In internal honing, the workpiece remains stationary. A honing head, equipped with grinding stones around its circumference and floatingly connected to the machine tool spindle, serves as the tool. Under pressure, the relative movement of the honing head against the inner surface of the workpiece removes a very thin layer of metal from the machined surface. During honing, the grinding stones on the honing head undergo three movements: rotary motion, axial reciprocating motion, and radial feed motion perpendicular to the machined surface. The first two movements are the primary movements of the honing stones, and their combined effect creates a crisscrossing, non-repeating cutting pattern on the machined surface. (Tongchao Precision Grinding)

Similar to machining, the ratio of the maximum speed of the axial reciprocating motion of the grinding wheel to the speed of the rotary motion forms the main parameter affecting surface roughness and productivity—the maximum cutting angle. The radial feed motion is the radial feed made by the grinding wheel under pressure as the metal layer on the machined surface is removed. This radial feed amount varies with the pressure of the grinding wheel on the inner hole surface.

During internal honing, a very low surface roughness can be achieved due to the large number of abrasive grains simultaneously participating in the cutting, the very low pressure on the honing strip, and the minimal repetition of the abrasive grain cutting trajectories. The properties, hardness, and binder of the abrasive used in internal honing directly affect the surface roughness and productivity. White alumina and green silicon carbide are commonly used abrasives for honing strips. Adding 20-30% graphite powder to the abrasive increases the frictional polishing effect of the abrasive grains on the machined surface, reducing surface roughness. Clay, resin, or rubber are commonly used binders for honing strips. Resin or rubber binders have good elasticity, enhancing the polishing effect of the honing strip and achieving a lower surface roughness; they are generally used for semi-finish and finish honing. The hardness of the honing strip also significantly affects the honing process. Softer honing strips have better self-excitation, stronger cutting action, and higher productivity, but are more prone to scratches on the machined surface. Hard grinding wheels have poor cutting performance, but produce a low surface roughness after machining.