Abstract: A method of processing a workpiece with a first surface and a second surface facing away therefrom includes the following principal steps: (i) blocking the workpiece with the aid of a blocking material on a blocking member with the blocking material between blocking member and first surface, (ii) processing the workpiece by a geometrically defined cutting edge at the second surface for achieving the desired macrogeometry, (iii) processing the workpiece by a geometrically undefined cutting edge at the second surface for achieving the desired microgeometry and (iv) deblocking the workpiece from the blocking member. The principal step (ii) includes a plunge-cutting sub-step (ii.2) in which by a geometrically defined cutting edge an encircling plunge cut is produced which extends through the first surface as far as into the blocking material so that the workpiece with a predetermined edge profile remains on the blocking member radially within the plunge cut.

Abstract: A method of processing a workpiece with a first surface and a second surface facing away therefrom includes the following principal steps: (i) blocking the workpiece with the aid of a blocking material on a blocking member with the blocking material between blocking member and first surface, (ii) processing the workpiece by a geometrically defined cutting edge at the second surface for achieving the desired macrogeometry, (iii) processing the workpiece by a geometrically undefined cutting edge at the second surface for achieving the desired microgeometry and (iv) deblocking the workpiece from the blocking member. The principal step (ii) includes a plunge-cutting sub-step (ii.2) in which by a geometrically defined cutting edge an encircling plunge cut is produced which extends through the first surface as far as into the blocking material so that the workpiece with a predetermined edge profile remains on the blocking member radially within the plunge cut.

Abstract: An apparatus for the machining of optical workpieces of materials of non-brittle hardness, particularly of plastics material spectacles lenses, has a holder, which is operatively connected with an actuator for reciprocating movement, and a support, which is fixable to the holder and to which a cutting tip of monocrystalline diamond, which has an arcuate cutting edge, is fastened. In order to be able to use the cutting edge over its curve length to avoid of premature wear in the rotary machining, provision is made for a positioning device, by which the support is fixable in at least two different relative positions with respect to the holder to dispose substantially different circumferential sections of the cutting edge for the rotary machining.

Abstract: An apparatus for the machining of optical workpieces of materials of non-brittle hardness, particularly of plastics material spectacles lenses, has a holder, which is operatively connected with an actuator for reciprocating movement, and a support, which is fixable to the holder and to which a cutting tip of monocrystalline diamond, which has an arcuate cutting edge, is fastened. In order to be able to use the cutting edge over its curve length to avoid of premature wear in the rotary machining, provision is made for a positioning device, by which the support is fixable in at least two different relative positions with respect to the holder to dispose substantially different circumferential sections of the cutting edge for the rotary machining.