FafnirPMM210KSMBRSpindle Deep Groove Ball Bearing – 50 mm Bore, 90 mm Outside Diameter, 20 mm Width, Open, Machined Bronze Cage, ABEC 7 / P4S

Product Description

What this part is

Fafnir PMM210KSMBR single-row spindle deep groove ball bearing, 200K series, made in the USA. Bore Diameter: 50 mm. Outside Diameter: 90 mm. Overall Width: 20 mm. Bore Type: Straight. Closure Type: Open. Rolling Elements: Ball. Number Of Rows: 1. Cage Material: Bronze. Cage Type: Machined. Bearing Material: Chrome steel. Internal Clearance: CN. Precision Class: ABEC 7 / P4S. Series: 200. Base Number: 210K.

Decoding the designation

MM — Fafnir super-precision build. Precision Class: ISO P4S, ABEC 7/9 running accuracy.

210 — 200 series, bore code 10, giving a 50 mm bore on the 90 mm outside diameter of the 6210 envelope.

K — spindle deep groove execution: a Conrad-type deep groove raceway built to spindle tolerances, so it carries no contact angle.

MBR — machined bronze cage. Bronze runs cooler under marginal lubrication than a polymer cage and holds its form at temperature.

What these specs mean in practice

Dynamic Load Rating: 38,900 N at one million revolutions, and 35,400 N on the ISO basis. Static Load Rating: 23,100 N. Precision Class: ABEC 7 / P4S, which is the tolerance grade a grinding or milling spindle needs to hold runout at speed. Internal Clearance: CN, the standard clearance group. A deep groove geometry takes radial load and axial load from either direction in the same bearing, so a spindle can be located axially on one of these.

Mounting data

Maximum shaft fillet radius cleared by the bearing corner: 1 mm. Shaft backing shoulder diameter: 57.4 mm. Housing backing shoulder diameter: 83.3 mm. Outer ring “to clear” radius: 1 mm. Lubricant: grease or oil.

Quantity and configuration

Unit Quantity: 1 Pc. Single bearing, open on both faces.

Interchange guidance

The envelope is the standard 6210 boundary at 50 x 90 x 20 mm, so a standard-class 6210 from SKF, FAG, NSK, NTN, Koyo, MRC or Nachi fits the same seat. Those are commercial Conrad-type bearings at normal tolerance; this piece is the P4S spindle execution with a machined bronze cage. The Timken MM210K is the same size and class with a phenolic cage. Searchable forms of the number: PMM210KSMBR, P-MM-210-K-SMBR, MM210K, 210K and 6210-P4.