How to Read NTN Codes: Structure, Prefixes, and Suffixes

When you have to replace a bearing in a machine, the code engraved on the part is the key to ordering the correct replacement. NTN, one of the world's leading bearing manufacturers, uses a standardized designation system that, once you understand it, allows you to identify type, dimensions, and special features at a glance.

In Argentine industry, NTN bearings are present in a wide variety of equipment: electric motors, pumps, gearboxes, agricultural machinery, and more. Knowing how to interpret their nomenclature saves you costly errors and unnecessary downtime.

In this guide, we show you how an NTN code is structured, what the most common prefixes and suffixes mean, and how you can use that information to get a quote for the bearing you need.

The designation of an NTN bearing consists of three main parts: a prefix (optional), a basic code, and one or more suffixes. The basic code identifies the bearing type and its main dimensions, while prefixes and suffixes add information about materials, internal design, seals, cage, or internal clearance.

For example, in a code like 6205ZZ, the basic number 6205 indicates a deep groove ball bearing of the 62 series with a 25 mm bore, and the suffix ZZ indicates that it has two metal shields. If the bearing had a prefix, it would appear before the basic number.

It is important not to confuse the NTN designation with that of other brands: although many manufacturers follow similar ISO standards, suffixes can vary. Therefore, when ordering a replacement, it is advisable to verify the complete code as it appears on the part or in the equipment manual.

The basic code of an NTN bearing follows a numeric pattern. In metric bearings, the last two digits of the basic number usually indicate the bore diameter multiplied by 5. For example, in 6205, the 05 corresponds to a 25 mm bore (05 x 5 = 25). For diameters less than 20 mm, there are special rules.

The preceding digits identify the dimensional series, which defines the width and outer diameter for the same bore diameter. For example, the 62 series is a light series, while the 63 is a medium series. This allows you to choose the appropriate bearing according to load and available space.

In addition to the basic type, NTN uses prefixes to indicate design or material variants. For example, the prefix 4T is used for tapered roller bearings with special heat treatment. Knowing these details helps you select the correct replacement without relying only on the measurement.

Suffixes are letters or combinations of letters added at the end of the basic code to indicate specific features. Some of the most common in NTN bearings are: ZZ (two metal shields), LLU (two rubber contact seals), C3 (internal clearance greater than normal), and P5 (higher dimensional precision).

You may also find suffixes that indicate the cage material, such as J for steel sheet cage, or L1 for machined brass cage. In tapered roller bearings, suffixes like EJ identify a specific internal design with higher load capacity.

It is essential to read the complete suffix, because each letter has a meaning. For example, a 6205ZZ bearing is not the same as a 6205LLU: the first has metal shields and the second has rubber seals, which changes protection against contaminants and friction.

To see how the nomenclature is applied, let's analyze some typical examples. The code 6205ZZ corresponds to a deep groove ball bearing, 62 series, 25 mm bore, with two metal shields. It is widely used in electric motors and household appliances.

Another example is 4T-32210, a tapered roller bearing with prefix 4T (special heat treatment) and basic number 32210, which indicates the 322 series with a 50 mm bore. This type is used in gearboxes and vehicle wheels.

A third case: UC205, a ball bearing with a pillow block housing, from the UC series, with a 25 mm bore. The letter U indicates that it is a bearing with a spherical outer ring, designed to be mounted in housings. These examples show how the code gives you key information for replacement.

When you need a quote for an NTN bearing, the safest way is to send the complete code as engraved on the part or on the equipment plate. If the code is blurred, you can measure the main dimensions (bore, outer diameter, and width) and send them along with a photo.

At MR Accesorios Industriales, as an official NTN distributor in Buenos Aires, Argentina, we sell NTN bearings and can advise you on interpreting codes and selecting the right replacement for your application.

Do not hesitate to contact us: we will provide a quote for the NTN bearing you need promptly, indicating the best option according to your equipment and working conditions.

Below we answer some common questions we receive from maintenance managers and industrial buyers. If you have another question, write to us via WhatsApp or email and we will help you.

Remember that correct bearing identification prevents prolonged downtime and ensures the reliability of your machinery. At MR we are here to support you in that process.