Fafnir2MM9104WIDULSuper-Precision Angular Contact Ball Bearing Pair – 20 mm Bore, 42 mm OD, 12 mm Width, 15°, Light Preload

Product Description

What this part is

Fafnir 2MM9104WICRDUL, a super-precision angular contact ball bearing supplied as a universally ground duplex pair. Bore Diameter: 20 mm. Outside Diameter: 42 mm. Overall Width: 12 mm per bearing. Total Width: 24 mm mounted as a pair. Contact Angle: 15°. Rolling Elements: Ball. Number Of Rows: 1 per bearing. Bore Type: Straight. Closure Type: Open. Cage Material: Phenolic. Precision Class: ABEC 7/9 / P4S. Preload: Light. Series: 9100WI. Base Number: 2MM9104WI. GTIN: 087796071902.

Decoding the designation

2MM — Fafnir super-precision spindle range at a 15° contact angle, ground to ABEC 7/9 (P4S) tolerances.

9104 — the 9100 light dimension series, bore code 04, which maps to the ISO 7004 envelope: 20 mm bore, 42 mm outside diameter, 12 mm width.

WI — low shoulder on both rings.

CR — phenolic cage.

DUL — duplex pair, universally ground, light preload. Either face can be brought together, so the pair mounts back-to-back, face-to-face or in tandem.

What these specs mean in practice

Dynamic Load Rating: 11,600 N per bearing. Static Load Rating: 6,010 N per bearing. Limiting Speed: 37,100 rpm grease; 74,200 rpm oil. Item Weight: 0.134 kg (0.30 lb) for the pair. Internal Clearance: N/A — a preloaded set is clamped to a defined stiffness rather than run to a clearance. A small bore in the light 9100 section is what allows the very high speed figure. Light preload is the lowest of the three Fafnir grades and keeps running heat down on a continuously driven spindle.

Mounting data

Shaft Backing Shoulder Diameter: 24.8 mm. Housing Backing Shoulder Diameter: 37.7 mm. Maximum Housing Fillet Radius: 0.6 mm (0.024 in) — the largest housing corner radius the bearing corners will clear.

Quantity and configuration

Unit Quantity: 2 Pcs. One universally ground duplex pair. The 12 mm figure is the width of a single bearing; the pair occupies 24 mm of shaft length when clamped together.

Interchange guidance

Direct super-precision equivalents on the 7004 envelope at 15° with light preload: FAG B7004-C-T-P4S-UL, SKF 7004 CD/P4ADGA, NSK 7004CTRDULP4, NTN 7004UCG/GNP4, RHP 7004CTDULP4 and Koyo 7004C P4 DUL. SNFA VEX 20 /NS 7CE1 shares the 15° angle and envelope. A standard-tolerance 7004-C shares the envelope and angle only. Searchable variants include 2MM9104WIDUL, 2MM-9104-WI-CR-DUL-C1, 2 MM 9104 WI CR DUL and 2MM9104WICRDUL.