6204 Bearing Dimensions

Tolerances and fits for 6204

FULI makes 6204 to P0 as standard, with P6 on request. P0 is the Normal tolerance class of ISO 492; P6 limits are tighter. These are the P0 limits for the 20 × 47 × 14 mm size.

Dimension	Nominal, mm	Deviation, µm	Limits, mm
Bore d (Δdmp)	20	0 / −10	20.000 / 19.990
Outside diameter D (ΔDmp)	47	0 / −11	47.000 / 46.989
Width B (ΔBs)	14	0 / −120	14.000 / 13.880

Δdmp and ΔDmp: deviation of the mean bore and mean outside diameter in one radial plane. ΔBs: inner ring width; the outer ring width has the same limits.

Shaft and housing fits (general guidance)

For an inner ring that turns with a solid steel shaft under normal load, bearing makers’ fit tables give 20 k5 for the shaft of 6204. The housing bore is usually H7, or J7 where the outer ring must not creep.

Seat	Deviation, µm	Limits, mm	Fit with 6204
Shaft 20 k5	+11 / +2	20.011 / 20.002	2 to 21 µm interference
Housing 47 H7	+25 / 0	47.025 / 47.000	0 to 36 µm clearance
Housing 47 J7	+14 / −11	47.014 / 46.989	11 µm interference to 25 µm clearance

Taking the loosest and the tightest combination of limits, a P0 6204 on a 20 mm k5 shaft has 2 to 21 µm interference. Its outer ring has 0 to 36 µm clearance in an H7 bore and 11 µm interference to 25 µm clearance in a J7 bore.

This is general guidance, not a FULI specification. Heavy or shock loads, a hollow shaft, a thin-walled, split or light-alloy housing, or a large temperature difference between shaft and housing call for other classes, and the drawing of your machine takes priority. A tight shaft fit or a hot housing uses up internal clearance, and that is when C3 is chosen instead of C0.

If the outer ring turns and the shaft stands still, as in an idler pulley or a wheel hub, the fits are reversed: the housing gets the interference fit (for example N7 or P7) and the shaft a sliding one (g6 or h6).

Sources: ISO 492 tables as printed in the NTN catalogue CAT. No. 2203/E (Tables 6.4 and 6.5) and the RKB tolerance catalogue; ISO 286-2 for the seats; SKF and NTN fit tables for the shaft and housing classes.

The 6204 bearing dimensions are 20 mm bore, 47 mm outside diameter and 14 mm width. It is one of the most common deep groove ball bearings on a 20 mm shaft. You find it in conveyor idler rollers, motorcycle engines and sprocket carriers, electric motors, pumps and small gearboxes. This page explains the designation, gives the catalog figures for our 6204, and lists the size mix-ups that are easy to make with this bearing, because several other bearings share either its bore or its outside diameter.

6204 bearing dimensions explained

A 6204 is a single row deep groove ball bearing in the 02 dimension series. The 6 is the bearing type, the 2 is the diameter series and 04 is the bore code [1].

From bore code 04 upwards the bore in millimetres is the code times 5, so 04 means 20 mm [1]. The 6204 is the first size in the 6200 series where that rule works. Codes 00 to 03 are fixed values (10, 12, 15 and 17 mm), which is why the 6203 is 17 mm and not 15.

The boundary dimensions follow the ISO 15 general plan [2], so 20 x 47 x 14 mm is the same in every catalogue.

In inches the 6204 is 0.7874 x 1.8504 x 0.5512 in. Our catalog gives a basic dynamic load rating Cr of 11.52 kN, a static rating C0r of 6.65 kN and limiting speeds of 15,000 r/min with grease and 17,000 r/min with oil. Values from FULI’s catalog; confirm for your application.

Each 6204 weighs 0.107 kg in our catalog, so 100 pieces are about 10.7 kg before boxes and cartons.

6204 load rating next to the alternatives

For a 20 mm shaft, our catalog figures are:

Model	Size (mm)	Cr (kN)	C0r (kN)	Weight (kg)
6004	20 x 42 x 12	8.46	4.85	0.068
6204	20 x 47 x 14	11.52	6.65	0.107
6304	20 x 52 x 15	14.31	7.58	0.145
6404	20 x 72 x 19	28.50	13.90	0.400

Values from FULI’s catalog; confirm for your application.

Each step up the series adds capacity and outside diameter. On a replacement the housing has already chosen for you. On a new design, the 6204 is the middle choice: about a third more dynamic rating than the 6004 for 5 mm more outside diameter.

6204ZZ, 6204-2RS or open

Version	Cover	Typical 6204 position
6204 open	None	Gearbox shafts and motorcycle crankshafts running in oil
6204ZZ	Two non-contact steel shields	Motors and machines in clean, dry places
6204-2RS	Two rubber contact seals, greased	Conveyor idlers, pumps, sprocket carriers, outdoor equipment

Sealed bearings keep dirt out better than shielded ones, and shielded better than open [3]. A conveyor idler running in coal, sand or grain dust needs the contact seal, and our conveyor bearings page lists the 6204-2RS among the idler sizes.

An open 6204 inside an engine or gearbox lives on the oil around it. Swapping in a sealed bearing shuts the oil out and leaves only the grease packed at the factory.

Seal and shield codes differ between makers. NSK, for example, uses ZZ for shields and DDU for contact rubber seals on both sides [3]. Our 6200 series cross-reference lists the common suffixes side by side.

