Fafnir2MM210WIDUMSuper-Precision Angular Contact Ball Bearing Pair – 50 mm Bore, 90 mm OD, 20 mm Width, 25°, Medium Preload

Product Description

What this part is

Fafnir 3MM210WICRDUM, a super-precision angular contact ball bearing supplied as a universally ground duplex pair. Bore Diameter: 50 mm. Outside Diameter: 90 mm. Overall Width: 20 mm per bearing. Total Width: 40 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: Medium. Series: 200WI. Base Number: 3MM210WI. GTIN: 087796070561.

Decoding the designation

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

210 — 200 medium dimension series, bore code 10, which maps to the ISO 7210 envelope: 50 mm bore, 90 mm outside diameter, 20 mm width.

WI — low shoulder on both rings.

CR — phenolic cage.

DUM — duplex pair, universally ground, medium 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: 45,200 N per bearing. Static Load Rating: 30,200 N per bearing. Limiting Speed: 15,800 rpm grease; 28,800 rpm oil. Item Weight: 0.914 kg (2.02 lb) for the pair. Internal Clearance: N/A — a preloaded set is clamped to a defined stiffness rather than run to a clearance. The 25° contact angle carries more thrust and locates the shaft more firmly than a 15° execution on the same envelope, and turns slower for it. Medium preload sits between light and heavy: more stiffness than light, less running heat than heavy.

Mounting data

Shaft Backing Shoulder Diameter: 57.4 mm. Housing Backing Shoulder Diameter: 83.3 mm. Maximum Housing Fillet Radius: 1 mm (0.039 in) — the largest housing corner radius the bearing corners will clear.

Quantity and configuration

Unit Quantity: 2 Pcs. One universally ground duplex pair. The 20 mm figure is the width of a single bearing; the pair occupies 40 mm of shaft length when clamped together.

Interchange guidance

Direct super-precision equivalents on the 7210 envelope at 25° with medium preload: FAG B7210-E-T-P4S-UL, SKF 7210 ACD/P4ADGB, NSK 7210A5TRDUMP4, NTN 7210UAD/GNP4, RHP 7210ETDUMP4 and Koyo 7210A5 P4 DUM. SNR 7210HG1DUJ84 is the equivalent French execution. A standard-tolerance 7210A shares the envelope and angle only. Searchable variants include 3MM210WIDUM, 2MM-210-WI-DUM, 3MM-210-WI-CR-DUM, 3 MM 210 WI CR DUM, 3MM210WICRDUM and 7210A-T-DUM-P4.