CNC 28 M, the two sided machine The CNC 28 M double sided, internal, external and surface grinding machine guarantees very short machining times and maintenance of high shape and position tolerances because up to 4 grinding wheels machine the workpiece simultaneously. This is made possible by the center drive with high precision hydrodynamic or hydrostatic workpiece spindle. The machine can process a wide spectrum of workpieces. This includes, among others, two sided machining of housings, drive shafts, hydraulic parts and many others.