6218-NSK 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 6218-NSK model number is decoded

6218 is supplied open, without shields or seals, so the arrangement around it must supply and retain the lubricant. Within the light 62xx section (diameter series 2 of ISO 15), multiplying bore code 18 by five gives the 90 mm bore; the 160 mm outside diameter and 30 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 90 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 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

• Large bores like the 90 mm of 6218-NSK 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.
• At 90 mm bore the 62xx light series is the workhorse section; its 160×30 mm envelope is what most motor and gearbox seats are machined for, so any alternative section must be checked against both this OD and this width, not the bore alone.
• Storage matters for open bearings: 6218-NSK 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.
• Open bearings tolerate the highest speeds in the 6200-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 6218 units.
• Grease compatibility is not guaranteed between fills: mixing lithium and polyurea thickeners in a 6200-series position can soften the mixture and leak — clean out the old fill before switching grease types.
• A 90 mm bore listing showing the right d/D/B but no standard or precision-class reference may be a loose-tolerance import; measure bore/OD spread before fitting it to a machined shaft.
• The open 6218 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.
• At 90 mm bore 6218 is in NSK's medium industrial range; the pressed-steel cage is standard, but large-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 NSK channel if the application sees impact loads.
• At 106 kN dynamic load rating (C) and 71.5 kN static (C0), 6218 is a heavy-load NSK bearing for industrial gearboxes and large conveyors; NSK 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 2180 g (2.2 kg), 6218 needs mechanical handling for mounting; NSK recommends induction heating the inner ring (max 120 °C) rather than pressing cold, and a lifting eye if the housing is pre-assembled.
• The 90×160×30 mm envelope of 6218 gives a D/d ratio of 1.78 and 35.0 mm radial section height — a standard NSK medium section that balances load capacity and speed; for this geometry the pressed-steel cage is adequate up to NSK's listed speed ratings, and C3 clearance is the common choice for hot shafts.
• The 106/71.5 kN load ratings, mass 2180 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6218 on the 90×160×30 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 6218 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 6218 — a new bearing pressed onto a worn or oval seat reproduces the original failure mode in a fraction of its expected life.
• Keep NSK bearings in the original packaging until fitting: the wrapper carries the production lot, and the unopened shelf life of greased sealed units is typically quoted at three to five years in dry, vibration-free storage.