Cutting Tool Coating And Its Performance Evaluation

Cutting tool coating technology has been widely applied and will play a vital role in advanced cutting technology, which will boost the cutting technology to a new trend of development– high speed, high efficiency and dry cutting. In addition, it is reported that more than 80% of cutting tools are coated in the area of advanced manufacturing. Therefore, studying of the cutting tool coating and its performance, developing high quality coating for various cutting condition, will contribute to the development of manufacturing.In this work, the specific properties of drilling, milling, tapping and turning were rounded studied for the sake of providing the preferred factors for which coating should consider. The oxidation resistance and friction coefficient, the resistance of impact toughness, the compactness and surface quality, and the intensity under high temperature were the priority factors for drilling, milling, tapping and turning processes respectively. According to these preferred factors, a series of coating were developed in the PLATIT PL1000 Nano-scale Vacuum Ion Coating system for different cutting applications which were listed as follows, AlTiN coating with 55% Al content for drilling of mid-carbon structural steel 40Cr, AlTiN / Si3N4 coating for milling of SKD11, multilayer of TiCN coating for tapping of QT500 and composite coating of TiN + Al2O3 + TiCN for turning of low carbon sulphur free cutting steel. Their high performances were revealed by systemic experimental study, particularly in analyzing the coating wear mechanism, cutting force, cutting temperature etc. In order to further study the cutting process considering the coating effects, a Finite Element model was developed for simulating the cutting process with coated tool. The composite coating of TiN + Al2O3 + TiCN was built for simulating the orthogonal cutting and several properties such cutting force, cutting temperature and effective stress on the cutting tool were studied. This part of study indicated that the cutting forces using coated tool were smaller than that of uncoated tool, and the simulated result of cutting force were consistent with the experimental result which showed the simulation was creditable. The highest cutting temperature was occured on the tool-chip interface near the cutting edge, which can arrive at about 450℃, but the temperature on the substrate was less than 100℃. Furthermore the relatively high temperature gradient was found in the coating. The highest effective stress was also appeared on the tool-chip interface near the cutting edge, and some high stress was discovered on the flank face. Though the simulation of cutting process, some tips in design coating are approached. On the one hand, the resistance of high temperature should be developed as possible, and the thermo insulating property should also be enhanced in order to avoid subside. On the other hand, the temperature gradient should be avoided which will raise inner stress between coatings.