A cylinder flange is a discshaped part used to mount the hydraulic cylinder to the machine frame or connect the cylinder barrel to the end cap. It bears axial force and ensures alignment and sealing.

Common Types

1. Front flange (head flange)
2. Rear flange (cap flange)
3. Round flange / square flange
4. Welded flange
5. Threaded flange

Typical Materials

1. 45# carbon steel (most common)
2. 40Cr alloy steel (high pressure & heavy load)
3. Ductile iron
4. Aluminum alloy (lightduty cylinders)

Basic Machining Process

1. Sawing: Cut bar/forging to length
2. Rough turning: Face both ends, turn OD and ID
3. Finish turning: Machine bore (for barrel fit), spigot, end faces
4. Milling / drilling: Drill mounting bolt holes, drill ports if needed
5. Chamfering & deburring
6. Welding or assembly (if welded to tube)
7. Stress relieving & surface treatment (blackening, painting, etc.)

Key Tolerances

1. Bore for cylinder tube: H7/h7 or H8/h7
2. Bolt hole position tolerance: ≤ 0.1 mm
3. Face flatness: ≤ 0.02 mm
4. Surface roughness:
   • Sealing faces: Ra ≤ 1.6 μm
   • Mounting faces: Ra ≤ 3.2 μm
5. Concentricity between ID and mounting face: high precision required

Machining Notes

1. Ensure high concentricity to avoid binding or leakage.
2. Bolt holes must be accurately positioned and evenly spaced.
3. All sharp edges must be chamfered to protect seals.
4. Welded flanges need groove preparation and stress relief to prevent deformation.