6204 clearance: what to write on the order

A bearing with no clearance suffix is Normal clearance, CN or C0. For a bore over 18 up to 24 mm, which covers the 6204, NTN’s table gives C2 as 0 to 10 μm, CN as 5 to 20 μm and C3 as 13 to 28 μm [4].

NSK lists larger-than-normal clearance for tight fits on both rings, an inner ring that runs hotter than the outer, heavy or shock loads and high speeds [5]. Smaller clearance suits positions where noise, vibration and running accuracy matter more [5].

Motorcycle crankshaft positions are a case where the old bearing often carries C3 or a special clearance mark. Copy it from the ring. Clearance is set on automatic assembly equipment in our factory and checked periodically during production. It cannot be changed afterwards, so it belongs in the order code: 6204-2RS C3, not “6204, C3 if possible”.

Where the 6204 is used

These positions are listed on our application pages:

• Conveyor bearings: idler rollers, usually 6204-2RS, alongside 6205, 6305 and 6306.
• Motorcycle bearings: sprocket carriers, crankshafts and gearbox shafts.
• Electric motor bearings and water pump bearings: the 20 mm shaft line, with the 6304 as the heavier option.
• Gearbox bearings: input and intermediate shafts in small reducers.

A deep groove ball bearing carries radial load and some axial load in both directions [3]. That is enough for an idler or a motor. Where a shaft has heavy axial load in one direction, a gearbox often uses a tapered roller bearing in the same outside diameter instead, as described below.

Common 6204 ordering mistakes

The 6303 drops into a 6204 housing. The 6303 is 17 x 47 x 14 mm. Outside diameter and width match the 6204 exactly, and only the bore is different. If the old bearing is worn beyond reading and the buyer measures only the housing, a 6303 can be shipped and accepted. It will not go on a 20 mm shaft. Always measure the bore.

Same outside diameter, other bearings. The 6005 is 25 x 47 x 12 mm and the 16005 is 25 x 47 x 8 mm. The 30204 tapered roller bearing is 20 x 47 x 15.25 mm, with the same bore and outside diameter as the 6204 but a total width of 15.25 mm and a separate cone and cup. A tapered bearing in a deep groove position, or the other way round, changes how the shaft is located. Keep to the type the machine was built with.

UC204 in place of 6204. The UC204 insert bearing has a 20 mm bore and 47 mm outside diameter, but our catalog gives its inner ring width as 31 mm. It has set screws and a sphered outer ring for a housing unit. Same two numbers, different part.

Same 20 mm bore, other series. On our specification sheet the 20 mm bore covers 6804 (20 x 32 x 7), 6904 (20 x 37 x 9), 16004 (20 x 42 x 8), 6004, 6204, 6304 and 6404. The bore alone narrows nothing down.

Letters left off. Many inquiries say “6204” and nothing else. The bare number means an open bearing with Normal clearance. Write the seal, shield and clearance codes in full. Our guide on how to avoid ordering the wrong bearing shows where each letter goes.

How to measure a 6204

1. Clean the bearing and measure the bore at two points, 90° apart: 20 mm.
2. Measure the outside diameter at two points: 47 mm.
3. Measure the width across both rings: 14 mm.
4. Read the ring face or shield for the designation and suffix letters.
5. Check the cover on each side: rubber seal, steel shield or open.

If you get 20, 47 and 14 mm, it is a 6204 whatever brand is on the ring. If the bore is 17 mm, it is a 6303. For other combinations, our bearing size finder finds the size from the measurements.

How we supply the 6204

Our 6204 rings and balls are GCr15 chrome bearing steel, and the steel maker’s material certificate is available on request for OEM and industrial orders. Precision is P0 as standard, P6 on request.

Sealed and shielded 6204 bearings are greased to about 30% of the free space inside the bearing. We set the filling machine by weighing sample bearings before and after filling. If your application needs a different fill or a particular grease, write it in the inquiry and we will confirm what we can supply. Our grease fill calculator shows what a fill percentage means in grams.

Deep groove ball bearings are tested on vibration and noise instruments and shipped at Z3V3 as standard. A bearing of a lower noise grade fitted in equipment that needs a quieter grade will sound noisy even when it is made correctly. Our article on bearing noise grade and precision class explains the difference.

Before shipment each batch is checked for rotation smoothness, dimensions, grease fill, rust and appearance. Boxes show the model, grade and brand. Rings carry your authorised brand, our factory brand or no brand, as you require. If your parts list gives an OEM number for this position, send it and we will confirm the standard model before quoting.

Neighbouring sizes

Model	Bore (mm)	OD (mm)	Width (mm)	Note
6203	17	40	12	One size down
6204	20	47	14	This page
6205	25	52	15	One size up
62/22	22	50	14	Intermediate size
6004	20	42	12	Same bore, lighter
6304	20	52	15	Same bore, heavier
6303	17	47	14	Same OD and width, smaller bore

The full 6200 series runs from 6200 to 6220. Send the model, suffix, clearance and quantity to sales@fuli-bearings.com or WhatsApp +86 152 6352 1305.

Sources

1. SKF Rolling bearings catalogue (PUB BU/P1 17000/1 EN) (SKF)
2. ISO 15:2017 Rolling bearings - Radial bearings - Boundary dimensions, general plan (preview) (ISO via iTeh Standards)
3. Deep Groove Ball Bearings (product page) (NSK)
4. NTN Ball and Roller Bearings catalog 2203-E, Section 8: Bearing internal clearance and preload (NTN)
5. Fits and Internal Clearance (ABC of bearings) (NSK)