67,68,69 Series Thin Bearings

AUBEARING manufactures standard thin-section bearings in the 6700, 6800, and 6900 series using 52100 chrome steel. Upon request, stainless steel series and hybrid ceramic series are also available.

Stainless Steel Series

Compared to chrome steel, stainless steel offers lower noise, lower friction torque, and corrosion resistance. Bearing rings and rolling elements are made from AISI SUS440C and undergo vacuum catalysis treatment. Cage and seal skeleton materials are typically made from AISI 304 stainless steel. Stainless steel bearings have enhanced rust and corrosion resistance, and with appropriate lubricants and dust covers, they can operate in environments ranging from -60°C to +300°C. Due to their high mechanical strength and load capacity, stainless steel thin-section bearings are widely used in food processing, medical devices, and pharmaceutical machinery.

Hybrid Ceramic Series

Hybrid ceramic bearings generally feature stainless steel rings and ceramic balls (ZrO2, Si3N4, or SiC). Silicon nitride balls have low density, high hardness, low friction coefficient, magnetic and electrical insulation, excellent wear resistance, self-lubrication, good rigidity, superior acid resistance, and can withstand high temperatures above 300°C. They significantly reduce rolling friction and heat generation, with a lifespan three to five times longer than steel bearings, and are 60% lighter than steel. The elastic modulus of ceramic balls is 50% higher than that of steel, making them ideal for high-speed, high-precision, and long-life applications. Si3N4, with its comprehensive superior performance, has become the preferred material for hybrid ceramic bearings.

Lubrication

Open series bearings use lubricating oil (with viscosity between 0.12 and 0.2 cm/s) to achieve excellent cooling effects, particularly suitable for applications with high working temperatures. For high-load, high-temperature bearings, high-viscosity lubricating oil is required. Additionally, a complex oil supply system must be considered.

Sealed or shielded thin-section bearings use grease lubrication. Grease has a very low evaporation rate, providing long-term lubrication in high-speed and high-temperature operations, reducing bearing maintenance frequency. Grease has better adhesion, allowing it to stick well to the lubricated surfaces of the bearing, achieving better lubrication.

AUBEARING Thin-section Bearing Manufacturing Steps

Material Selection and Preparation: The manufacturing of thin-section bearings begins with material selection. High-quality raw materials are the foundation of high-quality bearings. Bearing materials typically require high hardness, high strength, high wear resistance, and good toughness. Common materials include chrome steel, stainless steel, ceramics, etc. During the material preparation phase, strict chemical composition analysis and physical performance testing are required to ensure they meet manufacturing requirements.

Forging: Forging is a critical step in bearing manufacturing. First, high-carbon chrome steel (or stainless steel) is pretreated and heated to above 1000°C, then precisely die-pressed to form the dimensions and shapes required for the bearing. Forging improves material density and strength, eliminates casting defects, and enhances product quality.

Heat Treatment Process: Heat treatment is a key step in bearing manufacturing. Through heat treatment, the structure and performance of the material are improved, enhancing bearing hardness, wear resistance, and fatigue strength. Common heat treatment processes include quenching, tempering, and carburizing. These processes require precise control of heating temperature, holding time, and cooling rate to achieve the desired material properties.

CNC Machining: CNC machining is the core process in the manufacture of thin-walled ball bearings. This process includes turning, milling, and grinding, aiming to process raw materials into bearing parts with specific shapes and sizes. High-precision machine tools and cutting tools are required to ensure the dimensional accuracy and shape precision of critical parts such as inner and outer rings and rolling elements. Temperature and force during machining must also be controlled to avoid excessive stress and deformation.

Assembly: Assembly is the final steps in bearing manufacturing. During assembly, parts must be assembled according to strict process requirements to ensure the assembly precision and reliability of the bearing. The tuning stage involves performance testing and adjustment of the bearing. Testing bearing rotational flexibility, friction torque, and other indicators determine if the bearing meets design requirements. Bearings that do not meet requirements need adjustment or reprocessing until they meet standards.

Quality Control and Testing: Quality control and testing are critical to ensuring bearing quality. From raw material inspection to real-time process monitoring and final product inspection, strict quality control is necessary. Common testing methods include dimensional measurement, hardness testing, and metallographic analysis. These methods comprehensively evaluate bearing performance and quality to ensure they meet design requirements and usage standards.

It is noteworthy that the internal clearance (radial clearance) of thin-section bearings can reduce interference fit by up to 80%. The 6900 series thin-section bearings can handle heavy loads, while the 6700 and 6800 series can only bear lighter loads.