Material characteristics and process analysis for customized automotive bearings
1. Material characteristics: high strength, wear resistance, and environmental adaptability
Automotive bearings need to withstand high-frequency alternating stress, centrifugal force, and complex working conditions. The material selection must meet the following core characteristics:
High carbon chromium bearing steel (mainstream choice)
Composition: carbon content of 0.95%~1.05%, chromium content of 1.40%~1.65%, such as GCr15, GCr15SiMn, etc. Advantages: High hardness and wear resistance: After heat treatment, the hardness can reach HRC61-65, and the surface contact fatigue strength is excellent. Fatigue resistance: By using processes such as vacuum degassing and electroslag remelting, the oxygen content is reduced (the lower the oxygen content, the longer the fatigue life), and non-metallic inclusions are reduced.
Dimensional stability: High hardenability, suitable for bainitic or martensitic quenching requirements of parts with different wall thicknesses.
.Application: Core components such as rolling elements and inner and outer rings account for over 40% of the annual production of bearing steel.
.Alloy steel (high-performance requirement)
Variants: Germany 100Cr6, Sweden SKF2/SKF3, USA 52100.3/52100.4, Japan SUJ2/SUJ3, etc. Improvement: By adding molybdenum (Mo) to enhance hardenability, it is suitable for bainitic quenching of ultra thick walled parts and extends their service life.
Special materials (scenario customization)
Heat resistant steel: such as 9Cr18MoV, H13, suitable for high temperature environments (such as turbocharger bearings).
. Enhanced polymer: lightweight and wear-resistant, suitable for low load scenarios such as small wind turbines, but its strength and stability need further verification. Copper alloy: Brass and other materials have high mechanical strength and corrosion resistance, making them suitable for scenarios with high corrosion resistance requirements, but the cost is relatively high.2. Manufacturing process: Precision machining and heat treatment are the core.
The manufacturing process of automotive bearings covers four major links: material pretreatment, precision machining, heat treatment, and assembly, ensuring high precision and reliability of the product.
.Material pretreatment
Forging: Processing bars or tubes into blanks, eliminating inherent metal defects, optimizing streamline distribution, and improving material utilization.
.Spheroidization annealing: Obtaining uniformly distributed fine carbide particles on the ferrite matrix, preparing the microstructure for subsequent cold working and quenching tempering.
. Precision machiningTurning machining:
Centralized process method: One equipment completes all turning processes, suitable for small batch production.
. Distributed process method: One device completes a single process, suitable for large-scale production.Grinding Processing:
Cylindrical Grinding: Precise Control of Diameter and Roundness.
. Grinding of raceway: Use oil-based coolant to ensure the accuracy of raceway dimensions. Ultra precision machining: A grinding machine coated with lubricating oil polishes the surface, reducing roughness and improving contact fatigue life.Heat treatment
Quenching: Heat the bearing ring above the critical temperature, rapidly cool it to form martensitic structure, and improve hardness.
.Tempering: eliminates quenching stress, adjusts the balance between hardness and toughness, and ensures stability under high-speed operation.
. Key point: Strictly control the temperature and cooling rate to avoid cracking or deformation.Assembly and Inspection
Parts Cleaning: Remove oil stains and impurities to prevent assembly contamination.
.Fitting and clearance adjustment: Group and select according to the size of the inner and outer rings, and control the axial clearance.
. Retainer riveting: Ensure that the steel ball rotates flexibly and does not fall off in the pocket hole. Final inspection: Testing nominal height, rotational flexibility, and dust resistance. Rust prevention and packaging: Apply rust prevention oil, package and store.III. Process Optimization under Customization Requirements
For different application scenarios, the customization of automotive bearings requires precise matching of materials and processes:
High load scenarios (such as heavy-duty trucks)
Material: High hardenability alloy steel (such as GCr15SiMn) is selected to enhance impact resistance.
.Process: Optimize forging streamline distribution, enhance material density;
; Adopting bainitic quenching to enhance toughness.High speed scenarios (such as electric drive systems for new energy vehicles)
Material: low oxygen content high carbon chromium steel, reducing fatigue crack sources.
.Process: Precision grinding reduces surface roughness;
; Ultra precision machining enhances contact fatigue life.Corrosion resistant scenarios (such as vehicles in coastal areas)
Material: copper alloy or stainless steel, enhancing corrosion resistance.
.Process: Surface coating treatment to enhance protective performance.
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