The dynamic load rating of 10.4 kN characterises this bearing. The static load rating is 5.05 kN. The limiting speed is 21000 rpm. In the open form the rolling chamber lies exposed — lubricant supply, heat dissipation and any assessment of the grease condition are handled by the surrounding design rather than by a seal supplied with the bearing.
In a deep groove ball bearing a single row of balls runs in one deep raceway groove in each of the inner and outer ring, the curvature radius of which is only slightly larger than the ball radius. Both consequences follow from this close conformity: a small contact area that widens into an ellipse under load, with correspondingly low rolling friction, and the ability to transmit axial force in both directions through the groove shoulders.
That axial capability is tied to the contact angle which establishes itself under axial load — it therefore depends on the clearance remaining in the mounted state and is not a fixed property of the size. The bearing is non-separable: both rings and the ball set form one unit, which is why the mounting force must always be applied through whichever ring receives the interference fit, and never through the rolling contact.
The open form brings no sealing element of its own; sealing, initial filling and relubrication rest with the design, which in exchange is free to use oil, oil-mist or circulating lubrication and to carry heat away with the lubricant. Through-hardened standard bearing steel provides hardness, dimensional accuracy and fatigue strength across the usual operating temperature range; whether a position may be run above it is to be taken from the designation and the dimensional stabilisation data.
The normal radial clearance is matched to one interference-fitted ring and a moderate temperature difference between inner and outer ring; what governs is always the residual clearance in the mounted, warm running state, not the clearance as delivered. Because no sealing element isolates the bearing position, the cleanliness and lubricant supply of the surroundings decide the achievable service life in practice more often than material fatigue does.
ManufacturerNTN
Bearing typeDeep-groove ball bearings
Bore d20 mm
Outer Ø D42 mm
Width B12 mm
Dyn. load C10.4 kN
Stat. load C₀5.05 kN
Fatigue limit Pu0.355 kN
Limiting speed21,000 min⁻¹
Reference speed21,000 min⁻¹
Weight0.072 kg
Sealsnone (open bearing)
Clearancenormal radial internal clearance
Cagepressed steel cage
Materialstandard bearing steel
Tolerancetolerance class P0/PN (ABEC 1)
Bore typecylindrical bore
€2.86/ pc
incl. VAT, plus shipping · price drops with quantity
In stock
Typically ready to ship in 1–2 days
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QtyUnit priceDisc.
1 – 4€2.86—
5 – 9€2.77−3 %
10 – 24€2.71−5 %
25 – 49€2.63−8 %
50 – 99€2.57−10 %
4 more for −3% volume discount
From 100 pcs: price and lead time on request – subject to review.
Total (1 pc)€2.86
NTN 6004 Kugellager (20x42x12)
— 20 x 42 x 12 mm
Response within 4 business hours
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✓Purchase on invoice – first order paid before dispatch, then 14-day terms for approved business customers
Same dimensions means the same bearing type and matching main dimensions (d × D × B). Sealing, cage, internal clearance and execution (e.g. material, precision, grease fill) are encoded in the suffix and may differ — please check before ordering. Equivalent additionally means the same sealing, internal clearance and tolerance class; the cage and other suffix features (e.g. lubrication groove) may differ.
