Fafnir3MM9111WITULAngular Contact Ball Bearing – 55 mm ID, 90 mm OD, 18 mm Width, Open, 25° Contact Angle, Phenolic Cage, Light Preload, ABEC 7/9 P4S

Product Description

What this part is

Fafnir 3MM9111WICRTUL is a super-precision angular contact ball bearing supplied as a matched triplex set. Bore Diameter: 55 mm. Outside Diameter: 90 mm. Overall Width: 18 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 7011 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.

9111 — the 9100WI dimension series at bore code 11, which is ISO 70-series size 7011 at 55 x 90 x 18 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.

TUL — triplex universal, light preload. Three bearings ground as a matched set with flush faces, so the stack mounts in any combination of back-to-back, face-to-face and tandem.

What these specs mean in practice

Dynamic Load Rating: 35,900 N per bearing. Static Load Rating: 27,200 N per bearing. Both are Timken C1 and C0 values for a single bearing.

Limiting Speed: 14,600 rpm grease; 26,600 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: Light. Light preload keeps running temperature and power draw down while still removing play from the spindle, and it is the usual choice where speed matters more than absolute stiffness.

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.

A triplex stack puts three rows in one bearing position. Two facing one way and one the other gives high stiffness against the dominant thrust direction while still locating the shaft in both, which is the usual arrangement at the front end of a milling spindle.

Mounting data

Bore Diameter: 55 mm. Outside Diameter: 90 mm. Overall Width: 18 mm. Shaft Backing Shoulder Diameter: 62.2 mm (2.450 in). Housing Backing Shoulder Diameter: 83.3 mm (3.280 in). Maximum housing fillet radius that the bearing corners will clear: 1 mm (0.039 in). Item Weight: 1.149 kg (2.52 lb) for the triplex set, 0.383 kg per bearing.

Quantity and configuration

Unit Quantity: 3 Pcs. Mounting Arrangement: Triplex universal (TU). Series: 3MM9100WI. Base Number: 3MM9111WI. GTIN: 087796023420. Harmonization Code: 8482.10.50.

Interchange guidance

The ISO 7011 envelope at 25° and P4-class precision is listed in the cross-reference fields. Match the angle first: a 7011-C at 15° shares this envelope but carries different thrust capacity and a different speed ceiling, so it is a different bearing rather than an equivalent.