NJ306EM Axial Radial Cylindrical Roller Bearings For Machine Tool Industry

NJ306EM Cylindrical Roller Bearing: High-Load, Stable & Durable For Industrial Use

I. Product Overview

The NJ306EM cylindrical roller bearing is a key element in the machinery realm, playing a crucial role in enabling seamless power transfer and ensuring the stable running of equipment. As a member of the single - row cylindrical roller bearing series, it has an inner diameter of 30mm, an outer diameter of 72mm, and a width of 19mm. This dimensional combination strikes a balance between compactness and significant load - bearing capabilities, making it suitable for a wide range of mechanical applications with diverse operating conditions.

II. Structural Design

1. Rolling Elements

The rolling elements of the NJ306EM bearing are precision - made cylindrical rollers. These rollers are crafted from high - quality high - carbon chromium bearing steel through a series of elaborate precision machining processes. The outcome is an extremely low surface roughness, with dimensional accuracy maintained within a tight micrometer - level tolerance. The cylindrical shape of the rollers allows for line contact with the raceways. In comparison to point - contact bearings, this line - contact design greatly expands the contact area, facilitating more even load distribution. This not only significantly boosts the bearing's radial load - carrying capacity but also effectively reduces local wear, thus substantially prolonging the bearing's service life.

2. Raceways

Both the inner and outer ring raceways of the bearing are processed using super - finishing grinding techniques. This results in a surface hardness reaching up to HRC60 - 65, endowing the raceways with excellent wear - resistance and fatigue - resistance properties. The geometric parameters of the raceways are precisely calculated to perfectly match the cylindrical rollers. This ensures that the rollers can roll smoothly within the raceways, minimizing the friction coefficient and reducing vibration and noise during operation. Such a design provides a solid foundation for the efficient and stable operation of the bearing.

3. Cage

An integral metal - machined cage, typically fabricated from high - strength alloy steel, is used in the NJ306EM bearing. The cage undergoes special heat treatment processes to enhance its rigidity and toughness. The pocket size accuracy of the cage is extremely high. It serves to accurately guide and separate the cylindrical rollers, preventing collisions and frictions among them. This ensures that the rollers maintain an orderly arrangement even during high - speed operation, thus enhancing the overall stability of the bearing and further extending its service life. In certain models, such as those with a polyamide cage, it offers good self - lubrication properties and can reduce the noise during operation.

4. Rib Structure

The outer ring of the NJ306EM bearing is designed with double ribs, while the inner ring has a single rib. This rib configuration gives the bearing a certain degree of axial load - carrying capacity. It can withstand one - way axial forces and simultaneously performs an axial positioning function for the shaft or housing. By restricting the displacement of the shaft or housing in a specific direction, the bearing can operate stably even when subjected to combined loads, ensuring the reliability of the mechanical system.

III. Performance Characteristics

1. High Radial Load - Carrying Capacity

Due to the line - contact design between the cylindrical rollers and the raceways, the NJ306EM bearing exhibits an outstanding radial load - carrying capacity. Its basic rated dynamic load can reach a relatively high value (with specific values depending on actual product specifications). This enables it to easily handle the substantial radial forces generated during the operation of heavy - duty machinery, such as in the main shaft support systems of medium - sized industrial motors, precision machine tools, and various heavy - load transmission devices.

2. Good Axial Load - Carrying Performance

Although mainly designed to bear radial loads, the unique rib structure of the NJ306EM bearing allows it to withstand a certain amount of one - way axial load. In working conditions where axial forces are present, it can provide reliable axial positioning for the equipment. This ensures that the machinery can operate normally under complex stress environments, enhancing the stability and reliability of the overall mechanical system.

3. High - Speed Rotation Stability

The NJ306EM bearing is engineered with precision processing technologies and an optimized structural design. This enables it to maintain stable performance even at high rotational speeds. The low - friction characteristics between the rollers and the raceways, combined with the precise guidance of the cage for the rollers, effectively reduce heat generation and vibration during operation. As a result, the bearing can meet the requirements of high - speed, high - efficiency power transmission in applications such as high - speed spindles in the machine tool industry, where stable and accurate rotational performance is of great importance. The limiting speed for oil lubrication can reach up to a certain value (e.g., around 12000 - 13000 rpm in some specifications), and for grease lubrication, it can be around 8000 - 10000 rpm.

