GMNS6010ETAA7UMSuper Precision Angular Contact Spindle Bearing 50 x 80 x 16 mm 25° ABEC 7 Medium Preload

Product Description

What this part is

A single-row super-precision angular contact spindle ball bearing from the GMN S series, 50 mm bore, 80 mm outside diameter, 16 mm width. The rings are ground to ABEC 7 accuracy and universally ground, so any two pieces of this designation clamp together in a back-to-back, face-to-face or tandem stack and reach the specified medium preload without shimming.

Decoding the order code

S is the GMN S-series spindle bearing execution, the steel high-load line. 6010 is the GMN size code for the 50 mm bore, 80 mm outside diameter, 16 mm wide envelope, the same envelope as an ISO 7010. E is a 25 degree contact angle. TA is the GMN cage code. A7 (ABEC7) is ABEC 7 tolerances, equivalent to ISO class 4 / P4. U is universally ground, one piece. M is the medium preload grade.

What these specs mean in practice

GMN offers this series in 15° and 25° contact angles, and the choice sets the balance between thrust and speed. At 25° the ball load line stands further from the radial plane, which raises axial load capacity and axial stiffness — the property that holds a spindle’s face position under cutting thrust. The price is speed and heat: a steeper angle increases the centrifugal and gyroscopic loading on the ball set at a given rotational speed, so the 25° variant runs to a lower speed ceiling than the 15° one in the same envelope. GMN publishes a reference speed factor of n × dm = 1,700,000 mm/min for the standard S series.

Medium preload sits in the middle of the stiffness-versus-heat trade. Preload removes internal clearance, fixes the contact angle and gives repeatable axial location and low runout; the friction it generates warms the rings, and that warming shifts the preload as the spindle reaches temperature. A medium grade delivers noticeably more static and dynamic stiffness than a light grade while staying below the thermal demands of a heavy one, which is why it is the usual choice for general machining-spindle and grinding-head duty rather than for the fastest lightly loaded work.

ABEC 7 accuracy is what allows the bearing into a ground spindle stack: bore, outside diameter, width and ring runout are held to single-digit micron limits, so the ball path stays concentric with the spindle axis and the tool tip does not describe a circle. Universal grinding then converts those tolerances into the preload directly, since the ground face relief is what the clamping force works against.

Published specifications

Bore: 50 mm (1.9685 in). Outside Diameter: 80 mm (3.1496 in). Width: 16 mm (0.6299 in). Rows: 1. Contact Angle: 25°. Preload Grade: Medium (M). Matching: universally ground single (U). Precision: ABEC 7 (ISO class 4 / P4). Closure: open, both faces. Dynamic Load Rating: 26.5 kN (5,957 lbf). Static Load Rating: 23.1 kN (5,193 lbf). Limiting Speed: 22,000 rpm. Reference speed factor, S series: n × dm = 1,700,000 mm/min.

Quantity and configuration

Single bearing, universally ground. 1 Pc.

Interchange guidance

The Fafnir / Timken 3MM9110WI CR SUM is the same specification in another maker’s scheme — 3MM is 25°, SUM is a universally ground single at medium preload — with Fafnir’s MM prefix carrying P4S accuracy rather than P4. 7010ACD is the ISO and SKF base designation for a 25° bearing in this envelope. Same-envelope bearings with a different contact angle, preload grade or accuracy class — the 15° S 6010 C TA execution, the light and heavy preload grades, and duplex-ground sets — are related sizes rather than equivalents.