How to Read INA Codes: Designation Structure, Prefixes, Suffixes, and Real Examples

When you work with INA bearings, the code is not just a catalog number: it is a compact technical description. Each designation follows rules established by DIN 623 and the INA system, which allows you to identify the bearing type, dimensional series, bore diameter, and special features such as seals or cages.

For a maintenance manager or buyer, understanding this nomenclature prevents errors when ordering spare parts and speeds up finding the correct bearing. At MR, we work with a wide INA line, which includes needle roller bearings, Y inserts, cam followers, cylindrical roller thrust bearings, needle cages, and freewheels, among others.

In this guide, we show you how a typical INA code is structured, what the most common prefixes and suffixes mean, and give you real examples of the products we distribute.

An INA code consists of a prefix (one or more letters), a main number that indicates the series and size, and sometimes suffixes that add information about internal design, seals, cage, or precision. For example, in a needle roller bearing, the prefix IR indicates an inner ring, while NAO designates a needle roller bearing without an inner ring.

The main number usually follows a dimensional logic: in many cases, the last two digits multiplied by 5 give the bore diameter in millimeters (as in deep groove ball bearings), but in needle roller bearings and other types, the number refers to the series and size according to specific tables.

Suffixes can indicate, for example, that the bearing has a steel sheet cage (suffix M), seals (2RS), or greater internal clearance (C3). It is important to consult the INA catalog to confirm the exact meaning of each suffix in the context of the bearing type.

In the needle roller bearing line, prefixes identify specific components. For example, IR designates an inner ring for needle roller bearings, such as the codes IR65 and IR12 that we distribute. These rings are used as raceways when the shaft cannot be ground and hardened.

The prefix NAO corresponds to a needle roller bearing without an inner ring, such as NAO9. This type is mounted directly on a ground and hardened shaft, allowing a compact design and high radial load capacity.

Other frequent prefixes are K for needle cages (such as K130, K165, and K210), GS for shaft washers in cylindrical roller thrust bearings (for example, GS81115 and GS81214), and KR for stud-type cam followers, such as KR35, KR22, and KR40.

Suffixes in INA codes provide key information about design and performance. For example, the suffix M in a cylindrical roller thrust bearing such as 81232-M indicates a machined brass cage, suitable for high speeds and loads.

In Y-bearings (inserts), suffixes can indicate the type of shaft attachment. For example, the codes UC209, UK217, and UC205 correspond to inserts with set screws (UC series) or with adapter sleeve (UK series). These inserts are mounted in pillow block or flanged housings.

Other common suffixes include 2RS for rubber seals on both sides, C3 for radial clearance greater than normal, and EJ for a steel sheet cage with a specific design. It is always advisable to verify the INA catalog for the exact meaning in each series.

To see the nomenclature in action, here are some codes from our INA line. In needle roller bearings, IR65 is an inner ring with a bore diameter of 65 mm (depending on the series), and NAO9 is a needle roller bearing without an inner ring of the NAO series.

In Y inserts, UC209 is an insert with set screws and a bore diameter of 45 mm (depending on the UC series), while UK217 is an insert with adapter sleeve for 75 mm shafts. These inserts are used in agricultural applications, conveyors, and general machinery.

In cam followers, KR35 is a stud-type roller with an outer diameter of 35 mm, and KR22 has an outer diameter of 22 mm. In cylindrical roller thrust bearings, 81232-M is a thrust bearing of the 812 series with a brass cage, and GS81115 is a shaft washer for bearing 81115.

To request a quote, it is best to provide us with the complete code of the bearing, as it appears on the part or on the equipment plate. If you do not have the code, you can send us the main dimensions (inner diameter, outer diameter, and width) and a photo of the part.

At MR, we work with the INA line and help you identify the correct bearing from the designation or dimensions. We also indicate the appropriate alternative if the original code has been discontinued or replaced.

Remember that an incorrect designation can lead to improper mounting or premature failure. Therefore, if you have any doubt, consult us and we will guide you in the selection.

Below we answer some common questions we receive from customers about interpreting INA codes. If you have another question, write to us via WhatsApp or email and we will respond promptly.

Our technical-commercial team is accustomed to working with INA designations and can help you decipher any code, even if it is partially erased or if you only have a photo of the part.