6404-NTN bearing: complete specifications & equivalents

Specification table

Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203-3/E (2024)) · extracted 2026-09-25

Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203-3/E (2024)); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.

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 6404-NTN model number is decoded

6404 is supplied open, without shields or seals, so the arrangement around it must supply and retain the lubricant. Within the heavy 64xx section (diameter series 4 of ISO 15), multiplying bore code 04 by five gives the 20 mm bore; the 72 mm outside diameter and 19 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 20 mm shaft under normal load, catalogue practice seats it on a k5 shaft fit with an H7 housing bore — confirm against the actual load direction and magnitude before committing. In the NTN catalogue this open execution carries the bare designation; protected variants are ordered separately with suffixes ZZ (shields), LLB/LLF (non-contact seals), LLH (low-torque contact seal) and LLU (contact seal).

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• A 20 mm shaft for 6404 should be finished to Ra ≤ 1.6 µm with square seating faces; at this bore a scored or oval journal shows up directly as running noise and early raceway damage.
• The 64xx heavy section at 20 mm bore exists for high radial load at moderate rpm; its 72 mm OD and 19 mm width demand a larger housing, and grease life at motor speeds is short — treat it as a low-speed, high-load choice.
• The open 6404-NTN has no lubricant retention: grease escapes and contaminants migrate straight into the 20×72×19 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Storage matters for open bearings: 6404-NTN 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. 6404-NTN-C3. No clearance suffix means normal CN clearance.
• Shaft and housing fillets must clear the bearing chamfer so the 19 mm-wide ring seats square; provide an undercut or withdrawal groove instead of relying on an oversized radius.
• The open 6404 has no integral sealing; in the NTN 2203 catalogue the protected variants carry suffixes ZZ (non-contact steel shields), LLB/LLF (non-contact rubber seals), LLU (contact rubber seals) and LLH (a low-torque contact seal with higher speed capability than LLU). A JR or JRX suffix (printed for some thin-section sizes) denotes a pressed-steel cage, not a seal.
• The 20 mm bore puts 6404 in NTN's light industrial range; the standard pressed-steel cage and CN clearance cover most fractional-horsepower motor and small-pump duty, but for continuous high-speed use specify the LLH low-torque seal (not LLU) and confirm the housing allows the listed limiting speed.
• NTN rates 6404 at 12000 r/min grease limiting speed — this is an electric-motor range; keep the grease fill at 25–35% of the free bearing volume and avoid mixing grease thickener types if regreasing through the housing.
• At 31.5 kN dynamic load rating (C) and 13.9 kN static (C0), 1.09 kN fatigue load limit Cu, 6404 is a medium-load bearing suitable for most electric-motor and pump duty; the C0/C0r ratio matters for preloaded or thrust-loaded arrangements, so confirm the static safety factor with the NTN catalogue.
• At 400 g, 6404 requires a soft-jaw vise or arbor press for mounting — never hammer it onto the shaft, and support the opposite ring to avoid brinelling the raceways.
• The 20×72×19 mm envelope of 6404 gives a D/d ratio of 3.60 and 26.0 mm radial section height — a heavy 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 31.5/13.9 kN load ratings, 1.09 kN fatigue load limit Cu NTN lists the grease limiting speed at 12000 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 400 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6404 on the 20×72×19 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 6404 in a rated drive.
• Two NTN bearings of the same designation from different production lots can carry minor internal-geometry revisions; for paired or preloaded arrangements on one shaft, order a single lot through the NTN distributor.
• Order the C3 internal-clearance version (6404 with C3 after the seal code) when the shaft fit is tight or the shaft-to-housing temperature gradient exceeds roughly 10 °C — the residual clearance after mounting, not the catalogue CN figure, decides service life.