A drilling test rig for model milling was designed and optimized. Extensive tests were conducted with the aid of the model scale drilling rest rig. These tests showed that the common cutting theories of metal machining can also be used for optimizing the casing milling process in the field. The first tests were performed with conventional inserts. Care was taken to the fact that the geometry of the inserts attached on the laboratory milling tool were almost identical to those used in the field. In addition to the common design, even inserts with a modified rake angle and made from special tungsten carbide were tested. All tests were documented by using a high speed camera to evaluate the cutting process and chip development in detail. Tens of casing milling tests have been successfully conducted with the casing milling test rig at the institute using conventional and FHP-inserts. Test results confirm that longer chips are formed and produced at high rotational speeds. According to the available test results, shorter chips were observed at lower rotational speeds compared to higher rotational speeds. The trend of the insert wear increases with increasing the forward velocity for all rotational speeds. The FHP-insert with the cobalt content of 10 % showed to be war resistant compared to the conventional insert. Furthermore, innovative ideas for improving the milling process have been described and feasibility studies have been started.