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2-, 3- and 4-fold tools for internal machining of cylinders

The RDO and RIO tools equipped with the OMEGA peeling head machine cylinder liners. The liners can be pre-drilled, drilled, skived and roller burnished in a single pass as required. In addition, these tools effect correction of circularity defects in the liner and as a result twist is significantly reduced or even eliminated.


  • 2-fold tools for combined skiving and burnishing (RDO, RIO), 3-fold tools (RIOA) for combined drilling, skiving and burnishing, 4-fold tools (RIOA quattro) for combined pre-drilling, drilling, skiving and burnishing.
  • Tubes with radial circle irregularities up to 0.5 mm (.02”) are skived in one operation. The remaining circle irregularity is reduced to 0.01 mm (.004”). The wavyness existing in longitudinal direction is reduced simultaneously.
  • Diameter tolerances IT8 or IT9; surface roughness Ra = 0,05 - 0,4 (Rz = 0,5 - 2) micron attainable.
  • For applications without twist problems: Economy version with 2 skivers
  • For applications with twist problems; diameter range 60-400 mm: Version with 2 or 3 skivers
  • For applications with severe twist problems; diameter range 205-400 mm: Version with 6 skivers
  • The radial floating cutters center themselves in such a manner that both cutting edges remove almost identical thicknesses of chip.
  • Based on the tool control system (RETRAC- or international system) tool types RDO or RIO can be selected (for further information see tab "Tool control systems").

3D-View RIOA


Tool control systems

  RETRAC-System International System
Control cycle Treatment pressure-less, retreat with appr. 20 bar Treatment: 100 bar hydraulic pressure, retreat pressure-less
Area Mainly Europe Worldwide
Activation cylinder
RETRAC-cylinder intregrated in boring bar Hydraulic cylinder integrated in tool
Control connection Mechanical automatic connection in thread connection boring bar/tool Hydraulic automatic connection in thread connection boring bar/tool
Compatibl Tools
RDO (combined, skiving and burnishing) RIOA, RIOF, RIOK (2-, 3- or 4-fold combined (pre-drill, drill-out, skiving, burnishing))


  • Better circular and cylindrical form, avoidance or reduction of rippling.
  • Shorter process time by higher cutting speed and larger feed rates.
  • Treatment of tubes with bigger irregularities in one operation.
  • Larger cutting depth possible.
  • Longer life time of wear parts.
  • Drastically shortened machine down time.
  • Simple diameter adjustment.
  • Easy and fast exchange of the wear parts.
  • Segment cages simplify exchange of burnishing rolls with Ø ≥ 205 mm.

Basic construction

  • 2 (alternatively 3) skiving knives are supported by the RETRAC cone so that they can float together in radial direction. The cone is used for the central adjustment of the skiving diameter. For this, only an Allen key is inserted in the center bore at front side.
  • A clearly marked scale at the front side of the tool makes precise and reproducible adjustment easy. 
  • Larger axial travel through the RETRAC hydraulic system enables the skiving knives to retract into the idle position.
  • Skiving heads are connected with tool base by quick connect enabling fast and easy separation of skiving head and tool base without special tool.
  • The skiving knives come with two consecutively arranged cutting inserts (a) and (b).
  • The pre cutters are arranged with different selectable off-set of 0.1; 0.2; 0.4; 0.6 or 0.8 mm deeper than the final cutters. Exchangeable insert seats (c) position the cutters precisely.
  • After the treatment, skiving knives and burnishing rollers are hydraulically retracted in order to avoid damage of the surface during tool retraction.


  • RETRAC control system.
  • Skiving and roller burnishing of hydraulics cylinders and cylinder tubes with lengths until approximately 20 m of length.
  • Diameters 38 to 500 mm.
  • Tool bodies and roller heads are identically with older series RDS-R and RDZ. Conversion kits for upgrade to the OMEGA-System are available.


International control system


  • 3- and 4-fold tool for combined pre-drilling, drilling, skiving and burnishing of hot-rolled tubes.
  • The boring head is equipped with three cutter cassettes with one indexable insert each.
  • Three carbide guide pads serve for a clearance-free radial guide.
  • Maximum straightness deviation 0,5 mm/m.
  • The skiving head is equipped with three skiving knives.


  • Skiving head is rigid.
  • Recommended for tube lengths ≤ 4,5 m.
  • Version RIOF can be converted to RIOA by replacement of the front cover with a counter boring head.


  • The skiving head is floating.
  • Three guide pads Recommended for the treatment of tubes with a length > 4,5 m.
  • Eliminates wobbling, straightness failures and misalignments.
  • Avoids "black patches" (not skived black areas).