Manufacturing Process of Slewing Bearings

Slewing bearings, as crucial components in numerous mechanical equipments, have a complex and intricate manufacturing process. This process involves multiple key steps, and each step significantly impacts the quality and performance of the final product.

What is Slewing Bearing?

The slewing bearing is a large – scale bearing capable of withstanding comprehensive loads. It is used to support and connect mechanical components that need to rotate relative to each other. It typically consists of an inner ring, an outer ring, rolling elements, and a cage. Slewing bearings can simultaneously bear axial forces, radial forces, and overturning moments, and are widely applied in large – scale mechanical equipments such as cranes, excavators, wind turbines, and port machinery. Its function is to enable the rotating parts of the equipment to rotate stably and flexibly, ensuring the normal operation of the equipment, improving its working efficiency and reliability. It is an indispensable key component in many large – scale machines.

Raw Material Procurement and Inspection

The quality of raw materials serves as the foundation for the performance of slewing bearings. The main raw materials include high – quality steel, such as medium – carbon alloy steel, which is used to manufacture key components like inner and outer rings, as well as steel for rolling elements (steel balls or rollers). When purchasing, it is necessary to carefully screen suppliers to ensure that the materials meet national standards and design requirements. After the arrival of the goods, conduct a comprehensive inspection of the raw materials. Use spectral analysis to detect chemical components, evaluate mechanical properties through hardness tests and tensile tests, and check for internal and surface defects using ultrasonic flaw detection and magnetic particle flaw detection. Only raw materials with qualified indicators can enter the production process.

Part Machining of Slewing Bearings

Inner and Outer Ring Machining

Firstly, cut the steel to obtain blanks of appropriate sizes. In the rough turning process, remove most of the allowance, leaving a machining allowance of 0.5 – 1 mm for subsequent finish machining to improve processing efficiency. Finish turning ensures the dimensional accuracy and surface roughness of the inner and outer rings. The dimensional tolerance of the raceway part is controlled within ±0.01 mm, and the surface roughness reaches Ra0.8 – Ra1.6μm. In the milling process, machine structures such as mounting holes and keyways to ensure position accuracy. After the processing is completed, measure the dimensional accuracy again to ensure compliance with the design drawings.

Rolling Element Machining

If steel balls are used, process the steel into spherical blanks, and through processes such as rough grinding, fine grinding, and lapping, gradually improve the dimensional accuracy and surface quality of the steel balls, and control the roundness error within a very small range. The machining of rollers includes turning the outer circle, grinding, and lapping to ensure the cylindricity and surface roughness of the rollers and ensure smooth rolling within the raceway.

Cage Machining

Manufacture the cage by stamping, injection molding, or machining according to design requirements. Stamped cages are suitable for mass production with high efficiency; injection – molded cages have low costs and light weights; machined cages have high precision. After processing, check the dimensional accuracy, structural integrity, and surface quality of the cage to ensure that it can evenly separate the rolling elements and reduce friction and wear between the rolling elements.

Heat Treatment of Slewing Bearings

Quenching and Tempering

Inner rings, outer rings, and rolling elements need to undergo heat treatment after machining. Quenching can improve the hardness and strength of the material. Heat the parts to an appropriate temperature, hold for a certain period of time, and then cool rapidly. Tempering relieves the internal stress generated during quenching and adjusts hardness and toughness. Heat the quenched parts to a range lower than the quenching temperature, hold, and then cool. Through appropriate quenching and tempering processes, the comprehensive mechanical properties of the parts reach the optimal state.

Surface Treatment

To improve the wear resistance, corrosion resistance, and fatigue life of slewing bearings, surface treatment is often carried out. For example, use chemical heat treatment methods such as carburizing and nitriding to form a high – hardness hardened layer on the surface of the parts; or perform surface coating treatments such as electroplating and spraying to cover a protective film on the surface of the parts.

Assembly of Slewing Bearings

Cleaning and Inspection

Before assembly, thoroughly clean all parts to remove impurities such as oil stains and iron filings remaining during the machining process. After cleaning, check the dimensional accuracy, surface quality, and appearance of the parts again to ensure there are no defects or damages.

Assembly Process

First, fix the inner ring on the assembly platform, install the cage, and then install the rolling elements between the cage and the inner ring according to the specified quantity and interval. When installing the outer ring, ensure the fitting accuracy between the outer ring, the inner ring, and the rolling elements, and control the clearance within a reasonable range. If the clearance is too large, it will lead to a decrease in rotational accuracy and an increase in vibration; if the clearance is too small, it will increase friction and wear, and may even cause parts to seize. During the assembly process, use special tools and equipment to ensure assembly accuracy.

Pre – tensioning and Adjustment

Some slewing bearings need to be pre – tensioned. By applying a certain axial or radial force, the clearance is eliminated to improve rotational accuracy and rigidity. After pre – tensioning, test and adjust the rotational flexibility, radial and axial run – out, and other performances of the slewing bearing to ensure compliance with design requirements.

Quality Inspection of Slewing Bearings

Appearance Inspection

Inspect the appearance of the slewing bearing to ensure that there are no defects such as cracks, blowholes, and pores on the surface, and that the paint coating is uniform and free from peeling.

Dimensional Accuracy Detection

Use measuring tools to detect the diameters, widths, raceway sizes of the inner and outer rings, as well as the positions and sizes of the mounting holes, etc., to ensure compliance with the tolerance requirements of the design drawings.

Performance Testing

Carry out rotational flexibility tests to check whether the rotation process is smooth and free from jamming; measure radial and axial run – out to evaluate rotational accuracy; conduct loading tests to detect the bearing capacity and fatigue life of the slewing bearing, ensuring reliable performance in actual use.

Prices of Slewing Bearings

There are many factors affecting the prices of slewing bearings. Firstly, raw materials play a significant role. High – quality steel has a high cost, and products made from it have excellent performance and long service life, thus commanding a high price. Secondly, slewing bearings with complex manufacturing processes and high – precision requirements require advanced equipment and strict quality control, which also leads to an increase in price. Moreover, the larger and more special the size and specifications are, the greater the processing difficulty and material consumption, and the higher the price will be.

Suppliers of Slewing Bearings

The products of Ldb bearing company cover a wide range. Whether they are standard – sized or non – standard slewing bearings, the company can produce them with high quality to meet the diverse needs of different customers. Its products are widely used in multiple fields, demonstrating its strong capabilities.