Honed Tubes Explained: Tolerances, Surface Finish and Where to Use Them
Ready-to-honed, SRB, ground — what each one means, how the tolerances stack up, and how to spec the right tube for your hydraulic cylinder.
Cylinder makers ask us for "honed tube" — but the term covers at least three distinct manufacturing processes with very different price points and tolerances. Knowing which one you need can save 20–30% on material cost.
The three common types
Cold-drawn seamless (CDS)
The cheapest option — drawn to a tight outside diameter but the inside is left in the drawn condition. Surface finish is typically Ra 1.6–3.2 µm and the bore is not concentric to the OD. Suitable only as a pre-form before in-house honing.
Skived & roller-burnished (SRB) — "ready to honed"
After cold-drawing, the inside is mechanically skived to remove scale, then a hardened roller is pressed against the bore to compact the surface. Result: Ra 0.2–0.4 µm, bore-to-OD concentricity around 0.15 mm, and a hardened skin layer that improves seal life. This is what most Indian cylinder makers actually mean when they say "honed tube".
Ground & honed
The premium choice. After SRB, the bore is fine-honed to Ra 0.1–0.2 µm with H8 or H9 diameter tolerance. Used for servo-hydraulic actuators, test rigs, and aerospace ground support equipment where seal life and stiction matter.
How to spec a tube on your PO
- State the standard (e.g. DIN 2391 / ST52 BK+S)
- State the bore tolerance band (H8, H9, or H10)
- State the maximum Ra and acceptable bore-to-OD concentricity
- State the length tolerance and end-prep (square cut, deburred, chamfered)
- Ask for material test certificate (MTC) per EN 10204 type 3.1 or 3.2
For most general-industry hydraulic cylinders up to 250 bar, SRB tube in ST52 / E355 with H9 bore is the sweet spot — performance close to ground tube at roughly half the cost.
Common application bands
- Construction equipment (excavator boom rams, loader cylinders) — SRB, ST52, H9
- Industrial presses & injection moulding — Ground & honed, ST52 or 27SiMn, H8
- Hydraulic test rigs & servo actuators — Ground & honed, custom chrome plating
- Agricultural cylinders — SRB, E235 or E355, H10 (cost-sensitive)
If you are unsure which grade fits your cylinder, send us the drawing on WhatsApp — we will mark up the spec and quote both an SRB and a ground option so you can compare cost-to-life.
