Fafnir3MM209WIDUHSuper Precision Angular Contact Ball Bearing, Duplex Pair, 45 x 85 x 19 mm, 25° Contact Angle, Heavy Preload, Phenolic Outer-Land-Riding Cage, ABEC 7/9

Product Description

Part identity

A super precision angular contact ball bearing for machine tool spindle positions, supplied as a universally ground duplex pair. Brand: Fafnir (Timken). Manufacturer: Timken. Part Number: 3MM209WI-DUH. Base Number: 3MM209WI. Series: 200WI / 3MM super precision metric. Bearing Type: super precision angular contact ball bearing, spindle type. Condition: New. Unit Quantity: 1 matched duplex pair, 2 bearings.

Dimensions and abutments

Bore d: 45 mm. Outside Diameter D: 85 mm. Width B: 19 mm per bearing. Total Width: 38 mm as a duplex pair. Bore Type: straight. Design Units: Metric. Maximum shaft fillet radius: 1 mm. Shaft backing shoulder diameter: 52.3 mm. Housing backing shoulder diameter: 78.2 mm. Outer ring to-clear radius: 1 mm.

Designation decode

3MM denotes the Fafnir/Timken super precision metric series with a 25° contact angle. 209 places it in the 200WI dimension series with a 45 mm bore. WI is the Fafnir super precision spindle angular contact series. CR, carried on the carton and in Timken’s manufacturing part number, denotes the phenolic outer-land-riding cage, Timken cage designation MBR. DU denotes duplex universally ground rings. H denotes heavy preload. The MM prefix carries ISO P4S rather than P4.

Precision, preload and cage

Precision Class: ISO P4S, ABEC 7/9. Preload: heavy (H). Contact Angle: 25°. Internal Clearance: N/A — a preloaded matched set carries no radial clearance class. Cage Type: machined phenolic, outer-land-riding (CR / Timken MBR). Cage Material: phenolic. Rolling Elements: steel balls. Number Of Rows: 2, one row per bearing, supplied as a pair. Closure Type / Seal Type: open. Heavy preload removes axial play and maximises stiffness and running accuracy, with correspondingly higher internal friction and heat generation than a light or medium preload set. Phenolic is light and self-lubricating, so cage-generated heat is lower than with a steel cage, and outer-land riding lets centrifugal force stabilise the cage at speed.

Contact angle consequence

The 25° contact angle is the deciding specification. Against the 15° execution of the same envelope, 2MM209WI, the steeper angle carries substantially more thrust and gives a stiffer axial response, which suits spindles taking heavy cutting loads or screw-driven axes. The same steeper angle raises ball spin and cage load, so limiting speed is lower and heat generation at a given rpm is higher than the 15° part.

Published ratings and speeds

Dynamic Load Rating C1, 1 million revolutions, duplex set: 9,700 lbf / 43,100 N. C1 ISO dynamic radial rating per row: 8,820 lbf / 39,200 N. Static Load Rating C0: 6,200 lbf / 27,600 N. Limiting Speed, grease: 17,200 rpm. Limiting Speed, oil: 31,600 rpm. Min Temp: -40 °C. Max Temp: 120 °C. Harmonization Code: 8482.10.50. All ratings, speeds and abutment data are Timken’s own published catalogue figures for 3MM209WICRDUH and are specific to the 25° 3MM execution.

Arrangement and configuration

Arrangement / Configuration: duplex universally ground matched pair (DU), mountable back-to-back, face-to-face or tandem. Mounting Arrangement: universal. Each arrangement produces a different consequence: back-to-back gives radial and moment stiffness, face-to-face tolerates a degree of misalignment, and tandem shares thrust in one direction across both rows. Preload is developed by clamping the ground faces solidly together, so the ground faces govern the preload the set delivers.

Cross-references and interchange

Cross-Reference: 7209E-T-P4S-DUH, Timken’s published world part number, where E denotes the 25° contact angle and T the phenolic cage; 7209E-T-P4S; 7209E; 7209 ISO base number for the 45 x 85 x 19 mm envelope; 3MM209WI CR DUH carton form; Fafnir 3MM209WI-DUH legacy brand designation; SKF 7209 ACD/P4A; NSK 7209A5 DUH P4; FAG B7209-E-T-P4S-DUH. 7209-A / 7209A is retained as a search term. Manufacturer Status: Fafnir super precision bearings are branded and supplied by Timken. Functional equivalence within the envelope requires a match on all of contact angle, precision class, cage material and preload class.

Typical applications

Machine tool spindles, CNC milling and turning spindles, grinding spindles, jig borers, precision gearboxes, high-speed rotary tables and screw-driven precision axes. Industry Terms: super precision bearing; spindle bearing; machine tool bearing; angular contact ball bearing; duplex pair; matched set; preloaded bearing; ABEC 7 bearing; phenolic cage bearing; high speed spindle bearing.