Hydraulic motion · machined rod components
The rod carries the piston force through a sliding seal to the machine. Its steel, surface and end connections must work together—matching the outside diameter is only the start.
For chrome-plated rod stock and finished hydraulic-cylinder rods. The structure below separates the steel, its treatments and its machined features; it is not a complete cylinder assembly.
01
Fluid pressure acts on the piston inside the cylinder. The rod transmits that force to the attached load, carrying compression when pushing and tension when pulling. Repeated loading also makes the details at threads, shoulders and joints important. The chrome coating serves a different purpose at the surface where the rod moves through the sealing system. [1] [3]
| Rod structure / BOM reference | Function and material evidence | What belongs on the drawing |
|---|---|---|
| Steel rod body | Carries the axial load. Solid bar and hollow tube are distinct constructions. Ovako documents microalloyed-steel and quenched-and-tempered steel products; the selected grade and delivery condition must be identified. [2] | Finished outside diameter, any bore and wall requirement, length, grade, heat treatment and traceability. |
| Induction-hardened zone, where specified | A treated region within the steel, not an added sleeve. The IH 280X example distinguishes this zone from the base steel and the chromium above it. [2] | Hardness method, depth criterion and treated length; do not describe every chrome-plated rod as induction hardened. |
| Hard-chrome surface | The coating forms the wear and corrosion-resistant sliding surface. Thickness, surface finish and coating hardness are separate properties. [3] | Coating system, minimum thickness, finish and inspection locations; define any areas left unplated. |
| Machined ends, shoulders and transitions | Threads and fillets change the steel section and can concentrate cyclic stress. They are features of a rod unless the approved design specifies a separate attached part. [1] | Both end details, thread designation and engagement, shoulder dimensions, fillets, and joint or retention method. |
| Seal lead-in and edge transitions | A smooth entry protects the seal during assembly. Trelleborg specifies chamfers and rounded transitions, or suitable installation tooling where the rod cannot provide them. [4] | Lead-in geometry matched to the seal profile; protected thread crests and burr-free transitions. |
The rod seal retains fluid, the wiper removes external contamination as the rod retracts, and wear rings guide the moving members. These cylinder components contact or guide the rod; they are not layers of the steel rod itself. Their dimensions and materials must match the cylinder design. [5]
Ovako’s 2015 IH 280X catalogue illustrates the distinction: the 20–90 mm base-steel row lists 200–240 HB, the induction-hardened zone is at least 45 HRC, and the chrome is at least 850 HV0.1. For a 50 mm rod, its listed hardening depth is 1.0–3.0 mm, measured to the stated 400 HV5 criterion. These are historical product-specific data, not three interchangeable tests or specifications for another supplier’s rod. [2]
ISO 18265:2013 addresses hardness conversion. Its public abstract says converted values do not replace results obtained by the proper test method. Specify the layer, scale and test conditions instead of converting a coating result into a claimed steel strength. [6]
02
A polished appearance does not describe the microscopic profile that carries the lubricating film. Trelleborg’s November 2025 rod-seal guidance specifies the roughness values Ra, Rz and Rz1max and a material ratio Rmr. Its Table 5 separates the moving rod surface from the seal groove and distinguishes seal-material families. [4]
| Rod mating-surface parameter | Turcon materials | Zurcon and rubber |
|---|---|---|
| Ra · µm | 0.05–0.20 | 0.10–0.40 |
| Rz · µm | 0.40–1.60 | 0.63–2.50 |
| Rz1max · µm | 0.63–2.50 | 1.00–4.00 |
These are Trelleborg’s seal-family recommendations, not a universal tolerance for all piston rods. The same page gives a broader hardware recommendation of Ra 0.1–0.3 µm; do not substitute that sentence for the table applicable to the selected seal. Alternative coatings need their own seal compatibility assessment. [4]
The catalogue also calls for a material ratio Rmr of approximately 50–70%, evaluated at a cut depth of 0.25 × Rz with its specified reference-line conditions. An Rmr percentage without those measurement conditions is incomplete. Its paired surface profiles demonstrate why a similar Rz can conceal a substantially different contact profile. [4]
Agree the surface-texture specification and measurement setup with the rod and seal suppliers. Include the traversed surface, the applicable parameters, evaluation conditions and permissible defects. Trelleborg excludes scores, scratches, pores and concentric or spiral machining marks on the relevant sealing surface. [4]
