6344 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 6344 model number is decoded

In the 6300-series (diameter series 3 of ISO 15) the last two digits encode the bore: 6344 carries bore code 44 = 220 mm. Outside diameter 460 mm and width 88 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 220 mm shaft, typical catalogue practice is a m6 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

• Mount this 220 mm bore bearing by heating the inner ring (induction heater, max 120 °C) — never drive it home through the outer ring or balls, that brinells the raceways.
• The 63xx medium section at 220 mm bore gains dynamic rating through larger rolling elements on a 460 mm OD; the penalty is mass and a lower limiting speed than the 6244 — do not specify it for speed-critical shafts.
• The open 6344 has no lubricant retention: grease escapes and contaminants migrate straight into the 220×460×88 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Storage matters for open bearings: 6344 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.
• Axial location must clamp the ring face, not the seal area: a shoulder or circlip bearing on the seal side of the 88 mm-wide ring of 6344 drags the lip and overheats it.
• Deep-groove ball bearings tolerate only minutes of misalignment; if the 460 mm housing cannot be aligned, switch to a self-aligning type rather than shimming 6344.
• The open 6344 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 220 mm bore places 6344 at the upper end of NSK's single-row deep-groove catalogue for the E1103 Part C extract; this is a heavy-engineering bearing where centrifugal force and cage inertia dominate the design envelope. NSK supplies a machined brass cage (suffix M) and expects oil lubrication with a defined relubrication interval — do not use catalogue grease speed figures for this size without an NSK engineering review.
• NSK rates 6344 at 450 kN dynamic (C) and 520 kN static (C0); this is an extreme-load bearing at the top of the E1103 Part C single-row deep-groove range, where mounting, shaft stiffness and housing alignment dominate the achievable life. Consult NSK engineering for a full application review rather than relying on catalogue L10 alone.
• At 73900 g (73.9 kg), 6344 is a very heavy NSK bearing where handling and mounting method directly affect service life; NSK requires induction heating of the inner ring (max 120 °C), a mechanical puller for removal, and a defined lifting procedure to avoid damaging the cage.
• The 220×460×88 mm envelope of 6344 gives a D/d ratio of 2.09 and 120.0 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 450/520 kN load ratings, mass 73900 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6344 on the 220×460×88 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 6344 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 6344 — a new bearing pressed onto a worn or oval seat reproduces the original failure mode in a fraction of its expected life.
• NSK's VV non-contact seal keeps frictional torque close to the open 6344; in motor duty where heat build-up matters, VV is the usual compromise between debris protection and speed capability.