EZO is a bearing brand of the Japanese Kitanihon Seiki group, with global sales handled by Sapporo Precision. EZO specializes particularly in miniature and small-size ball bearings, as well as stainless steel, thin-section, flanged, inch-size and miniature thrust ball bearings. The wide range of dimensions and design variants makes EZO particularly relevant when standard bearing series cannot meet the dimensional or technical requirements of a compact or precision mechanism.
EZO - a specialist in small-size bearings
One of the most characteristic areas of the EZO range is bearings with small overall dimensions. In such designs, limited installation space requires precisely defined bore diameters, outside diameters, widths and bearing locating methods.
The EZO range includes conventional miniature deep groove ball bearings as well as very compact bearings from the 67, 68 and 69 series, flanged versions, stainless steel variants and inch-size series.
For example, EZO 682ZZ 2x5x2.3 mm has a bore diameter of only 2 mm and an outside diameter of 5 mm. In comparison, EZO 6803ZZ 17x26x5 mm is considerably larger but still provides a very small radial cross-section relative to its bore.
This illustrates why the term "EZO miniature bearings" does not refer to one specific series. It covers numerous bearing designs intended for different installation spaces and operating conditions.
How to read EZO bearing designations
With EZO bearings, the complete bearing designation should always be considered. The basic bearing number alone may not be sufficient to identify the exact version.
For example:
605 - basic open bearing,
605ZZ - version with metal shields on both sides,
605-2RS - version sealed on both sides,
605HZZ - stainless steel version with metal shields.
The basic dimensions may remain unchanged, while the bearing construction and operating characteristics differ.
This leads to one of the most important rules when selecting EZO bearings:
The basic bearing number identifies the bearing family and size, while additional designation elements identify the specific version.
Individual letters should also never be interpreted without considering the complete bearing series. The same character appearing in different product families does not necessarily have the same meaning.
EZO miniature ball bearings
Miniature deep groove ball bearings consist of an inner ring, outer ring, balls and cage. Their deep raceway geometry is designed primarily to accommodate radial loads while also allowing axial loads in both directions within the operating limits of the particular bearing.
In miniature bearings, parameters that may sometimes receive less attention in larger bearings become especially important.
The difference between a width of 3 mm and 4 mm, or between a 6 mm and 6.35 mm bore, is significant from a design and interchangeability perspective.
When identifying a miniature bearing, it is therefore important to determine:
- bore diameter d,
- outside diameter D,
- width B,
- closure type,
- material,
- presence of a flange,
- complete designation.
Only this combination of information allows the correct bearing to be identified reliably.
Metric and inch-size EZO bearings
EZO manufactures both metric and inch-size bearings.
This distinction is particularly important with miniature bearings.
A dimension of:
6.35 mm
is not an inaccurately manufactured 6 mm bore. It corresponds to:
1/4 inch.
Similarly:
12.7 mm = 1/2 inch
and:
4.7625 mm = 3/16 inch.
A good example is EZO SR188ZZ 6.35x12.7x4.763 mm, whose nominal dimensions correspond to 1/4x1/2x3/16 inch.
Rounding a 6.35 mm bore down to 6 mm during identification would therefore lead to an entirely different bearing.
When measuring small bearings, values characteristic of the imperial system should always be considered before selecting a metric equivalent.
EZO thin-section bearings
When radial installation space is limited, bearings with a small radial cross-section become particularly useful.
Important examples include the 67, 68 and 69 series.
A good example is:
EZO 6803ZZ 17x26x5 mm.
Despite its 17 mm bore, the bearing has an outside diameter of only 26 mm and a width of 5 mm.
Another example is:
EZO 6904-2RS 20x37x9 mm.
Bearings of this type make it possible to reduce the space required for the bearing arrangement. However, this does not mean that any thin-section bearing with similar dimensions can automatically be used as a replacement.
The reduced cross-section affects the rings, balls and overall internal geometry. Load ratings should therefore always be checked for the exact bearing rather than transferred from another series with a similar bore diameter.
