The installation quality of bronze bushings directly affects their service life and transmission accuracy, especially thin-walled bushings (wall thickness <5mm) are prone to deformation, cracking or abnormal fit clearance due to improper installation. The following are specific precautions and anti-deformation measures:
一. Preparation before installation (prerequisite for core anti-deformation)
1. Parts cleaning and inspection
Clean the oil, burrs and oxide scale on the inner and outer surfaces of the bushing (fine sandpaper can be used for grinding, the roughness must be ≤Ra1.6μm) to avoid scratching the mating surface during installation.
Check the bushing size tolerance: the inner hole diameter, outer diameter and length must match the design values of the shaft and seat hole (such as the bushing with interference fit, the outer diameter tolerance must meet the H7/s6 or H7/r6 standard).
Check the seat hole accuracy: the inner wall of the seat hole must be free of shrinkage holes and pores, and the cylindrical error must be ≤0.01mm/100mm, otherwise the bushing will be deformed due to uneven force.
2. Tool selection (avoid direct knocking)
Preferably use pressing tools: such as manual presses, hydraulic presses (pressure ≤50kN), or special bushing pressing blocks (made of 45 steel, end surface flatness ≤0.02mm) to ensure that the pressure acts evenly on the end face of the bushing.
It is forbidden to use a hammer to knock directly: if knocking is necessary, a copper rod (hardness ≤ HB80) must be used as a pad, and the knocking points must be evenly distributed along the circumference of the bushing (one point every 120°) to avoid excessive local force.
二. Key operations during installation (anti-deformation core)
1. Interference fit installation (most common, suitable for fixed bushings)
Preheat the seat hole (for large interference scenarios): When the interference is greater than 0.05mm, heat the seat hole to 80-120℃ (heat with a hot air gun or oil bath, heating rate ≤5℃/min), expand the seat hole and insert the bushing, and automatically hold it after cooling.
Example: A bushing with a diameter of 100mm and an interference of 0.08mm. After the seat hole is heated to 100℃, the inner diameter can expand by about 0.06mm, significantly reducing the pressure resistance and preventing the bushing from being "squeezed".
Maintain coaxiality when pressing in: When the bushing is pressed in, it needs to be positioned with a guide sleeve (optical axis with the same diameter as the shaft) to ensure that the coaxiality error between the bushing axis and the seat hole axis is ≤0.03mm, otherwise it will cause the bushing to tilt and deform (especially the bushing with a length-to-diameter ratio L/d＞2).
Press-in speed control: press-in at low speed (speed ≤5mm/s), and observe the pressure change at the same time: if the pressure suddenly increases (exceeds the calculated value by 30%), stop immediately and check whether there is any foreign matter stuck or dimensional interference.
2. Clearance fit installation (applicable to sliding bushings)
During installation, the clearance between the bushing and the seat hole must be ensured (usually 0.01-0.03mm). You can apply engine oil on the outer wall of the bushing and gently push it in by hand to avoid deformation caused by forced pressing.
If it needs to be fixed, you can drill and tap the end face of the bushing and fix it with a set screw (M4-M6) (a copper pad is required at the end of the screw to prevent scratching the bushing).
Special treatment of thin-walled bushings (wall thickness ≤3mm)
Use the segmented pressing method: for every 20mm increase in the pressing depth, pause for 10 seconds to release the stress and avoid cumulative deformation.
Apply grease (such as lithium-based grease) to the seat hole to reduce the friction coefficient and reduce the pressing resistance (the resistance can be reduced by about 40%).
三. Inspection and adjustment after installation (verification of anti-deformation effect)
1. Deformation detection
Use the inner diameter micrometer to measure the inner hole of the bushing: measure 4 points at each of the 3 axial sections (two ends and the middle), and the roundness error must be ≤0.01mm, otherwise it means that the bushing has been deformed (need to be removed and reinstalled).
Check the verticality of the end face: use a square ruler to close the end face of the bushing and the seat hole reference surface, with a clearance of ≤0.02mm to avoid local wear caused by skew.
2. Remedial measures (if slightly deformed)
For the shrinkage of the inner hole caused by interference fit, honing repair can be performed: remove 0.01-0.03mm excess and restore the inner hole size accuracy (roundness ≤0.005mm).
If there is local bulge, use a fine file (800 mesh) to repair it lightly, and then use abrasive paste (W5 particle size) to grind it manually to ensure a smooth surface without burrs.
Summary
The core principle of bronze bushing installation is **"even force, avoid impact, control precision"**: when interference fit, give priority to heating the seat hole or using a press, thin-walled bushings need to be pressed in sections and the speed must be controlled, and the inner hole roundness and end face verticality must be tested after installation. As long as these steps are strictly followed, the probability of deformation can be reduced to less than 5%, significantly extending the service life of the bushing.
