FafnirSuper Precision Angular Contact Ball Bearing – Straight Bore, 100 mm ID, 150 mm OD, 24 mm Width, Open, 25° Contact Angle, Phenolic Cage, Universal Heavy Preload, ABEC 7/9 P4S

Product Description

What this part is

Fafnir 3MM9120WICRDUH is a super-precision angular contact ball bearing supplied as a matched duplex pair. Bore Diameter: 100 mm. Outside Diameter: 150 mm. Overall Width: 24 mm. Contact Angle: 25°. Bore Type: Straight. Closure Type: Open. Rolling Elements: Ball. Number Of Rows: 1 per bearing. Cage Material: Phenolic. Bearing Material: Bearing steel. The envelope is the ISO 7020 size.

Decoding the designation

3MM — Timken Fafnir super-precision at a 25° contact angle. The 3 prefix carries the angle; MM is the P4S precision grade, which holds ABEC 9 / ISO P2 running accuracy on an ABEC 7 / ISO P4 body.

9120 — the 9100WI dimension series at bore code 20, which is ISO 70-series size 7020 at 100 x 150 x 24 mm.

WI — Timken’s standard angular contact construction: full shoulders on both sides of the inner ring and a low shoulder on the outer ring.

CR — phenolic composition cage, Timken’s standard cage for super-precision spindle bearings.

DUH — duplex universal, heavy preload. Two bearings ground as a matched set with flush faces, so the pair mounts back to back, face to face or in tandem.

What these specs mean in practice

Dynamic Load Rating: 79,200 N per bearing. Static Load Rating: 73,400 N per bearing. Both are Timken C1 and C0 values for a single bearing.

Limiting Speed: 8,300 rpm grease; 15,000 rpm oil. Lubricant: Grease or oil.

Contact Angle: 25°. The steeper 25° angle carries substantially more thrust than the 15° execution of the same size and gives higher axial stiffness, in exchange for a lower speed ceiling.

Preload: Heavy. Heavy preload raises spindle stiffness and holds the ball complement in controlled contact through load reversals, at the cost of running temperature.

Precision Class: ABEC 7/9 / P4S. Super-precision grinding holds bore, outside diameter and raceway running accuracy far tighter than a standard-class bearing, which is what keeps spindle runout and running vibration low at speed.

Mounting data

Bore Diameter: 100 mm. Outside Diameter: 150 mm. Overall Width: 24 mm. Shaft Backing Shoulder Diameter: 109.9 mm (4.330 in). Housing Backing Shoulder Diameter: 140.8 mm (5.550 in). Maximum housing fillet radius that the bearing corners will clear: 1.5 mm (0.059 in). Item Weight: 2.598 kg (5.72 lb) for the matched pair, 1.299 kg (2.86 lb) per bearing.

Quantity and configuration

Unit Quantity: 2 Pcs. Mounting Arrangement: Duplex universal (DU). Series: 3MM9100WI. Base Number: 3MM9120WI. GTIN: 087796073074. Harmonization Code: 8482.10.50.

Interchange guidance

The closest parts at 25° and P4-class precision are NSK 7020A5TRDUHP4 and RHP 7020X3TDUHP4, both heavy preload duplex sets. FAG B7020-E-T-P4S-UL is light preload, SKF 7020 ACD/P4A takes its preload from the DG suffix, and the single Fafnir 3MM9120WICRSUH is not a matched pair. A 7020-C at 15° shares this size but carries different thrust capacity and a different speed ceiling, so it is a different bearing.