Fafnir3MM9121WICRSULAngular Contact Ball Bearing – 105 mm ID, 160 mm OD, 26 mm Width, 25° Contact Angle, Light Preload, Universally Ground, ABEC 7/9

Product Description

What this part is

Fafnir 3MM9121WI-CR-SUL super-precision angular contact ball bearing, 9100WI spindle series, 105 x 160 x 26 mm. Bore Diameter: 105 mm. Outside Diameter: 160 mm. Overall Width: 26 mm. Contact Angle: 25°. Precision Class: ABEC 7/9 / P4S. Cage Material: Phenolic. Rolling Elements: Ball. Bearing Material: Chrome steel. Bore Type: Straight. Closure Type: Open. Number Of Rows: 1. Item Weight: 1.617 kg (3.57 lb). GTIN: 087796340565.

Decoding the designation

3 — 25° contact angle.

MM — Fafnir super-precision spindle execution, ISO P4S tolerance class.

9121 — 9100WI series, which maps to the ISO 70xx dimension series; bore code 21 gives a 105 mm bore and the ISO equivalent 7021.

WI — low shoulder on both rings, the spindle bearing form.

CR — phenolic cage.

SUL — single universally ground bearing, light preload.

What these specs mean in practice

Dynamic Load Rating: 92,100 N. Static Load Rating: 84,500 N. Limiting Speed: 7,900 rpm grease; 14,200 rpm oil. Lubricant: grease or oil.

A 25° contact angle carries more thrust and less speed than a 15° execution of the same size. Light preload keeps running heat and friction torque down while still removing internal play. Preload and internal clearance are mutually exclusive, so Internal Clearance: N/A.

Universal grinding lets this bearing be stacked with others of the same number in back-to-back, face-to-face or tandem sets, with the light preload arriving automatically when the faces are clamped together.

Mounting data

Shaft Backing Shoulder Diameter: 115.7 mm (4.560 in). Housing Backing Shoulder Diameter: 150 mm (5.910 in). Maximum housing fillet radius that the bearing corners will clear: 2 mm (0.079 in).

Quantity and configuration

Unit Quantity: 1 Pc. Mounting Arrangement: single universally ground, light preload.

Interchange guidance

Timken 7021AC-T-P4S-SUL, SKF 7021 ACD/P4A, FAG B7021-E-T-P4S-UL and NSK 7021A5TRSULP4 share the 105 x 160 x 26 mm envelope, the 25° angle, P4S tolerance and universal grinding at light preload. A standard-precision 7021AC matches the envelope and the angle at a looser tolerance class. Searchable forms of this number include 3MM9121WI, 3MM-9121-WI-CR-SUL and 7021.