Email: cast@ebcastings.com
The installation quality of bronze bushings directly affects their service life and transmission accuracy, especially thin-walled bushings (wall thickness <5mm) are prone to deformation, cracking or abnormal fit clearance due to improper installation. The following are specific precautions and anti-deformation measures:
一. Preparation before installation (prerequisite for core anti-deformation)
1. Parts cleaning and inspection
Clean the oil, burrs and oxide scale on the inner and outer surfaces of the bushing (fine sandpaper can be used for grinding, the roughness must be ≤Ra1.6μm) to avoid scratching the mating surface during installation.
Check the bushing size tolerance: the inner hole diameter, outer diameter and length must match the design values of the shaft and seat hole (such as the bushing with interference fit, the outer diameter tolerance must meet the H7/s6 or H7/r6 standard).
Check the seat hole accuracy: the inner wall of the seat hole must be free of shrinkage holes and pores, and the cylindrical error must be ≤0.01mm/100mm, otherwise the bushing will be deformed due to uneven force.
2. Tool selection (avoid direct knocking)
Preferably use pressing tools: such as manual presses, hydraulic presses (pressure ≤50kN), or special bushing pressing blocks (made of 45 steel, end surface flatness ≤0.02mm) to ensure that the pressure acts evenly on the end face of the bushing.
It is forbidden to use a hammer to knock directly: if knocking is necessary, a copper rod (hardness ≤ HB80) must be used as a pad, and the knocking points must be evenly distributed along the circumference of the bushing (one point every 120°) to avoid excessive local force.
二. Key operations during installation (anti-deformation core)
1. Interference fit installation (most common, suitable for fixed bushings)
Preheat the seat hole (for large interference scenarios): When the interference is greater than 0.05mm, heat the seat hole to 80-120℃ (heat with a hot air gun or oil bath, heating rate ≤5℃/min), expand the seat hole and insert the bushing, and automatically hold it after cooling.
Example: A bushing with a diameter of 100mm and an interference of 0.08mm. After the seat hole is heated to 100℃, the inner diameter can expand by about 0.06mm, significantly reducing the pressure resistance and preventing the bushing from being "squeezed".
Maintain coaxiality when pressing in: When the bushing is pressed in, it needs to be positioned with a guide sleeve (optical axis with the same diameter as the shaft) to ensure that the coaxiality error between the bushing axis and the seat hole axis is ≤0.03mm, otherwise it will cause the bushing to tilt and deform (especially the bushing with a length-to-diameter ratio L/d＞2).
Press-in speed control: press-in at low speed (speed ≤5mm/s), and observe the pressure change at the same time: if the pressure suddenly increases (exceeds the calculated value by 30%), stop immediately and check whether there is any foreign matter stuck or dimensional interference.
2. Clearance fit installation (applicable to sliding bushings)
During installation, the clearance between the bushing and the seat hole must be ensured (usually 0.01-0.03mm). You can apply engine oil on the outer wall of the bushing and gently push it in by hand to avoid deformation caused by forced pressing.
If it needs to be fixed, you can drill and tap the end face of the bushing and fix it with a set screw (M4-M6) (a copper pad is required at the end of the screw to prevent scratching the bushing).
Special treatment of thin-walled bushings (wall thickness ≤3mm)
Use the segmented pressing method: for every 20mm increase in the pressing depth, pause for 10 seconds to release the stress and avoid cumulative deformation.
Apply grease (such as lithium-based grease) to the seat hole to reduce the friction coefficient and reduce the pressing resistance (the resistance can be reduced by about 40%).
三. Inspection and adjustment after installation (verification of anti-deformation effect)
1. Deformation detection
Use the inner diameter micrometer to measure the inner hole of the bushing: measure 4 points at each of the 3 axial sections (two ends and the middle), and the roundness error must be ≤0.01mm, otherwise it means that the bushing has been deformed (need to be removed and reinstalled).
Check the verticality of the end face: use a square ruler to close the end face of the bushing and the seat hole reference surface, with a clearance of ≤0.02mm to avoid local wear caused by skew.
2. Remedial measures (if slightly deformed)
For the shrinkage of the inner hole caused by interference fit, honing repair can be performed: remove 0.01-0.03mm excess and restore the inner hole size accuracy (roundness ≤0.005mm).
If there is local bulge, use a fine file (800 mesh) to repair it lightly, and then use abrasive paste (W5 particle size) to grind it manually to ensure a smooth surface without burrs.
Summary
The core principle of bronze bushing installation is **"even force, avoid impact, control precision"**: when interference fit, give priority to heating the seat hole or using a press, thin-walled bushings need to be pressed in sections and the speed must be controlled, and the inner hole roundness and end face verticality must be tested after installation. As long as these steps are strictly followed, the probability of deformation can be reduced to less than 5%, significantly extending the service life of the bushing.
Email: cast@ebcastings.com
