing spacer to balance load distribution of two bearings, avoid overload and premature fatigue on single bearing, restrain temperature rise at high speed and achieve better long-term accuracy stability. Standard all-steel construction has no insulation, not applicable to built-in motor spindles with shaft current, optimized for high-precision belt-driven spindles. No raceway coating requires clean lubricant and stable cutting impact.

Open structure eliminates seal drag; continuous oil-air lubrication is preferred. High-speed spindle grease can be adopted for intermittent short-cycle operation. Spindle design must incorporate labyrinth or air curtain dust-proof structure.

2 Structure & Operating Characteristics

Japan NMT 7013 ACD/P4AQBCA assembly consists of two 7013 ACD/P4A bearings and one ultra-precision load equalizing intermediate spacer with factory DB back-to-back matching. All bearing components are made of high-carbon chromium bearing steel with mirror ultra-precision grinding on raceways and balls. The supplied spacer is ultra-precision ground with strictly controlled geometric tolerances, dimensionally matched with paired bearings. The 25° contact angle improves axial stiffness and heavy-load capability. The complete assembly is delivered as one unit, removing the need for on-site spacer selection and grinding, balancing load between two bearings and extending overall bearing service life.

Designed for standardized high-precision belt-driven spindle units of high-end vertical machining centers, precision engraving & milling machines and high-precision internal & external grinders. Suitable for mass assembly of precision equipment requiring stable long-term accuracy, consistent temperature rise and extended bearing service life.

3 Core Performance Advantages

1. 25° ACD heavy-duty contact angle: Outstanding axial load capacity and anti-tilting rigidity, suitable for high-feed continuous heavy milling.

2. P4A ultra-precision grade: Strict runout control to guarantee geometric accuracy of machined workpieces.

3. QBCA factory DB matched set with load equalizing spacer: Bearings calibrated for face height, supplied with ultra-precision equalizing spacer; no on-site spacer fitting or machining required. Balances load sharing of two bearings, prevents unilateral overload, reduces temperature fluctuation and extends bearing service cycle.

4. Mature all-steel construction: Stable supply and controllable lead time.

5. Open non-sealed design: No sealing friction loss, fully compatible with oil-air lubrication for long continuous high-speed operation.

6. DB back-to-back layout with equalizing spacer: High moment stiffness, strong resistance to bidirectional axial load and tilting load, lower operating vibration and superior long-term machining stability.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

P4A precision matched bearing assembly shall be installed in constant-temperature dust-free clean workshop. Remove all burrs, dust and metal debris on shaft and housing mating surfaces. Adopt controlled thermal mounting with limited heating temperature; open flame heating is prohibited. Never strike bearings or spacer to avoid end-face indentation and raceway damage. The complete QBCA assembly must be used as a whole; bearings and spacer cannot be split and mixed with other single bearings, which will invalidate factory matching accuracy and load equalizing coordination.

5.2 Matching & Preload Instructions

Delivered as complete DB back-to-back double bearing kit with matched load equalizing spacer, no re-matching required on site. Assemble strictly following DB orientation, install spacer between outer rings of two bearings. Medium preload recommended for continuous heavy cutting; light preload for light-load finishing. Long-term full-speed operation under heavy preload is forbidden to prevent excessive temperature rise.

Selection guide: ①On-site separate standard spacer preparation →7013 ACD/P4ADBC; ②Demand load balance and long-term stable operation with factory load equalizing spacer →7013 ACD/P4AQBCA; ③Built-in spindle anti-electrocorrosion demand →7013 ACD/HCP4AQBCA hybrid ceramic set with equalizing spacer; ④High-speed light load →18°AC or 15°C matched bearing series.

5.3 Lubrication Matching Solutions

No pre-filled lubricant. Oil-air forced circulation lubrication recommended for long continuous high-speed operation. Special high-speed spindle grease only allowed for short intermittent machining. Install precision filter on oil circuit to keep lubricant clean; hard contaminants easily cause raceway scuffing. Do not mix lubricants of different brands or specifications.

5.4 Speed Parameter Note

Limiting DN speed is lower than 18°AC and 15°C contact angle series. Reserve sufficient speed safety margin under continuous heavy load; long-term operation near limiting speed is not recommended.

6 Daily Maintenance & Fault Troubleshooting

Carry out multi-stage low-speed running-in after assembly; increase speed to rated level only after temperature rise and vibration stabilize. Open bearings have no built-in dust shield; front spindle dust seal cannot be omitted.

Maintain continuous supply of clean lubricant to avoid dry friction caused by oil starvation. In case of abnormal heating, constant noise or sudden vibration, inspect sequentially: oil supply & lubricant cleanliness, over-limit preload, assembly coaxial accuracy, dust seal condition, cutting impact load. For all-steel bearings, strictly manage lubricant cleanliness to delay raceway fatigue pitting.