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Deep Groove Ball Bearings: The Industry Default and When to Reach for Something Else
If you pulled a bearing off general industrial equipment at random, there’s a good chance
Availability:
2 in stock
Super-precision angular contact ball bearing, 45 x 100 x 25 mm, 25° contact angle, phenolic cage, matched duplex pair at light preload. 2 Pcs.
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$83.33
2 in stock
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| MFR / Brand | Fafnir |
|---|---|
| MPN | 3MM309WI DUL |
| Model | 3 MM 309 WI CR DUL / 7309 E T DUL P4 7309A 7309A5 7309ACD |
| Bearing Type | Angular Contact Ball Bearing, Open |
| ID | 45 mm |
| OD | 100 mm |
| Width | 25 mm |
| Material | Bearing Steel |
|---|---|
| Series | 7300 |
| Lubricant | Oil |
| Base Number | 7309 |
| Industry Terms | Spindle bearing; super precision bearing; machine tool bearing; duplex pair; ABEC 7 angular contact |
| Common Misspellings | Fafner; Faffnir; Fanfir; 3MM309W1; 3MM309WIDUL |
| Application Types | Machine tool spindles; grinding spindles; high-speed gearboxes; precision rotary tables |
| Bore Shaft Size | 45 mm (1.7717 in) |
| Mpn Variants | 3MM309WI-DUL; 3MM309WICRDUL; 3MM-309-WI-CR-DUL; 3MM309WI; 3MM 309 WI CR DUL |
| Manufacturer Status | Fafnir is the Timken super-precision line |
| Rolling Elements | Ball |
| Number Of Rows | 1 per bearing |
| Bore Type | Straight |
| Snap Ring Included | Without Snap Ring |
| Harmonization Code | 8482.10.50.28 |
| Contact Angle | 25° |
| Part Number | 3MM309WI-CR-DUL |
A Fafnir 3MM309WI-CR-DUL super-precision angular contact ball bearing, 45 mm bore by 100 mm outside diameter by 25 mm wide, supplied as a universally ground duplex pair at light preload. Fafnir is Timken’s super-precision spindle bearing line and WI is its single-row angular contact spindle family. The ISO equivalent envelope is the 7309 size.
The leading 3 in 3MM gives a 25° contact angle. The MM prefix denotes P4S precision, ABEC 7 on dimensional tolerances with ABEC 9 running accuracy. The size block 309 places the bearing in the ISO 73 medium dimension series with a bore code of 09 for 45 mm, which is why the outside diameter and width are heavier than a 7209 of the same bore. CR is a phenolic cage riding on the outer ring land and DUL a duplex universally ground pair at light preload.
The 73 medium series puts more material and larger balls into the same bore than the 72 series, which raises both radial and axial capacity at the cost of speed. The 25° angle biases that capacity toward thrust. Light preload is the setting chosen where speed and heat generation matter more than axial stiffness, and it is the usual choice for the drive end of a spindle running long cycles.
2 Pcs, one matched duplex pair. Universally ground rings allow back-to-back, face-to-face or tandem mounting, with the preload established by the ground ring offsets.
The marked faces go together in the chosen arrangement and both rings are clamped fully against their shoulders, which is what converts the ground offset into preload. Fits on a P4S bearing are held far tighter than on general-purpose stock, and the bearing is fitted clean and lubricated to its final grease or oil specification.
An NSK 7309A5 or an SKF 7309 ACD/P4A in an equivalent light-preload duplex pair is the same specification. A 7309 in the 15° C angle or the 40° B angle is a related size in the same envelope rather than a substitution. A 7209 shares the 45 mm bore but is a lighter series with a smaller outside diameter and different capacity.
$152.21
35 in stock
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