Honing is abrasive machining with bonded geometrically undefined abrasive cutting edges whereby the multi-cutting point honing stones describe at least two components of motion with at least one of them not rotational (CIRP Dictionary of Production Engineering 2004). Honing serves to improve the shape, size, subsurface, and surface quality of the workpiece.
Theory and Application
The application focus of honing is the internal honing, for example, in automotive engineering such as finishing cylinder bores, crankshaft bores, fuel injection pump housings, etc. Another field of application is hydraulics and pneumatics.
Internal honing/bore honing
Short stroke honing/superfinishing
Longitudinal stroke honing
In Addition, honing can also be classified by the topography of the machined surface, e.g. plateau honing, spiral slide honing, or laser honing.
Kinematics and Forces
The design of honing machines depends on the workpiece to be machined. For the internal honing of large parts with diameters up to 1,100 mm and bore lengths up to 12,000 mm, “horizontal honing machines” with horizontally arranged spindles are used.
Internal honing of smaller workpieces with diameters from about 0.6–350 mm is often performed on “vertical honing machines.” These most prevalent machines have (often multiple) vertically arranged spindles and are used, for example, to machine cylinder crankcases.
For the honing of flat surfaces, so-called flat honing or fine grinding machines are used. The kinematic of flat honing can be described by a planetary gear, with the workpiece carriers as planet wheels rotating around a central driven sun wheel. The workpiece carriers are running on a flat honing wheel, which contains the abrasive grains and is driven in the opposite direction of rotation. To machine parallel faces of a workpiece, often two-wheel flat honing machines are used. Examples for parts being machined on a flat honing machine are bearing rings or cutting inserts.
External honing of cylindrically or eccentrically shaped parts like camshafts, pins, and printing rolls is performed on superfinishing machines to improve the surface quality after a grinding process. While the workpiece rotates, the honing tool is permanently pressed on the lateral surface and oscillates in axial direction. The honing tool can be either a stone or an abrasive tape (Rao 2000).
Feed Systems for Cylindrical Honing
In cylindrical honing, basically two feed devices are used – the hydraulic and the mechanical feed device (Flores 1992; Grote and Antonsson 2009). At the hydraulic feed device, a constantly pressurized piston provides a constant advancing force Fz. Thus, the hydraulic feed device can also be called “force dependent.”
At the mechanical feeding, a feed moment Mz is converted to a defined displacement by a threaded gear or a step motor, whereby the honing pressure of the honing stones against the workpiece builds up. So, the mechanical feed device can also be called “path dependent.”
Single Stone Honing Tools
At the expandable honing tools, the honing stone is fed constantly against the workpiece during the honing operation. When using single stone honing tools, support bars for the tool guidance in the processed bore are necessary. On the other hand, single stone honing tools allow to process very small bores up to about 5 mm diameter.
Multistone Honing Tools
Honing mandrels are electroplated abrasive tools with a single layer of diamond or CBN grains in a metallic bond. Thus, their diameter is pre-adjusted and not expanded during the honing process; honing mandrels are assigned to non-expandable honing tools even if they can be expanded in a small amount to compensate for wear. As another consequence of the pre-adjustment, only small stock removal capacities are possible. Higher stock allowances often require a multi-step process. Honing mandrels are used to process small bores with diameters from about 0.6–16 mm.
Gear honing enhances the flank and the pitch. In normal gear honing, only the honing ring is driven. Gear power honing introduces also a second synchronous and prestressed drive of the work wheel.
Honing rings are comparable to grinding wheels and therefore must be dressed at regular intervals using a diamond dressing wheel, which itself has helical or spur gear shape, but plated with diamonds.
Honing wheels consist of a disk-shaped steel body with an abrasive cutting layer, comparable to grinding wheels. According to this, the same cutting materials (ceramics, diamond, CBN) and bonds are used. For the improvement of the chip transport, the cutting layers are available with different patterns of grooves or can be assembled of multiple hexagonally shaped segments.
Form Honing of Cylinder Bores
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