6344-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 6344-NTN model number is decoded

6344 is supplied open, without shields or seals, so the arrangement around it must supply and retain the lubricant. Within the medium 63xx section (diameter series 3 of ISO 15), multiplying bore code 44 by five gives the 220 mm bore; the 460 mm outside diameter and 88 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 220 mm shaft under normal load, catalogue practice seats it on a m6 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

• 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 series gains rating at 220 mm bore through a 460 mm OD and 88 mm width; the heavier rolling elements also trade away some speed versus a 6244.
• The open 6344-NTN 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-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.
• Vibration during standstill brinells the raceways of a 220 mm bearing at ball spacing; if the machine sits idle next to running equipment, turn the shaft over periodically or isolate the arrangement.
• 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-NTN.
• The open 6344 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 220 mm bore places 6344 in NTN's upper large-size range; centrifugal force at this diameter sharply caps the grease limiting speed, so NTN usually supplies a machined brass cage (suffix M) and expects oil lubrication for continuous duty. Confirm relubrication interval and cage material with the NTN distributor.
• NTN lists the grease limiting speed at 1400 r/min for 6344; this is a large-section size where the pressed-steel cage is speed-limited — NTN recommends the machined brass cage (suffix M) and oil lubrication for any continuous operation above this figure.
• At 455 kN dynamic load rating (C) and 520 kN static (C0), 22 kN fatigue load limit Cu, 6344 is a very-heavy-load bearing for large industrial gearboxes and steel-mill equipment; NTN supplies a machined brass cage (suffix M) and expects an application review, because catalogue L10 life alone does not capture the shock and misalignment loads at this rating.
• At 60800 g (60.8 kg), 6344 is an extremely heavy bearing at the top of the single-row deep-groove range; NTN mandates induction heating (max 120 °C), a dedicated lifting fixture, and a machined brass cage (suffix M). Consult NTN engineering for the mounting and handling procedure before installation.
• 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 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 455/520 kN load ratings, 22 kN fatigue load limit Cu NTN lists the grease limiting speed at 1400 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 60800 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E 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.
• Standard catalogue stock of 6344 is the general-purpose execution; for low-noise motor duty NTN offers low-torque seal and special-grease variants in this size class, which are separate order numbers.
• Order the C3 internal-clearance version (6344 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.