03
For a replacement, establish which surfaces locate the rod, how the piston is retained, and how the external load attaches. A rod-end bearing is a separate connection option: LDK’s hydraulic rod-end catalogue, for example, distinguishes welded-shank and threaded/locking designs. Ordering one of these bearings does not order the chrome-plated shaft. [10]
Compression brings a buckling check; repeated push–pull loading brings a fatigue check. Ovako identifies thread roots, fillets and welded connections as critical locations. A tensile-strength number alone does not establish the allowable load of the finished rod. The calculation must represent its actual section changes, joints and loading history. [1]
Installed support matters as much as free rod length. Ovako illustrates a cylinder supported at the gland and another pinned at both ends; the effective length used for buckling differs. Stroke, exposed length, overall machined length and effective buckling length should therefore be recorded separately. Its approximate mounting example is not a universal multiplier for another installation. [1]
ISO 6020-2:2015, confirmed in 2026, concerns metric mounting dimensions for compact 16 MPa cylinders. That public scope does not certify a loose rod, set its chrome thickness or establish its allowable load. [7]
04
GLIT’s current piston-rod listing provides useful stock-level information: it lists f7/g6 or customized tolerances, a minimum chrome thickness of 15 µm below 20 mm diameter and 20 µm from 20 mm upwards, and a maximum Ra of 0.2 µm. It offers normal, quenched-and-tempered and induction-hardened conditions. Those options do not identify which combination will be supplied for a particular drawing. [8]
| Parameter to specify | Why it changes the order |
|---|---|
| Finished rod diameter · mm | State the tolerance on the finished coated surface and the seal/gland fit; add inside diameter and wall requirements for a hollow rod. [2] |
| Rod length and cylinder stroke · mm | Stock cut length is not the cylinder stroke. Supply the finished drawing and extended assembly geometry. [1] |
| Hardness · named scale and test load | Identify base steel, hardened zone or coating. Include case depth where relevant. [2] [6] |
| Straightness · deviation over a stated length | Specify both the allowed deviation and gauge length. GLIT states 0.05/1000 mm; do not turn that into a guarantee for an unspecified total rod length. [8] |
| Surface texture · µm and material ratio | Use the selected seal’s rod-surface requirements and measurement conditions, including more than Ra where required. [4] |
| Coating thickness · µm | Specify coating type, minimum thickness and extent. A value without the selected substrate and process does not settle corrosion performance. [3] [8] |
| Yield strength · MPa | Record the grade, delivery condition and finished-material evidence used in the structural assessment. [1] |
| Tensile strength · MPa | Keep the material property distinct from allowable cyclic load at threads or joints. [1] |
| Operating temperature · °C | Provide fluid and ambient conditions for the whole cylinder/seal combination; a steel grade alone does not define that operating envelope. [5] |
| Material grade and delivery condition | An alloy name without its specified condition is incomplete. Identify the ordered steel standard, heat treatment and traceability documents. [2] [8] |
| Mass · kg per finished part or kg/m of stock | State which is required and whether the rod is solid or hollow. A stock figure does not include the effects of all end machining and attachments. |
GLIT’s standard-length rows overlap at exactly 30 mm diameter: one says 2–3 m for diameters up to 30 mm and another 3–8 m from 30 mm. Its chrome-hardness range does not state the Vickers test force, and the corrosion-evaluation line supplies no exposure duration or acceptance result. Ask for those details in the quotation rather than filling them in. [8]
Chenna’s hydraulic-cylinder-piston-rod page describes a hollow design but supplies no bore or wall dimension. It prints the tolerance as uppercase “ISO F7.” Preserve that unresolved notation until the supplier issues the intended shaft tolerance on the drawing; do not silently change the letter case. Its steel labels also need an agreed material specification, not an assumed equivalence. [9]
05
At receipt, compare the agreed drawing with both machined ends, shoulder positions and the full surface traversed by the seal. Match material and coating records to the delivered identification. If the contract specifies a corrosion test, retain the test method, exposure, rating and tested coating system; a standard number alone is not a test result. These are procurement checks to agree with the supplier.
