Fafnir2MM9305WICRDULAngular Contact Ball Bearing – 25 mm ID, 42 mm OD, 9 mm Width, Open, 15° Contact Angle, Light Preload.

Product Description

What this part is

Fafnir 2MM9305WICR-SUL super-precision angular contact ball bearing. Bore: 25 mm. Outside diameter: 42 mm. Width: 9 mm. Series: 9300. Single row, open on both faces. Contact Angle: 15°. The 9300WI series maps to the ISO 719xx extra-light series, so this envelope is the ISO 71905 size, also written 7905.

Decoding the designation

2MM: 15° contact angle. MM prefix: P4S tolerance, ABEC 7 running accuracy with ABEC 9 dimensional accuracy. WI: super-precision spindle execution. CR: machined phenolic cage, riding on the outer-ring land. SU: single bearing, universally ground so any two pieces stack back-to-back, face-to-face or in tandem and reach the marked preload when clamped. L: light preload. Precision Class: P4S (ABEC 7/9). Country of origin on this item: United States.

Published ratings

Dynamic Load Rating: 7.9 kN. Static Load Rating: 5.3 kN. Limiting Speed: 48,000 rpm. Operating temperature range: −30 °C to 120 °C. Running accuracy, radial and axial runout: P4. Item weight: 0.10 lb.

What these specs mean in practice

A 15° contact angle gives the highest speed capability of the standard super-precision angles and the lowest axial stiffness, which is why it is the usual choice for a high-speed grinding or milling spindle. The extra-light 719xx cross-section keeps the ball complement small and the mass low, and it is what allows the 48,000 rpm figure on a 25 mm bore. The outer-land-riding phenolic cage is guided by the outer ring rather than by the balls, so cage motion stays stable at speed, and the 120 °C ceiling is the phenolic material limit.

Quantity and configuration

One bearing, universally matchable. Unit Quantity: 1 Pc. The carton also carries the DUL duplex marking, which is the factory pairing designation for this execution and is a useful search term.

Interchange guidance

Same-envelope 15° super-precision equivalents: SKF 71905 CD/P4A, and in light-preload universally matchable form SKF 71905 CD/P4ADGA; GMN S 61905 C TA A7; NSK 7905C. The ISO base numbers are 71905 and 7905. A 71905 ACD or 7905A5 is a related size on the same 25 x 42 x 9 mm envelope at a 25° contact angle.