Fafnir2MM9124WIQULAngular Contact Ball Bearing – Straight Bore, 120 mm ID, 180 mm OD, 28 mm Width, Open, 15° Contact Angle, Phenolic Outer Land Riding Cage, Light Preload, ABEC 7/9 P4S

Product Description

What this part is

Fafnir 2MM9124WICRQUL is a super-precision angular contact ball bearing supplied as a matched quad set. Bore Diameter: 120 mm. Outside Diameter: 180 mm. Overall Width: 28 mm. Contact Angle: 15°. Bore Type: Straight. Closure Type: Open. Rolling Elements: Ball. Number Of Rows: 1 per bearing. Cage Material: Phenolic. Cage Type: Outer-ring land riding. Bearing Material: Bearing steel. The envelope is the ISO 7024 size, and Timken’s own world part number for it is 7024C-T-P4S.

Decoding the designation

2MM — Timken Fafnir super-precision at a 15° contact angle. The 2 prefix carries the angle; MM is the P4S precision grade, which Timken’s own product data states as ISO P4S (ABEC 7/9).

9124 — the 9100WI dimension series at bore code 24, which is ISO 70-series size 7024 at 120 x 180 x 28 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, riding on the outer-ring land. Timken publishes it as a phenolic outer land riding cage for this bearing, and it is the T in the ISO world number 7024C-T-P4S.

QUL — quad universal, light preload. Four 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: 111,200 N per bearing. Static Load Rating: 108,500 N per bearing. Both are Timken C1 and C0 values for a single bearing. Timken also publishes the ISO 281 equivalent at 101,000 N per row; the difference is the one-million-revolution C1 convention against the ISO basis, not a set-versus-single distinction.

Limiting Speed: 6,900 rpm grease; 13,800 rpm oil. Lubricant: Grease or oil.

Contact Angle: 15°. A shallow angle favours speed and radial stiffness over axial capacity, which is the trade a machine tool spindle wants.

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.

Cage Type: Outer-ring land riding. The cage is piloted on the outer ring land rather than on the balls, which steadies it at speed and keeps pocket wear down.

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 quad set puts four rows in one bearing position. Splitting them two and two gives balanced thrust capacity in both directions; splitting them three and one biases stiffness toward the dominant cutting direction.

Mounting data

Bore Diameter: 120 mm. Outside Diameter: 180 mm. Overall Width: 28 mm. Shaft Backing Shoulder Diameter: 132.5 mm (5.220 in). Housing Backing Shoulder Diameter: 168.3 mm (6.630 in). Maximum housing fillet radius that the bearing corners will clear: 2 mm (0.079 in). Maximum shaft fillet radius that the bearing corners will clear: 2.0 mm (0.079 in). Item Weight: 8.72 kg (19.24 lb) for the quad set, 2.18 kg per bearing.

Quantity and configuration

Unit Quantity: 4 Pcs. Mounting Arrangement: Quad universal (QU). Series: 2MM9100WI. Base Number: 2MM9124WI. GTIN: 087796229822. Harmonization Code: 8482.10.50.

Interchange guidance

The ISO 7024 envelope at 15° and P4-class precision is made by every major super-precision manufacturer; the cross-reference fields list them, most as universal singles to be ordered four at a time. Match preload as well as angle: this set is ground to light preload, and a medium or heavy execution of the same designation carries a different Timken UPC.