Honed vs Non-Honed Hydraulic Cylinder Tubes: Condition and Selection

Honed vs non-honed hydraulic cylinder tubes is primarily a comparison of supplied bore condition. Honing is an abrasive bore-finishing process used to control geometry and texture. A non-honed tube may be stock intended for later finishing, or it may have another approved finished bore. The label alone does not establish whether a tube is ready for a particular cylinder design.

For engineers and buyers, define the finished bore and seal requirements first, then choose the manufacturing and delivery sequence. A smooth-looking bore is not automatically a suitable sealing surface, and a honed tube is not automatically approved for pressure, fatigue or the complete cylinder assembly.

Key takeaway: specify bore size, shape, surface profile, cleanliness and material condition. Clarify whether the delivered tube is finished or includes stock allowance for the customer’s later operation.

What honing changes in a cylinder tube

Sunnen’s honing process explanation describes abrasive material removal used to achieve bore geometry and surface finish. Honing is a machining operation, not a steel grade or a heat-treatment designation. The starting condition and the required finished result determine the appropriate stock removal.

The process may address small geometric deviations and establish a specified surface texture, but it cannot be assumed to correct any amount of bow, eccentricity, wall variation or deep damage. The processor must assess the starting bore and the available allowance. Removing more material also changes the remaining wall.

Do not confuse honing with polishing only the visible end. A full-length cylinder bore must satisfy the requirements over the relevant working region. Measurement should establish the actual geometry and texture rather than relying on a bright appearance.

Compare delivered conditions, not just process names

Offered condition	Likely purchase purpose	Questions to resolve
Honed to a specified finished bore	Use in the agreed next assembly/fabrication stage	Does the full bore meet size, geometry, texture and cleanliness requirements?
Non-honed stock for later honing	Customer or subcontractor performs final finishing	Is allowance sufficient and controlled for complete cleanup?
Skived/roller-burnished or another finished route	Alternative approved bore-finishing process	Does the resulting geometry and profile suit the actual sealing system?
Undefined smooth bore	Insufficient description for engineering acceptance	Which measurable requirements and process evidence are missing?

Sunnen distinguishes honing and skiving/roller burnishing as different bore-processing routes. Do not treat them as identical operations. Either route must be evaluated against the final cylinder requirements, rather than accepted because a supplier uses the word precision.

For upstream tube choices, see the hydraulic tube selection guide. Keep cylinder barrel requirements separate from the requirements for small-bore hydraulic lines.

Specify a surface that works with the seal

Sealing behavior depends on the interaction of the seal, fluid, operating conditions and counter surface. The Trelleborg counter-surface discussion explains why this is a tribological system rather than a contest for the smallest roughness number.

A very low Ra value does not alone describe the profile, valley structure or material contact characteristics relevant to a selected seal. Conversely, a visible crosshatch does not demonstrate that the profile is acceptable. Follow the actual seal manufacturer’s current recommendations and the approved drawing.

State the required roughness or profile parameters and their evaluation method, along with measurement location and direction. Do not copy a generic Ra range from a different seal material or service. The surface Ra guide can support the discussion, but the seal/application specification remains controlling.

Bore geometry and remaining wall remain separate checks

Define bore diameter, roundness, cylindricity, straightness or other necessary geometric relationships using the drawing’s datums. A local bore measurement near one end does not establish the full working length. The number and location of measurements should represent the feature being accepted.

If final machining removes material from the bore, review the resulting minimum wall and its relationship to the outside surface. Starting OD and nominal wall cannot simply be carried forward unchanged. The dimensional accuracy guide helps separate these geometric characteristics.

For a tube supplied with honing allowance, define which bore dimensions apply before finishing and which apply afterward. Too little allowance can leave incomplete cleanup; excessive or inconsistent allowance can increase processing and jeopardize the intended remaining section. The processor should establish a feasible range for the actual starting stock.

Choose the process sequence before ordering

Ports, end features, joining and thermal processing may influence the final bore. Decide where honing or another finishing operation sits in the complete route. If the tube is honed before an operation that distorts or contaminates it, the finished surface may need another assessment.

Document whether the customer will bore, hone, weld, wash or otherwise process the delivered tube. The supplier’s delivery acceptance should match that agreed stage. A semi-finished product should not be labeled ready for assembly unless the relevant requirements are met.

Maintain identity through subcontract finishing. The traceability guide explains why cutting and processing records must remain linked to the supplied material.

Clean and protect the finished bore

Honing produces material and abrasive residues that need an appropriate cleaning process. Define the cleanliness requirement, test method and protection after cleaning. A quick visual inspection or wiping the accessible end does not necessarily establish the condition of the full bore.

Protect the finished surface against corrosion and handling damage using a compatible agreed preservation method. End caps help prevent recontamination but do not prove that the required cleaning was done. Packaging, storage assumptions and removal of protective films should be part of the order.

A cylinder-tube finish specification checklist

1. Material standard, grade, supplied condition and manufacturing-route restrictions.
2. Finished bore size and functional geometric requirements.
3. Seal-specific texture/profile requirements and measurement method.
4. Stock allowance if the bore will be finished after delivery.
5. Remaining-wall requirement after all machining.
6. Ports, joining, thermal processing and final inspection sequence.
7. Cleaning, preservation, end protection and traceability.
8. Any required component validation, separate from bore-finish acceptance.

Common questions

Is honed tube always better than non-honed tube?

No. Non-honed stock may be the right choice when the customer will establish the final bore after other processing. The correct choice is the delivery condition that supports the approved sequence and finished requirements.

Can a non-honed bore be ready for seals?

Possibly, if another approved process produces the required geometry, texture and cleanliness. Verify the actual measured result and the sealing-system requirements. Do not accept an undefined smooth-bore description as proof.

Does honing increase the pressure rating?

Honing is not a pressure-rating approval and removes material. The cylinder’s pressure capability depends on the complete design, material, remaining section, joining and applicable rules. The responsible engineer must verify those requirements separately.

Order the bore condition your process needs

When discussing honed or non-honed cylinder tubes with Tenjan, supply the bore drawing, seal requirements and complete fabrication sequence. Request a clear statement of the delivered condition and any finishing allowance. This makes a process label into a measurable, usable product requirement.