EZO stainless steel bearings
Another important part of the EZO range is stainless steel bearings.
In relevant product families, the designation H is used for stainless steel versions, for example:
605HZZ,
6700HZZ,
686HZZ.
Stainless steel versions are particularly useful when operating conditions require increased corrosion resistance.
However, a stainless steel bearing should not be interpreted as completely resistant to every environment.
Actual corrosion resistance depends on factors such as:
- type of medium,
- humidity,
- temperature,
- chemicals,
- exposure time,
- lubricant.
The term stainless steel bearing therefore describes a material characteristic, not a guarantee of universal chemical resistance.
The bearing material should always be matched to the actual operating environment.
EZO flanged bearings
A flange on the outer ring can simplify axial positioning of the bearing in its housing.
This is particularly useful in miniature mechanisms, where machining an additional locating shoulder in a very small housing may be difficult.
An example is EZO F-686HZZ 6x13x5 mm, a miniature stainless steel bearing with a flange and metal shields.
The dimensions 6x13x5 mm describe the basic bearing dimensions. When designing a housing for a flanged version, the actual flange geometry must also be checked.
This is equally important when considering interchangeability.
A standard:
6x13x5 mm bearing
and a flanged:
6x13x5 mm bearing
may share the same basic dimensions but are not the same component from a mounting perspective.
The letter F does not always mean the same thing
One of the easiest mistakes to make with EZO designations is interpreting an individual character without first identifying the product family.
In a designation such as F-684ZZ, the bearing is a miniature flanged deep groove ball bearing.
This does not mean that:
F6-14M
or:
F8-16M
are flanged versions of conventional radial ball bearings.
These designations belong to a family of miniature thrust ball bearings.
The correct approach is therefore:
first identify the bearing family and bearing type, and only then interpret the individual elements of the designation.
This is more reliable than applying a universal rule such as "F means flange."
EZO miniature thrust ball bearings
Thrust bearings are designed for a fundamentally different purpose from conventional deep groove ball bearings.
Examples include:
EZO F6-14M 6x14x5 mm
and:
EZO F8-16M 8x16x5 mm.
These are miniature ball bearings designed primarily to accommodate axial loads.
They should not be confused with radial bearings simply because their bore and outside diameter may correspond to dimensions found in other bearing series.
This leads to an important selection rule:
Dimensional compatibility does not necessarily mean functional compatibility.
A radial bearing and a thrust bearing may fit within a similar installation envelope, but their ability to carry loads is determined by their internal construction.
ZZ - metal shields on both sides
One of the most common EZO suffixes is ZZ.
It indicates metal shields on both sides of the bearing.
The shields help limit the entry of contaminants into the bearing and retain lubricant. They should not be confused with contact elastomer seals.
Metal shields are particularly useful where protection of the bearing interior is required without the additional friction associated with contact sealing.
Examples include:
608ZZ,
698ZZ,
6803ZZ,
MR128ZZ,
SR188ZZ.
In each case, ZZ identifies shields on both sides, while the remaining designation determines the bearing family, dimensions and material version.
2RS - seals on both sides
The designation 2RS identifies a bearing sealed on both sides.
Examples include:
EZO 605-2RS 5x14x5 mm
and:
EZO 63801 2RS 12x21x7 mm.
Compared with ZZ metal shields, a contact sealing arrangement provides different protection against contamination but also introduces different friction characteristics.
For this reason, asking:
"Is 2RS better than ZZ?"
is not technically precise.
The correct question is:
"Which closure design is appropriate for the operating conditions of the bearing arrangement?"
If low friction and high rotational speed are priorities, the requirements may differ from those of a mechanism exposed to dust or contamination.
Open, ZZ and 2RS EZO bearings
The fundamental differences can be summarized as follows:
| Version | Closure | Main characteristic |
|---|---|---|
| Open | None | Direct access to raceways and rolling elements |
| ZZ | Metal shields | Protection without contact sealing |
| 2RS | Seals | Increased protection of the bearing interior |
One version should not automatically be substituted for another.
In a mechanism designed for a particular speed, lubrication method and friction level, the closure type is part of the technical specification.
