Custom Hydraulic Cylinder: Clevis-Mounted, Solid Forged Piston Rod
Double-acting hydraulic cylinder with clevis mounting on both ends. Bore 110 mm, rod 60 mm, stroke 807 mm, working pressure 350 bar. Material: E355 seamless steel tube (EN 10297-1) and C45 hard chrome-plated solid forged piston rod (EN 10083-2). Coating: RAL 7004 Signal Grey. Full manufacturing cycle with pressure testing at 525 bar.
Material
| Standard | Grade |
|---|---|
| EN 10297-1 | E355 (≈ DIN St52) |
| EN 10083-2 | C45 / 1.0503 (AISI 1045) |
The cylinder tube is manufactured from E355 seamless steel — a medium-carbon, low-alloy structural steel with a minimum yield strength of 355 MPa and tensile strength in the range of 490–630 MPa. This grade provides an excellent combination of strength, weldability, and machinability, making it a standard choice for hydraulic cylinder bodies operating at pressures up to 350 bar.
The piston rod is manufactured from C45 medium-carbon steel (EN 10083-2 / AISI 1045). The rod blanks are produced by open-die forging to form the integral clevis ends, followed by CNC turning and hard chrome plating.
Cylinder tube chemical composition (heat analysis, EN 10297-1 E355):
C ≤ 0.22 %, Si ≤ 0.55 %, Mn ≤ 1.60 %, P ≤ 0.025 %, S ≤ 0.025 %
Dimensions
| Parameter | Value |
|---|---|
| Bore diameter | 110 mm |
| Rod diameter | 60 mm |
| Stroke | 807 mm |
| Port connections | G 1/2″ |
| Mounting | Clevis (both ends) |
Hydraulic Parameters
| Parameter | Value |
|---|---|
| Working pressure | 350 bar |
| Test pressure | 525 bar |
| Oil flow max | 220 l/min |
| Cylinder type | Double-acting |
| Mounting | Double clevis |
The cylinder is designed with a 2.1× safety factor between working and test pressure.
Sealing System
The sealing arrangement includes piston T-seals, rod U-seals, O-rings with back-up rings, guide rings, and a wiper ring. All elastomeric seals are manufactured from NBR (nitrile rubber) rated for the operating pressure and temperature range. Compatible sealant brands: Hallite, Merkel, Parker, Trelleborg.
Hard Chrome Plating
| Parameter | Value |
|---|---|
| Rod material | C45 (EN 10083-2) |
| Chrome layer thickness | ≥ 25 μm |
| Chrome hardness | ≈ HV 850–1050 |
The piston rod receives hard chrome plating after final machining. The chrome layer provides a low-friction, corrosion-resistant surface for the rod seal interface. The minimum coating thickness of 25 μm ensures adequate service life in industrial hydraulic applications.
Surface Coating
| Layer | Minimum thickness |
|---|---|
| Primer | 100 μm |
| Topcoat (RAL 7004) | 50 μm |
| Total | 150 μm |
The cylinder body is coated with a two-layer paint system in RAL 7004 (Signal Grey). The coating provides corrosion protection suitable for both indoor and outdoor installations. Mounting clevises, rod surface, and port threads are masked during painting.
Production Process
Material Procurement and Incoming Inspection
Stage 1
Raw materials were procured with EN 10204 Type 3.1 mill test certificates: seamless steel tube (E355), round bar stock (C45), and forging blanks. Incoming inspection verified chemical composition, mechanical properties, and dimensional compliance.Forging of Piston Rod Ends
Stage 2
The piston rod clevis ends were produced by open-die forging from C45 round bar stock. Each rod blank was heated and forged into the required clevis profile, forming an integral one-piece rod-and-eye assembly — eliminating the need for welded rod end attachments.Forging of Piston Rod Ends
CNC Machining
Stage 3
All cylinder components were machined on CNC lathes and machining centres:
- Cylinder tube: boring, honing to H8 tolerance on the bore surface
- Piston: turning with seal grooves for T-seal and guide ring
- Piston rod: turning to f7 tolerance, threading, machining of forged clevis ends
- Gland (cylinder head): turning with precision bore for rod seal housing, external threading
- Cylinder eyes: milling and boring of base-end clevis mounting brackets
- End caps and flanges: turning, threading
Welding
Stage 4
The base-end clevis brackets were welded to the cylinder tube. Weld quality was verified by visual inspection and dimensional checks of the completed weldments.Welding
Hard Chrome Plating
Stage 5
Each piston rod was hard chrome plated with a minimum coating thickness of 25 μm. After plating, the rod surface was ground and polished to achieve the required surface finish for reliable seal performance.Painting, Assembly, and Testing
Stage 6
The cylinder body, clevises, and end caps were coated with primer (100+ μm) and RAL 7004 topcoat (50+ μm), total dry film thickness exceeding 150 μm. After drying, all components were assembled with the specified sealing elements. Thread-locking adhesive was applied to the gland threads. Each assembled cylinder was pressure-tested at 525 bar and held under pressure. The test verified zero external leakage, stable pressure holding, and smooth rod extension/retraction.Painting, Assembly, and Testing
Marking, Final Inspection, and Packaging
Stage 7
Each cylinder was engraved with a unique serial number, month, and year of manufacture. Final dimensional and visual inspection was completed. Cylinders were wrapped in protective film and packed into wooden crates with internal padding.
Standards Reference
| Domain | Standard |
|---|---|
| Cylinder tube material | EN 10297-1: E355 |
| Piston rod material | EN 10083-2: C45 / 1.0503 |
| Material certificates | EN 10204 Type 3.1 |
| General tolerances | ISO 2768-mK |
| Surface preparation | ISO 8501-1 Sa 2.5 |
| Colour | RAL 7004 Signal Grey |
