The core impact of bushing material properties on performance
The material properties of the bushing is the essential factor to determine its performance, different characteristics through the mechanical, physical, chemical and other dimensions directly affect the equipment's load carrying capacity, wear resistance life, environmental adaptability and other key indicators. The following six core characteristics from the start, analyze the material characteristics and the performance of the sleeve of the intrinsic correlation:
First, hardness: wear resistance and deformation resistance of the determining factor
Characteristics of the mechanism: material hardness (such as HRC, HB and other indicators) directly determine the surface resistance to wear. The higher the hardness, the greater the ability of the material surface to resist particle scratching and adhesive wear. For example, GCr15 bearing steel hardened to HRC61-65 has a wear life 8-10 times that of 45# steel (HB170-217).
Second, strength and toughness: the double guarantee of load bearing capacity
Tensile strength and yield strength: determine the ability of the bushing to resist fracture and plastic deformation. For example, the yield strength of 20CrMnTi alloy steel is more than 850MPa after carburizing treatment, which is suitable for heavy load scenarios such as automobile gearboxes (to withstand torque of more than 3000N・m).
Impact toughness: measures the ability of a material to resist sudden loads. Tin bronze bushings (impact toughness ≥ 30J/cm²) are less likely to crack in the start-stop shock of a ship's propulsion system, while high-hardness bearing steels (lower toughness) are more suitable for steady load conditions. Tin bronze bushings (impact toughness ≥ 30J/cm²) are less likely to crack in the start-stop shock of a ship's propulsion system, while high-hardness bearing steels (lower toughness) are more suitable for steady load conditions.
Performance correlation:
Insufficiently strong bushings can fracture during overload (e.g. crane transmission bushings fracture leading to safety accidents).
The balance of toughness and strength to determine the adaptability of the bushing conditions, such as construction machinery bushing need to have both 600MPa tensile strength and ≥ 25J/cm² of impact toughness.
Third, corrosion resistance: the core indicators of environmental adaptability
Impact on performance:
In food machinery, 304 stainless steel bushing avoids rust and corrosion contamination of raw materials, in line with FDA health standards.
In marine engineering, the sleeve with insufficient corrosion resistance will produce holes due to electrochemical corrosion, resulting in failure of the ship's transom seal.
Fourth, thermal conductivity and coefficient of thermal expansion: the key to temperature stability
Thermal conductivity: copper alloy (thermal conductivity 370W/(m・K)) than carbon steel (45W/(m・K)) is 8 times higher than the high-speed operation of the equipment (eg, motor rotor bushings) in the friction can quickly dissipate the heat to control the operating temperature at 120 ℃ or less, to avoid the lubricating grease carbonization.
Thermal expansion matching: The difference between the coefficient of thermal expansion of the bushing and the shaft can lead to thermal assembly failure. For example, aluminum alloy bushing (coefficient of thermal expansion 23 × 10-⁶ / ℃) and steel shaft (12 × 10-⁶ / ℃) in the high temperature environment (> 200 ℃) will be due to the difference in the expansion of the gap, affecting the rotational accuracy.
Five, friction reduction and self-lubrication: friction power control factors
material microstructure impact: tin bronze in the lead particles (such as ZCuSn10Pb1 containing 3% lead) in the friction surface to form a solid lubrication film, the coefficient of friction can be reduced to 0.08 (carbon steel dry friction coefficient of 0.6), suitable for poor lubrication conditions (such as agricultural machinery is not regularly maintained scenarios).
Performance correlation: poor friction reduction bushings will lead to increased energy consumption of equipment, such as ordinary carbon steel bushings in the absence of lubrication conditions, power consumption than the copper alloy bushings more than 30% higher, and prone to occlusion embrace.
Sixth, processing performance and dimensional stability: manufacturing accuracy and long-term reliability of the basis
Cutting processability: 45 # steel (cutting performance index 100%) than stainless steel (45%) is easier to process, suitable for mass production; and GCr15 bearing steel needs to be ground through the grinding process (surface roughness Ra ≤ 0.8 μm) in order to achieve the requirements of precision fit.
Heat treatment stability: bearing steel after deep cold treatment of dimensional changes of ≤ ± 0.002mm, to ensure that precision machine tool spindle bushings in long-term use to maintain μm-level accuracy, while the material is not stabilized by the release of stress will lead to precision drift.
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