6328-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 6328-NTN model number is decoded

In the 6300-series (diameter series 3 of ISO 15) the last two digits encode the bore: 6328 carries bore code 28 = 140 mm. Outside diameter 300 mm and width 62 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 140 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 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

• Large bores like the 140 mm of 6328-NTN demand clean, burr-free seats; one raised burr under a ring this size cocks the bearing and concentrates load at the raceway edge, cutting life drastically.
• The 63xx medium section at 140 mm bore gains dynamic rating through larger rolling elements on a 300 mm OD; the penalty is mass and a lower limiting speed than the 6228 — do not specify it for speed-critical shafts.
• The open 6328-NTN has no lubricant retention: grease escapes and contaminants migrate straight into the 140×300×62 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Open bearings tolerate the highest speeds in the 6300-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 6328 units.
• Do not quieten a noisy bearing by preloading it: the 6300-series is a deep-groove design, not angular-contact; axial preload raises temperature and shortens grease life.
• The housing bore for the 300 mm OD should be round within IT7; an oval bore pinches the outer ring of 6328-NTN and shows up later as two-point loaded raceway wear.
• The open 6328 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 140 mm bore places 6328 at the lower end of NTN's large-size range; at these diameters the pressed-steel cage is speed-limited and NTN commonly supplies a machined brass cage (suffix M) as an option. Verify cage material and relubrication interval with the NTN distributor, and do not extrapolate small-bore speed ratings to this size.
• NTN lists the grease limiting speed at 2200 r/min for 6328; this is a large or heavy-section size where centrifugal force and cage inertia cap the speed — for higher shaft speeds either step to a smaller bearing on the same bore or consult NTN for an oil-lubricated, machined-cage variant.
• NTN rates 6328 at 280 kN dynamic (C) and 246 kN static (C0), 13 kN fatigue load limit Cu; this is an upper heavy-load rating where the pressed-steel cage is not recommended — NTN supplies a machined brass cage (suffix M) and the static C0 must be verified against any shock or lifting loads the bearing sees during mounting.
• At 18500 g (18.5 kg), 6328 is a heavy bearing that requires a crane or hoist for handling; induction-heat the inner ring (max 120 °C) and use a mechanical puller for removal — never apply heat directly to the balls or cage.
• The 140×300×62 mm envelope of 6328 gives a D/d ratio of 2.14 and 80.0 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 280/246 kN load ratings, 13 kN fatigue load limit Cu NTN lists the grease limiting speed at 2200 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 18500 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6328 on the 140×300×62 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 6328 in a rated drive.
• Factory-fill grease in NTN sealed units is a general-duty lithium-soap grease; food-grade, low-temperature and high-temperature fills are request options at order time, because LLU/LLB units are not meant to be opened and re-greased in the field.
• 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.