4. Excellent Fatigue Resistance

By using high - quality materials and advanced manufacturing processes, the NJ306EM bearing demonstrates excellent fatigue resistance. Under long - term full - load operation conditions, it can effectively resist failures caused by material fatigue. This significantly extends the bearing's service life, reducing the frequency of equipment maintenance and minimizing downtime. Such reliability is highly valued in industrial applications where continuous operation and high productivity are essential.

IV. Application Fields

1. Industrial Machinery

The NJ306EM bearing is widely used in various industrial machinery. In manufacturing plants, it is commonly applied in the transmission systems of automated production lines, providing stable support for high - speed and high - load rotating shafts. Its high load - carrying capacity and stability ensure the smooth operation of the production line, reducing the risk of equipment failures and improving production efficiency.

2. Power Generation Equipment

In the power generation industry, it is suitable for use in the rotor support systems of medium - sized generators and turbines. These power - generating devices operate under high - speed and high - load conditions, and the NJ306EM bearing's ability to handle large radial loads and certain axial forces, along with its high - speed rotation stability, makes it an ideal choice. It helps to ensure the safe and reliable operation of power generation equipment, contributing to the stable supply of electricity.

3. Machine Tool Industry

In the machine tool sector, the NJ306EM bearing is often used for the spindle and feed shaft support of precision machine tools. Machine tools require high precision and stability during the machining process to ensure the accuracy of the machined parts. The low - vibration and high - rigidity characteristics of the NJ306EM bearing effectively reduce spindle run - out and vibration, thereby guaranteeing the dimensional accuracy and surface quality of the machined workpieces. This, in turn, improves the overall machining efficiency and product quality in the machine tool industry.

4. Transportation Equipment

In transportation applications, such as in the axle support systems of medium - duty trucks and some construction machinery, the NJ306EM bearing plays a vital role. These vehicles and equipment operate under harsh conditions, with large loads and vibrations. The bearing's high load - carrying capacity, excellent fatigue resistance, and ability to withstand shock loads make it well - suited for these applications. It ensures the safe and reliable operation of transportation equipment, reducing maintenance costs and enhancing the overall durability of the vehicles.

V. Dimensions and Specification Parameters

VI. Maintenance Points

1. Lubrication Management

Proper lubrication is essential for maintaining the performance and extending the service life of the NJ306EM bearing. The choice of lubricant, whether grease or oil, should be based on the specific operating conditions of the equipment, including temperature, speed, and load. High - temperature extreme - pressure grease is often recommended for applications where the bearing is subjected to high loads and elevated temperatures. Before installation, it is crucial to ensure that both the bearing interior and the installation area are thoroughly clean. The appropriate filling amount of grease is typically 1/3 to 1/2 of the bearing's internal space. Regular inspections of the lubrication state should be carried out, and the lubricant should be replenished or replaced in a timely manner to maintain optimal lubrication performance.

2. Regular Inspection

Establishing a comprehensive regular inspection system is key to early detection of potential bearing problems. Visual inspections should be conducted periodically to check for any signs of cracks, rust, or abnormal wear on the bearing surfaces. Additionally, advanced monitoring tools such as vibration sensors and temperature monitors can be used to continuously monitor the bearing's operating conditions. Under normal circumstances, the bearing's working temperature should not exceed 40°C above the ambient temperature. If any abnormal increases in vibration or temperature are detected, the equipment should be immediately shut down for a thorough inspection, and necessary repairs or bearing replacements should be carried out to prevent further damage and ensure the safe operation of the machinery.

3. Installation Specifications

When installing the NJ306EM bearing, a clean installation environment must be maintained to prevent dust and impurities from entering the bearing. Specialized installation tools, such as hydraulic presses and bearing installation sleeves, should be used to ensure proper installation without causing damage to the bearing. Direct hammering on the bearing's outer or inner ring should be strictly avoided, as this can lead to bearing deformation and premature failure. During installation, it is essential to ensure that the bearing's fit with the shaft and the bearing housing meets the design requirements precisely. The interference fit should be carefully controlled within the specified range to ensure proper bearing operation and to prevent issues such as bearing slippage or over - tightening.

4. Storage Precautions

For NJ306EM bearings that are not in immediate use, proper storage conditions are crucial to maintain their quality and performance. Bearings should be stored in a dry, well - ventilated area free from corrosive gases, away from heat sources and areas with high humidity. They should be placed horizontally to avoid uneven stress and deformation caused by stacking. To prevent rusting, bearings can be wrapped in anti - rust paper or plastic film. Regular checks should be carried out during storage to ensure that the bearings remain in good condition and that their performance is not compromised over time.