During assembly, Trelleborg’s instructions call for protected thread tips, clean parts and appropriate lead-in geometry to avoid cutting the seal. Its chamfer dimensions depend on the seal profile, so a convenient generic chamfer should not replace the selected seal’s instructions. Use the cylinder maker’s service procedure and compatible assembly materials. [4]
In service, external contamination can damage the rod surface and then the sealing system, as Ovako explains. A new seal on a damaged sliding surface does not remove that surface defect. Record where scoring or corrosion occurs and have the rod, guiding and sealing arrangement assessed together; this page does not prescribe a universal polishing allowance or replacement interval. [3] [5]
06
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Required supply: chrome-plated stock / fully machined rod / rod with attached end [ ] Controlled drawing and revision; quantity [ ] Finished outside diameter/tolerance; solid or hollow; bore/wall if hollow [ ] Overall length, seal travel, cylinder stroke and extended installation drawing [ ] Steel grade, standard, delivery condition and material traceability [ ] Both end connections, threads, shoulders, fillets and joint/retention details [ ] Maximum push/pull loads, load cycle, mounting, guidance and any side load [ ] Coating system, thickness/extent, hardness method and case depth if specified [ ] Seal identity; surface-texture parameters and measurement conditions [ ] Fluid, temperature, external contamination and corrosion exposure [ ] Straightness, end-geometry inspection and agreed coating/corrosion acceptance [ ] Surface protection, packaging and cylinder-specific assembly/service requirements [ ]
Choose rod stock or a machined rod first. The companies below include rod makers and suppliers of the seals and rod-end bearings that go with the rod.
Lists finished piston rods, solid rods, hollow bars and chrome plating. Its linked hydraulic-rod page describes a hollow part without a bore or wall dimension and prints “ISO F7” for tolerance. Obtain the intended shaft fit, material condition and complete end drawing before accepting its table as the order specification.
Product scope checked 2026-10-10
Publishes rod stock in carbon, alloy and stainless grades with f7/g6 or customized tolerances and heat-treatment conditions. The listed length bands overlap at 30 mm diameter; coating hardness lacks a test force and the corrosion line lacks a test result. Specify the exact material/process combination and inspection requirements.
Product scope checked 2026-10-10
The website offers chrome-plated bars and hollow bars, induction-hardened rods and hydraulic cylinders. Its footer names both Changzhou Datong Hydraulic Machinery and Datong Hoidings. Establish which entity will manufacture and sell the ordered stock or machined rod; the Shanghai contact address alone does not locate the plant.
Product scope checked 2026-10-10
Publishes hydraulic-cylinder piston rods alongside solid, hollow and coated-stock categories. Obtain a controlled drawing and material/coating specification rather than relying on the catalogue’s broad application claims.
Product scope checked 2026-10-10
Supplies PTFE rod seals such as the bronze-filled SPNS/STR step seal energised by an O-ring, which seals the cylinder gland against the moving rod. Send the rod diameter, surface finish and pressure when ordering seals for a new rod.
Product scope checked 2026-10-10
Manufactures hydraulic rod-end bearings with welded-shank or threaded/locking connections that form the joint at the end of the rod. Specify the rod thread or weld preparation and the load.
Product scope checked 2026-10-10
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
Only if the supplied part also matches the finished drawing and approved cylinder design. Stock diameter and finish do not define the piston attachment, outer end, shoulders, stroke-related lengths or structural capacity. [1] [9]
No. In the Ovako IH 280X example, 850 HV0.1 is the chrome-layer minimum. The induction-hardened region and base steel have separately stated hardness values. Retain both the test method and the tested layer. [2] [6]
Outside diameter alone is insufficient. The changed section and its connection details need a structural review for the actual load, mounting and cycle. A hollow-bar offer is not evidence that it can replace a solid rod in an existing cylinder. [1] [2]
Sources checked 2026-10-10. Standards bodies and regulations define the requirements; manufacturer pages show published ranges for those models only. CNFX does not certify products or suppliers.
Ask for use case, specification boundaries, supplier type, and RFQ preparation information for this product.
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