Two routes to the same diameter
Skiving and roller burnishing, usually shortened to SRB, and honing both finish the inside of a tube to a tolerance and a surface finish. They get there by different mechanisms, and the bore they leave behind is not the same even when the diameter gauge and the roughness meter read identical numbers.
Honing is abrasion. Stones press against the wall while the tool rotates and reciprocates, cutting material away and correcting the form of the bore as it goes. Skiving is cutting. A carbide head shaves a thin chip from the wall in a single pass, and rollers trailing behind it cold-work the freshly cut surface, pressing the peaks into the valleys.
What that difference leaves on the wall
| Attribute | Honing | Skiving and roller burnishing |
|---|---|---|
| Material removal | Abrasive, multi-pass, self-correcting for form | Single-pass cutting, form follows the preceding bore more closely |
| Surface pattern | Cross-hatch diamond pattern, controlled angle | Smoother, burnished, less pronounced groove structure |
| Surface hardness | Little change to the parent metal | Cold working raises surface hardness |
| Compressive residual stress | Low | High, introduced by the rollers |
| Length capability | Limited by honing head stroke and stone wear | Strong on long tubes, single continuous pass |
| Form correction | Corrects roundness, taper, straightness well | Improves finish and size, less correction of gross form error |
| Stock removal capacity | High, handles out-of-round starting tube | Lower, needs a more consistent starting bore |
Where the burnished surface helps
The rollers do not just smooth the wall, they plastically deform it. That introduces compressive residual stress at the surface and raises local hardness. Compressive surface stress is generally helpful where the bore is exposed to pressure cycling, because fatigue cracks need tensile stress to propagate.
The trade is oil retention. A burnished surface holds less oil than a cross-hatched honed surface. For cylinders running conventional seals with good lubrication, this rarely shows up. For cylinders that run dry at start-up, or that use seal materials with poor oil film tolerance, the honed cross-hatch is the safer specification.
Where honing still wins
Honing corrects form that SRB cannot. If the starting tube has significant ovality, taper or waviness, skiving follows that error while honing averages it out. A honing head in continuous contact with the whole circumference removes material preferentially at the tight spots, which is why honed bore geometry regularly comes out better than the machine that produced the raw hole.
Honing also offers control that SRB cannot match: cross-hatch angle, plateau finish, and the Rpk / Rvk relationship that governs run-in and long-term seal lubrication. Where those parameters are specified, honing is the answer.
Cost, honestly stated
SRB is a single continuous pass and tends to be faster per metre, particularly on long tubes where honing would need multiple strokes and stone dressing. On a cost-per-metre basis SRB often wins on long, large-bore, high-volume tube where the starting bore is already consistent.
That advantage narrows or reverses when the incoming tube is inconsistent, when tolerance is tight enough to need in-process gauging, or when volume is too low to amortise tooling. A single-piece custom bore is usually more economical on a honing line, because SRB tooling is diameter-specific and the setup cost has to be recovered.
Choosing on four questions
- Is the starting tube consistent? If yes, both work. If no, honing corrects and skiving follows.
- Does your seal package need oil retention or a hard smooth wall? Oil retention points to honing with a specified cross-hatch. Wear resistance under clean lubrication points to burnishing.
- How long is the tube and how many do you need? Long and many favours SRB. Short, varied and few favours honing.
- Is the surface specification only Ra, or also Rpk, Rvk and angle? Only Ra leaves the choice open. The fuller specification generally requires honing.
What is on our floor
We run [ORISE: confirm which of the two processes are in-house, with diameter and length ranges for each]. Where a required size falls outside a confirmed in-house range we say so rather than quoting a capability we have not demonstrated. Process pages: deep hole boring and honing, and cylinder tubes and barrels.
If you are specifying a bore for a new design, send the drawing and the annual volume to the RFQ page and ask for both routes quoted. The comparison is more informative than any general rule.