Honed bore
/glossary/honed-boreInternal surface finished by abrasive honing to precise diameter and surface roughness.
In detail
Honed bore refers to the internal surface finishing of a tube using abrasive honing stones that produce a controlled cross-hatch pattern and precise diameter tolerance. Honing achieves bore tolerances of H8 (±0.027 mm at 50 mm) or H9, and surface roughness Ra 0.2-0.4 μm. Honed-bore tubes (often designated BK+S H8) are mandatory for hydraulic cylinders to ensure proper piston seal contact and prevent leakage. The process follows cold drawing for seamless hydraulic tubes per DIN 2391.
Where you'll meet this in procurement
You will meet Honed bore in manufacturing notes, surface-finish call-outs, and precision-tube RFQs. Confirm that Honed bore is required for the duty (tolerance, bore finish, or coating), and that the quote states the same process the inspector will verify on receipt.