Honing, Lapping and Super-finishing Machines

Honing, lapping and super-finishing equipment are used to improve surface finish or geometry to tight tolerances. Honing machines use small, bonded abrasive stones or superabrasive sticks mounted in a fixture that rotates and reciprocates when applied to the surface or bore being finished. Honing is used to correct the geometry and alignment of holes and to produce the surface required for the application.  Lapping machines generate very flat surfaces (geometry refinement) with extremely fine finishes by using loose abrasives in a carrier fluid where parts are processed between one or two large flat lap plates or platens. Compared to grinding and honing, lapping removes much less material. Finishes are measured in micron and nanometer ranges.  Superfinishing machines produce surfaces with a very fine or low roughness average (RA).  Superfinishing, microhoning or microfinishing machines produce surfaces with a very fine or low roughness average (Ra). A very fine grit stone or several fine bonded stones are rubbed against the surface of the workpiece.  Superfinishing is similar to honing, but finer or lower Ra finish is produced with limited stock removal. Superfinishing can not correct geometry to the same degree as honing.  Other devices for very fine finishing include equipment are designed for wafer planarization or chemical- mechanical polishing (CMP).  Wafer planarization or CMP processes are used to finish and maintain flatness of silicon wafer during chip fabrication.