High performance - down to the smallest detail

Honing

The variety of honing processes available enable us to precision-machine your workpieces quickly, economically and with the maximum possible benefits:

  • Increased part service life, particularly with the following parts
    • Connecting rods, piston bearing surfaces, main bearing bores, brake and clutch cylinders, gear wheels, camshaft bearings and rockers
    • Control housings, valve blocks and pressure cylinders
    • Chassis tubing, control housings, and gun, rifle and pistol barrels
  • Honing determines and improves important engine parameters such as friction, wear and reliability
  • Increased geometric accuracy
  • Enables task-specific surfaces to be created
  • Honing as reworking reduces numbers of reject parts
  • Supply of replacement parts with economic end of lifetime
  • Our solutions are quick to implement, enabling us to integrate them into your production system rapidly and reliably

Standard materials for honing processes

  • All ferrous and non-ferrous metals
    • Materials with a nickel or cobalt base
    • With or without heat treatments
    • With or without surface treatments
  • Sintered materials
  • Ceramic materials
  • Glass

The overlapping cutting movement in honing is significantly different to grinding, with the tool rotating while simultaneously moving up and down, as also is the constant and widespread contact between the tool and the workpiece in honing. As with lapping, in honing the tool must be exactly matched to the workpiece geometry. By contrast, the abrasives used in honing tools are mechanically bonded to the honing bar or stone. Most honing stones are manufactured in silicon carbide or corundum; for maximum service life, diamond can be used. A self-sharpening effect can be obtained for hard materials through soft bonds and vice versa. The cutting motion is achieved through one oscillating movement and another counter-movement, such that their directions of movement cross at an angle of between 40 and 60 degrees on the forward and return movements.

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Comparison of long-stroke and short-stroke honing

The two basic forms.

Long-stroke honing – this method is normally used for honing internal surfaces, such as those of bores or tubes. An awl-like honing tool is used for this purpose. It consists of prismatically-shaped honing stones set into a metal core, so that the external contour of the tool corresponds to the geometry of the workpiece. To compensate for wear to the tool, the honing stones are either spring-loaded or mechanically, hydraulically or pneumatically adjustable. Honing tools with sprung or pneumatically mounted honing stones can only be used for improving surface quality. Mechanically or hydraulically adjustable stones, on the other hand, can also be used to reduce geometric errors such as roundness or cylindrical form.

As a manufacturing technique honing can be primarily divided into two basic forms. In long-stroke honing the oscillating movement of the honing tool typically covers the whole of the length of the workpiece. By contrast, in short-stroke honing the tool oscillates only within an amplitude of millimetres. Each of these methods has its own specific fields of application.

Short-stroke honing – this is typically used for honing external surfaces. For small series and one-off production, there are tools that can be attached to lathes or grinding machines and that generate the oscillating motion of the honing stone necessary for honing with a pneumatic drive, for example. Combined with the rotary movement and feed control of the main machine (lathe or grinder), this arrangement can also be used for machining shafts and other turned parts.

Example applications of honing:
• Cylinder bore surfaces of automotive combustion engines
• Valve seats of high-pressure injection systems in common-rail diesel engines

Precision levels achievable with honing:
• Diameter tolerance +/- 0.0005 mm ( = +/- 0.5 µm)
• Surface roughness up to Rz 0.04