6004-NSK bearing: complete specifications & equivalents

Specification table

Source: catalog reference (NSK Rolling Bearings E1103 Part C) · extracted 2026-09-24

Cross references & equivalents

Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.

How the 6004-NSK model number is decoded

In the 6000-series (diameter series 0 of ISO 15) the last two digits encode the bore: 6004 carries bore code 04 = 20 mm. Outside diameter 42 mm and width 12 mm come from the ISO 15 boundary-dimensions general plan. With no seal suffix the bearing is open: no shields or seals are fitted and lubrication is supplied by the application. For normal-load mounting with a rotating inner ring on a 20 mm shaft, typical catalogue practice is a k5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. In the NSK catalogue this open execution carries the bare designation; protected variants are ordered separately with suffixes ZZ (steel shields), VV (non-contact rubber seals) and DDU (contact rubber seals).

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Sizes around 20 mm bore are normally pressed on cold with a sleeve against the inner-ring face; the press force must never route through the outer ring or the balls of 6004-NSK.
• Choosing the 60xx extra-light section saves radial space at 20 mm bore, but the trade-off is rating: if the drive sees shock or frequent start-stop cycles, re-check the L10 life against a 6204 before committing to the smaller envelope.
• The open 6004-NSK has no lubricant retention: grease escapes and contaminants migrate straight into the 20×42×12 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Storage matters for open bearings: 6004-NSK leaves the factory with rust preventive only, so clean it and apply the service grease at assembly even if the rings look oily from the wrapper.
• Suffixes stack in a defined order — clearance follows the seal code, e.g. 6004-NSK-C3. No clearance suffix means normal CN clearance.
• A 20 mm bore listing showing the right d/D/B but no standard or precision-class reference may be a loose-tolerance import; measure bore/OD spread before fitting it to a machined shaft.
• The open 6004 has no integral sealing; in the NSK E1103 catalogue the protected variants carry suffixes ZZ (non-contact steel shields), VV (non-contact rubber seals) and DDU (contact rubber seals). NSK does not offer a low-torque contact seal equivalent to NTN's LLH in this catalogue — for high-speed sealed duty specify the VV non-contact seal and an external housing labyrinth.
• The 20 mm bore puts 6004 in NSK's light industrial range; the standard pressed-steel cage and CN clearance cover most fractional-horsepower motor and small-pump duty. NSK's VV non-contact seal is the high-speed choice here — DDU contact seal costs roughly 30–40% of the open-bearing speed ceiling.
• NSK rates 6004 at 10.3 kN dynamic (C) and 5 kN static (C0); this light-to-medium rating suits fractional-horsepower drives and instruments — for conveying or gearbox duty with shock loads, verify the equivalent dynamic load stays well below C.
• At 68 g, 6004 is light enough for hand assembly but should be pressed on with a fitting sleeve against the inner ring; do not strike the outer ring or cage with a hammer.
• The 20×42×12 mm envelope of 6004 gives a D/d ratio of 2.10 and 11.0 mm radial section height — a heavy NSK section built for high-load, lower-speed duty; specifying it in a high-rpm motor generates excess heat and shortens grease life, so prefer a 62/63-series there.
• The 10.3/5 kN load ratings, mass 68 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6004 on the 20×42×12 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 6004 in a rated drive. NSK does not tabulate reference or limiting speeds in the E1103 Part C dimension tables used for this page — consult NSK's separate speed-rating tables before high-speed service.
• When replacing a failed unit, inspect the shaft and housing seats before fitting the new 6004 — a new bearing pressed onto a worn or oval seat reproduces the original failure mode in a fraction of its expected life.
• Keep NSK bearings in the original packaging until fitting: the wrapper carries the production lot, and the unopened shelf life of greased sealed units is typically quoted at three to five years in dry, vibration-free storage.