Fafnir3MM307WIDUHSuper-Precision Angular Contact Ball Bearing Pair – 35 mm Bore, 80 mm OD, 21 mm Width, 25°, Heavy Preload

Product Description

What this part is

Fafnir 3MM307WICRDUH, a super-precision angular contact ball bearing supplied as a universally ground duplex pair. Bore Diameter: 35 mm. Outside Diameter: 80 mm. Overall Width: 21 mm per bearing. Total Width: 42 mm mounted as a pair. Contact Angle: 25°. 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: Heavy. Series: 300WI. Base Number: 3MM307WI. Lubricant: factory grease as shipped. GTIN: 087796209442.

Decoding the designation

3MM — Fafnir super-precision spindle range at a 25° contact angle, ground to ABEC 7/9 (P4S) tolerances.

307 — 300 heavy dimension series, bore code 07: a 35 mm bore in an 80 mm outside diameter.

WI — low shoulder on both rings.

CR — phenolic cage.

DUH — duplex pair, universally ground, heavy 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: 44,500 N per bearing. Static Load Rating: 24,700 N per bearing. Limiting Speed: 18,800 rpm grease; 34,600 rpm oil. Item Weight: 0.886 kg (1.96 lb) for the pair. Internal Clearance: N/A — a preloaded set is clamped to a defined stiffness rather than run to a clearance. Heavy preload is the stiffest of the three Fafnir grades and holds axial position hardest under reversing thrust. The 25° contact angle carries more thrust than the 15° execution on the same envelope and turns slower for it.

Mounting data

Shaft Backing Shoulder Diameter: 43.2 mm. Housing Backing Shoulder Diameter: 72.1 mm. Maximum Housing Fillet Radius: 1.5 mm (0.059 in) — the largest housing corner radius the bearing corners will clear.

Quantity and configuration

Unit Quantity: 2 Pcs. One universally ground duplex pair. The 21 mm figure is the width of a single bearing; the pair occupies 42 mm of shaft length when clamped together.

Interchange guidance

Direct super-precision equivalents on the 7307 envelope at 25° with heavy preload: FAG B7307-E-T-P4S-UL, SKF 7307 ACD/P4ADGC, NSK 7307A5TRDUHP4, NTN 7307UAD/GNP4, RHP 7307ETDUHP4 and Koyo 7307A5 P4 DUH. A standard-tolerance 7307-A shares the envelope and angle only. Searchable variants include 3MM307WIDUH, 3MM-307-WI-DUH, 3 MM 307 WI CR DUH, 3MM307WICRDUH and 7307E-T-DUH-P4.