6303-ZZ-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 6303-ZZ-NSK model number is decoded

6303-ZZ carries two non-contact sheet-steel shields that hold the factory grease in and keep coarse debris out; they do not seal against liquids. Within the medium 63xx section (diameter series 3 of ISO 15), multiplying bore code 17 by five gives the 17 mm bore; the 47 mm outside diameter and 14 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 17 mm shaft under normal load, catalogue practice seats it on a j5 shaft fit with an H7 housing bore — confirm against the actual load direction and magnitude before committing. NSK catalogue order number: 6303ZZ (suffix ZZ), two non-contact steel shields, mapped here from the industry-neutral -ZZ spelling.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Large bores like the 17 mm of 6303-ZZ-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.
• The 63xx medium section at 17 mm bore gains dynamic rating through larger rolling elements on a 47 mm OD; the penalty is mass and a lower limiting speed than the 6217 — do not specify it for speed-critical shafts.
• ZZ shields are non-contact: 6303-ZZ-NSK blocks chips and coarse dust but is not waterproof — do not install it expecting a pressure-wash seal, step up to 6303-2RS for that.
• Do not wash 6303-ZZ-NSK in solvent before mounting: the grease inside the shielded cavity is the service fill, and solvent creeping past the shield gap strips it out.
• The housing bore for the 47 mm OD should be round within IT7; an oval bore pinches the outer ring of 6303-ZZ-NSK and shows up later as two-point loaded raceway wear.
• Deep-groove ball bearings tolerate only minutes of misalignment; if the 47 mm housing cannot be aligned, switch to a self-aligning type rather than shimming 6303-ZZ-NSK.
• NSK catalogues the shielded version as 6303ZZ — suffix ZZ, two non-contact steel shields. The industry-neutral page spelling is -ZZ; quote the NSK order number when buying through an NSK channel.
• At 17 mm bore the 6303 sits in NSK's small-bore range; NSK ships these sizes with a pressed-steel cage and P0 tolerance as standard, and NSK's EA (extra-precision) or P5 class is a special-order upgrade for spindle duty — do not assume catalogue P0 figures hold for instrument use without an NSK engineering check.
• At 15 kN dynamic load rating (C) and 6.65 kN static (C0), 6303 is a medium-load NSK bearing suitable for most electric-motor and pump duty; the C0/C0r ratio matters for preloaded or thrust-loaded arrangements, so confirm the static safety factor with the NSK catalogue.
• At 113 g, 6303 is light enough for hand assembly but should be pressed on with a fitting sleeve against the inner ring; do not strike the outer ring or cage with a hammer.
• The 17×47×14 mm envelope of 6303 gives a D/d ratio of 2.76 and 15.0 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 15/6.65 kN load ratings, mass 113 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6303ZZ on the 17×47×14 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 6303 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.
• NSK supplies its sealed units pre-greased for general duty between roughly -10 and +110 °C; low-temperature, food-grade and high-temperature fills are special executions — ask at order time, because DDU/VV units are not designed to be opened and repacked.
• NSK does not recommend washing new shielded or sealed bearings; the rust-preventive film on open units is compatible with standard lithium greases and needs no removal unless the application demands a special fill.