Fafnir2MM9105WI DUMSuper-Precision Angular Contact Ball Bearing Duplex Pair — 25 mm Bore, 47 mm OD, 12 mm Wide, 15° Contact Angle, Medium Preload, Phenolic Cage

Product Description

What this part is:

Fafnir 2MM9105WI-CR-DUM super-precision angular contact ball bearing, supplied as a matched duplex pair. Bore Diameter: 25 mm. Outside Diameter: 47 mm. Overall Width: 12 mm per bearing. Item Weight: 0.077 kg (0.17 lb) per bearing. Series: 9100WI. Base Number: 9105. Rolling Elements: Ball. Bore Type: Straight. Closure Type: Open. GTIN: 087796072077. The 9105 size code is the ISO 7005 envelope.

Decoding the designation:

2MM — Contact Angle: 15°, in Timken’s MM super-precision spindle range.

MM — Precision Class: ABEC 7 / P4.

9105 — the 25 mm bore size in the 9100 light spindle series, on ISO 7005 boundary dimensions.

WI — low shoulder on both rings.

CR — Cage Material: Phenolic.

DU — Mounting Arrangement: duplex, two bearings ground as one matched set.

M — Preload: Medium.

What these specs mean in practice:

Dynamic Load Rating: 12,900 N. Static Load Rating: 7,400 N. Contact Angle: 15°. A 15° angle favours speed and radial stiffness over thrust capacity, which is the machine tool spindle trade.

Limiting Speed: 30,900 rpm grease; 61,800 rpm oil. Preload: Medium. Precision Class: ABEC 7 / P4. Cage Material: Phenolic, light, self-lubricating and quiet at high surface speeds. Medium preload lifts axial and radial stiffness above the light setting at the cost of some speed headroom.

Mounting data:

Shaft backing shoulder diameter 29.9 mm. Housing backing shoulder diameter 42.6 mm. Maximum housing fillet radius 0.6 mm. The straight bore seats on a ground spindle journal, and the universally ground faces set the preload when the clamp nut is tightened.

Quantity and configuration:

Unit Quantity: 2 Pcs. Number Of Rows: 2. Two bearings ship as one factory-matched DUM set.

Interchange guidance:

The 25 x 47 x 12 mm envelope at 15° is the ISO 7005 C size, so a 15° super-precision 7005 duplex set at medium preload from another maker fits the same seat. The Fafnir 3MM9105WI-CR-DUM shares the envelope at a 25° contact angle.