Forged Piston Rods
A piston rod reverses direction thousands of times an hour under alternating tension and compression, while a seal runs continuously along its surface.
Forged piston rods carry alternating tension and compression thousands of times per hour while a seal runs continuously along their surface. Forged grain running along the axis resists that reversed loading, with ground and chrome plated surfaces to Ra 0.4 µm for seal life.
- Diameter
- 20 mm – 200 mm
- Length
- Up to 2,000 mm
- Materials
- EN8, EN19, CK45, 42CrMo4
- Surface
- Ground, chrome plated
- Finish
- Ra 0.4 µm or better
Forged Piston Rods at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Diameters 20 mm to 200 mm
- Lengths up to 2,000 mm
- Ground to Ra 0.4 µm or better
- Hard chrome plating through qualified partners
Alternating Load and Buckling
The rod is pulled and pushed alternately, so fatigue governs, and in compression it can buckle if slenderness is too high. Forged material with continuous grain along the axis carries that reversed loading far better than bar stock with cut fibre at the ends.
- Alternating tension and compression
- Buckling limit in compression
- Grain continuous along the axis
- Threaded ends critical
Surface Quality for Seal Life
The seal runs on the rod surface continuously. Surface finish, hardness and straightness determine seal life more than the seal itself does, which is why rods are ground and, where specified, hard chrome plated.
Piston Rod Capability
A piston rod reverses direction thousands of times an hour under alternating tension and compression, while a seal runs continuously along its surface. Fatigue governs the design, and in compression the rod can buckle if slenderness is too high.
| Parameter | Range |
|---|---|
| Diameter | 20 mm – 200 mm |
| Length | Up to 2,000 mm |
| Materials | EN8, EN19, CK45, 42CrMo4 |
| Surface | Ground, chrome plated through qualified partners |
| Finish | Ra 0.4 µm or better |
Where Piston Rods Fail
Three failure modes account for most cases: fatigue at threaded ends or shoulder transitions where stress concentrates; buckling in compression on slender rods; and seal leakage caused by surface damage, corrosion pitting or straightness outside tolerance. Threaded ends deserve particular attention because they combine a stress concentration with the highest tensile load in the assembly.
People also ask
What causes piston rod seal leakage?
Surface damage, corrosion pitting, insufficient surface finish, or rod straightness outside tolerance causing the seal to run eccentrically.
Should piston rods be chrome plated?
For hydraulic service, almost always — chrome plating provides corrosion resistance and a hard, smooth surface for the seal. Compressor rods may use other treatments.
What lengths can you produce?
Up to 2,000 mm in diameters from 20 mm to 200 mm.
Topics covered on this page
- piston rod
- cylinder rod
- buckling
- seal surface
- hard chrome plating
- reversed loading
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
Why do piston rods fail?
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Fatigue at threaded ends or shoulder transitions, buckling in compression if too slender, and seal damage from surface defects or corrosion.
Are rods chrome plated?
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Grinding is done in-house; hard chrome plating is completed through qualified partner processors with certificates.
What surface finish is required for seals?
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Ra 0.4 µm or better, since seal life depends directly on the surface running against it.