Fafnir2MM312WICRDULSuper-Precision Angular Contact Ball Bearing Duplex Pair – Straight Bore, 60 mm ID, 130 mm OD, 31 mm Width, Open, 15° Contact Angle, ABEC 7/9, Light Preload, 2 Pcs

Product Description

What this part is

Fafnir 2MM312WI-DUL super-precision angular contact ball bearing set, ISO 7312 envelope, 60 mm bore x 130 mm outside diameter x 31 mm width per bearing. Bore: 60 mm. Outside Diameter: 130 mm (5.118 in). Overall Width: 31 mm (1.221 in). Total Width: 62 mm across the pair. Bore Type: Straight. Number Of Rows: 1 per bearing. Rolling Elements: Steel balls. Closure Type: Open. Contact Angle: 15°. Precision Class: ABEC 7/9 (ISO P4S). Preload: Light. Cage Material: Machined laminated phenolic. Cage Type: Outer-ring land-riding, machined. Design Units: Metric. Material: Chrome bearing steel. Country of Origin: United States.

Decoding the designation

2MM: 15° contact angle in Timken’s Fafnir super-precision scheme, and the MM prefix carries ISO tolerance class P4S, equal to ABEC 7/9. 312: the 300WI heavy series, which maps to ISO 7312. WI: super-precision spindle execution. CR: machined phenolic cage riding on the outer-ring land. DU: universally faced duplex pair. L: light preload. Timken’s own world part number for this set is 7312C-T-P4S-DUL. Searchable variants: 2MM-312-WI-CR-DUL, 2MM312WI DUL, 2MM312WICRDUL, 7312C, 7312C-T-P4-DUL.

What these specs mean in practice

Dynamic Radial Load Rating, set: 103,100 N (23,200 lbf). Dynamic Radial Load Rating per row, ISO C1: 93,700 N (21,100 lbf). Static Radial Load Rating: 63,500 N (14,300 lbf). Limiting Speed, grease lubrication: 11,400 rpm. Limiting Speed, oil lubrication: 22,800 rpm. The 300WI heavy series carries the largest ball complement of the super-precision sections at a given bore, which is why a 60 mm bore reaches a six-figure newton dynamic rating here. A 15° contact angle favours speed and radial stiffness over thrust capacity. The machined phenolic cage rides on the outer-ring land, so cage guidance comes from the stationary ring and stays stable as speed rises. Lubricant: grease or oil. Maximum Operating Temperature: 120 °C. Minimum Operating Temperature: -30 °C.

Quantity and configuration

Unit Quantity: 2 Pcs. Rows Per Set: Duplex. A matched pair with universally ground faces, so the two bearings mount back-to-back, face-to-face or in tandem and reach light preload when clamped. Internal Clearance: N/A — face grinding sets the axial position on a universally faced preloaded set, in place of a radial clearance class.

Fitting notes

Shaft Backing Shoulder Diameter: 72.6 mm (2.860 in). Housing Backing Shoulder Diameter: 117.9 mm (4.640 in). Maximum Shaft Fillet Radius: 2 mm (0.079 in). Outer Ring To-Clear Radius: 2 mm (0.079 in).

Interchange guidance

Same-specification equivalents: Timken world part number 7312C-T-P4S-DUL, NSK 7312CTRDULP4, SKF 7312 CD/P4ADGA, FAG B7312-C-T-P4S-UL. A 3MM312WI set shares the 60 x 130 x 31 mm envelope at a 25° contact angle, which is a related size rather than a substitution.