6312-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 6312-NTN model number is decoded

6312 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 12 by five gives the 60 mm bore; the 130 mm outside diameter and 31 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 60 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

• Interference on a 60 mm shaft plus running heat consumes radial clearance: where the shaft runs hot or the fit is tight, order 6312 with C3 clearance and re-check the residual value after mounting.
• The 63xx medium series gains rating at 60 mm bore through a 130 mm OD and 31 mm width; the heavier rolling elements also trade away some speed versus a 6212.
• The open 6312-NTN has no lubricant retention: grease escapes and contaminants migrate straight into the 60×130×31 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Storage matters for open bearings: 6312-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.
• Never mix components between two 6312-NTN units: rings, cage and balls are factory-matched and are not field-interchangeable, even between identical designations.
• Deep-groove ball bearings tolerate only minutes of misalignment; if the 130 mm housing cannot be aligned, switch to a self-aligning type rather than shimming 6312-NTN.
• The open 6312 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.
• At 60 mm bore 6312 is in NTN's upper general-purpose range; the pressed-steel cage is standard but mid-section 63xx sizes at this bore can be ordered with a machined brass cage (suffix M) for heavy-shock or very-low-speed duty — confirm cage material with the NTN channel if the application sees impact loads.
• At 5400 r/min the grease limiting speed for 6312 covers medium-duty industrial drives; the open or shielded execution can run continuously at this speed with standard lithium-soap grease.
• At 90.5 kN dynamic load rating (C) and 52 kN static (C0), 4.1 kN fatigue load limit Cu, 6312 is a heavy-load bearing for industrial gearboxes and large conveyors; NTN expects a machined brass cage (suffix M) at this rating for shock duty, and the static C0 must be checked against any mounting or lifting loads.
• At 1730 g (1.7 kg), 6312 needs mechanical handling for mounting; NTN recommends induction heating the inner ring (max 120 °C) rather than pressing cold, and a lifting eye if the housing is pre-assembled.
• The 60×130×31 mm envelope of 6312 gives a D/d ratio of 2.17 and 35.0 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 90.5/52 kN load ratings, 4.1 kN fatigue load limit Cu NTN lists the grease limiting speed at 5400 r/min for this designation; oil-mist or jet lubrication raises the ceiling but requires a sealed-housing review. and 1730 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6312 on the 60×130×31 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 6312 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.
• NTN's pressed-steel cage (no cage suffix) is the quiet standard for this size; for sustained running close to the limiting speed or for heavy shock duty, ask the NTN channel whether a machined-cage execution of 6312 is listed.