Cages in EZO bearings
The cage maintains the correct spacing between the balls and participates in guiding the rolling elements during operation.
It should not be assumed that all EZO bearings use the same cage.
Different cage materials and guiding arrangements can be used depending on the bearing series and specific version.
For this reason, statements such as:
"steel cage"
or:
"plastic cage"
should only be made after checking the specification of the exact bearing.
This is particularly important for less conventional product families such as miniature thrust bearings.
Cage construction can influence operating characteristics including speed capability, friction, temperature behaviour and compatibility with specific operating conditions.
Internal clearance is not a quality grade
Another parameter that should not be interpreted as a marketing feature is internal clearance.
Standard clearance may be identified as CN, while other clearance ranges can be specified for particular applications.
Greater internal clearance does not mean that a bearing is better.
Clearance is selected according to operating conditions, including:
- inner-ring fit,
- outer-ring fit,
- operating temperature,
- rotational speed,
- differences in thermal expansion.
After installation on a shaft and in a housing, the operating clearance may be smaller than the bearing's initial clearance.
Incorrect clearance selection can therefore result in excessive internal loading or, at the opposite extreme, excessive movement in a system requiring precise guidance.
C and C0 - what do bearing load ratings mean?
Two important parameters commonly found in ball bearing specifications are:
C - basic dynamic load rating
and:
C0 - basic static load rating.
These values should not simply be interpreted as the "maximum weight" that can be placed on a bearing.
The dynamic load rating is used in calculations concerning bearing fatigue life under rotation.
The static load rating relates to loading conditions in which permanent deformation at the rolling-element and raceway contacts becomes relevant.
For thrust bearings, corresponding ratings are used for axial loading.
C and C0 values should always be taken from the technical data for the specific EZO bearing.
Load ratings from SKF, NSK, NTN or another manufacturer should not be copied simply because the basic bearing designation and dimensions appear identical.
Catalogue speed and actual bearing operating speed
A speed value given in a bearing catalogue should not be interpreted as a guarantee that the bearing can operate continuously at that speed in every machine.
Actual operating capability also depends on:
- load,
- lubrication,
- temperature,
- heat dissipation,
- fits,
- mounting accuracy,
- closure type.
This is particularly important for miniature bearings, which may operate at very high rotational speeds.
When comparing two EZO versions, it is therefore important to consider not only dimensions and load ratings but also the conditions under which the specified speed applies.
How to select an EZO replacement bearing correctly
The safest starting point is the complete designation of the original bearing.
For example, if the original bearing is:
EZO 686HZZ
the replacement search should not be reduced simply to:
686.
The complete designation identifies a specific material version and closure configuration.
When evaluating an alternative bearing, check the following:
- bearing type,
- bore diameter d,
- outside diameter D,
- width B or height H,
- material,
- closure type,
- flange and its geometry,
- internal clearance,
- precision class where required,
- cage,
- load ratings,
- permissible speed,
- lubrication,
- any special specifications.
Only after these characteristics have been compared can true interchangeability be assessed.
How to identify an EZO bearing when the designation is unreadable
If the marking on an old bearing has worn away, identification should begin with accurate measurement.
Measure:
d - bore diameter,
D - outside diameter,
B - width.
If the bearing has a flange, the flange diameter and width should also be measured.
Then determine:
- whether the bearing is open,
- whether it has metal shields,
- whether it has seals,
- whether it has a flange,
- whether the dimensions may be imperial,
- whether it is a radial or thrust design.
A standard ruler is not sufficiently accurate for identifying miniature bearings.
The difference between 6 mm and 6.35 mm can completely change the bearing identification.
Why identical dimensions do not necessarily mean identical bearings
This is one of the most important principles in bearing selection.
Suppose two products both measure:
8x16x5 mm.
This only tells us that they occupy a similar basic installation envelope.
It does not tell us:
- whether both are radial bearings,
- whether one is a thrust bearing,
- what raceway geometry they use,
- what rolling elements they contain,
- their internal clearance,
- material,
- cage design,
- load ratings,
- closure type,
- precision.
