Why Surface Finish in Honed Tubing Matters More Than You Think

• Ra (Roughness Average): The average of the absolute values of the surface height deviations.
• Rz: The average difference between the five highest peaks and five lowest valleys over the measured length.
• Profilometers: Stylus or optical devices that drag or scan across the surface to capture topography data.

These measurements give engineers the numbers they need to specify finishes that reduce component wear, seal abrasion, and fluid inefficiencies.

At CRC, we supply honed tubing with Ra ranges tailored to hydraulic cylinder applications, between 4-16 Ra in microinches. 

Effects of Surface Finish on Performance

Honed tubing surface finish plays a critical role in how your hydraulic system functions.

• Friction and Seal Life: Smoother surfaces reduce friction, helping seals last longer. Rough finishes increase wear and shorten lifespan.
• Fluid Flow and Efficiency: A consistent finish improves flow by minimizing turbulence inside the tubing.
• Wear, Scoring, and Fatigue: Irregular finishes create stress points that lead to scoring, fatigue, and premature wear.
• Leakage or Sealing Integrity: Too rough damages seals; too smooth reduces lubricant retention. Both can cause leaks.

How Honing Achieves a Smooth Finish

Honing is about shaping a surface that balances friction, fluid flow, and seal function. It begins with abrasive selection and stone technology. The abrasive type, grit size, and bond all influence how the metal is cut. CRC’s honed tubing uses high-precision stones for consistent finishes.

The crosshatch pattern is more than cosmetic. Its angle, typically 30° to 45°, affects both lubricant retention and seal action.

Honing parameters (feed rate, speed, and stone pressure) control how the tool shapes the surface. Faster speeds and tighter feeds yield smoother finishes, while slower settings improve dimensional control.

Post-honing treatments like polishing or chemical finishing can further reduce Ra values and enhance corrosion resistance, boosting tubing longevity.

Built for seals. Built for repair.

Industry Standards and Typical Ra Ranges

Hydraulic cylinder manufacturers often reference standards like ISO 4287 or ASME B46.1 when specifying honed tubing surface finish. 

Re-Honing Hydraulic Cylinders: Why Automation Matters

In hydraulic repair, surface finish is just as critical during rebuilds as it is in new production. Worn or scored cylinder barrels must be re-honed to restore proper seal interaction, pressure stability, and service life. Manual honing introduces variability, uneven Ra values, inconsistent crosshatch patterns, and operator-dependent results, which often show up later as premature seal wear or leakage.

Fully automated tube honing eliminates those inconsistencies by maintaining constant pressure, controlled feed rates, and uniform stroke motion across the entire bore. Automated systems deliver repeatable surface finishes, consistent crosshatch geometry, and faster cycle times while reducing scrap and operator fatigue. For repair shops, automation turns re-honing into a controlled, repeatable process that restores barrels to OEM-level performance and helps rebuilt cylinders last in real-world service.

The Bottom Line: Precision You Can Count On

Surface finish in honed tubing is a high-impact variable that influences seal action, wear rates, fluid flow, and long-term system reliability. If the inside of your tubing isn’t engineered with the right texture, your seals won’t last, your flow won’t behave, and your system won’t deliver.

CRC Distribution offers honed tubing that meets the real-world demands of high-pressure systems. With tightly controlled Ra values, precision crosshatch angles, and consistent ID tolerances, our DOM and CDS tubing sets the standard. 

Whether you're sourcing for new production or rebuilding a critical cylinder, CRC is your go-to partner for tubing that performs under pressure, and keeps performing.

Don't let a poor finish wreck your seal life.
Let's spec tubing that gets it right the first time.

FAQs

What is a typical Ra range for honed tubing for hydraulic cylinders?

Typical honed tubing surface Ra values range from 4-16 microinches.

How does surface finish affect hydraulic seal life?

A smoother inner surface reduces friction and micro‑abrasion on seals, improving their longevity and minimizing leak risks.

Can too smooth a finish be a problem?

Yes, if too smooth, lubricant retention may suffer. An optimal crosshatch pattern is as important as smoothness for hydrodynamic effects.

What tools are used to verify surface finish?

Surface finish is verified using profilometers, stylus or optical measurement systems, capturing Ra, Rz, and sometimes 3D surface data.