A dimensional bearing search is therefore an excellent tool for narrowing the selection, but it should not be the sole basis for a technical decision.
Common mistakes when selecting EZO bearings
Most identification errors result from ignoring part of the bearing designation.
Typical mistakes include:
- replacing ZZ with 2RS without considering operating conditions,
- ignoring a stainless steel version,
- overlooking a flange,
- rounding an inch dimension to the nearest metric size,
- selecting a bearing solely by d, D and B,
- treating a thrust bearing as a radial bearing,
- assuming a cage type without checking the specification,
- copying load ratings from another bearing brand,
- interpreting greater internal clearance as "higher quality."
With miniature bearings, dimensional rounding is particularly risky. A difference of only a few tenths of a millimetre may indicate a completely different bearing series.
Installing miniature EZO bearings
Small dimensions require accurate installation.
The fundamental rule is:
Mounting force should not be transmitted through the rolling elements.
When the inner ring is press-fitted onto a shaft, mounting force should be applied to the inner ring.
When the outer ring is press-fitted into a housing, force should be applied to the outer ring.
Direct pressure should not be applied to:
- ZZ shields,
- seals,
- the cage.
Cleanliness is equally important.
In a miniature bearing, even a very small contaminant particle can be significant relative to the size of the balls and raceway contact surfaces. Clean installation conditions are therefore fundamental to reliable operation.
FAQ - EZO bearings
Is EZO a Japanese bearing brand?
Yes. EZO is a bearing brand of the Japanese Kitanihon Seiki group and is particularly associated with miniature, small-size and specialized ball bearings.
What is EZO best known for?
An important part of the EZO range consists of miniature and small-size ball bearings. The portfolio also includes stainless steel, thin-section, flanged, inch-size and miniature thrust bearing versions.
What does ZZ mean on an EZO bearing?
ZZ indicates metal shields on both sides of the bearing.
What does 2RS mean on an EZO bearing?
2RS indicates seals on both sides. This is a different closure design from ZZ metal shields.
What does H mean in an EZO designation?
In relevant EZO product families, H identifies a stainless steel version. It should always be interpreted as part of the complete bearing designation.
Does EZO manufacture inch-size bearings?
Yes. EZO offers miniature bearings with imperial dimensions. Values such as 6.35 mm and 12.7 mm should therefore not be rounded to nearby metric dimensions during identification.
Does F always mean a flanged EZO bearing?
No. The meaning must be determined in the context of the specific bearing family. F-684 is an example of a flanged bearing, while F6-14M is a miniature thrust ball bearing.
Can an EZO bearing be replaced by SKF, NSK, NTN or another brand?
Potentially, but the required technical parameters must match. Dimensions alone are not sufficient. Bearing type, construction, material, closure, clearance, load ratings, speed capability and any special specifications must also be checked.
Is ZZ better than 2RS?
Neither design is universally better. ZZ and 2RS provide different closure characteristics, and the correct choice depends on contamination, friction, speed, lubrication and other operating requirements.
Is a stainless steel EZO bearing completely corrosion-proof?
No. Stainless steel provides increased corrosion resistance, but actual resistance depends on the environment, temperature, medium and operating conditions.
EZO bearings at simmering.pl
At simmering.pl, EZO bearings are selected according to their complete designation and actual technical specification rather than dimensions alone.
This is particularly important with miniature bearing series, where visually similar products can differ in material, closure type, flange geometry, dimensional system or internal construction.
TG Ersatzteile Polska Sp. z o.o. has been operating since 2002. Bearings and industrial components are shipped from our warehouse in Poland, with personal collection also available from our store and warehouse in Lublin.
EZO bearings - key information
EZO is a Japanese bearing brand specializing particularly in miniature and small-size bearings. Its range also includes stainless steel, thin-section, flanged, metric, inch-size and thrust bearing designs. Correct EZO bearing selection requires checking the complete designation, dimensions, material, closure, internal clearance, cage and operating parameters. Matching dimensions alone do not confirm full interchangeability.