The aim of this project is to optimize the industrial production by reactive sputtering of a new coating W-C/N-M, where M can be any metal to achieve good properties of high temperature stability, wear and corrosion resistance.
Moreover, studies to adjust the tools geometry to the coating will be developed in order to achieve the best compromise between the surface properties and the cutting efficiency of precision cutting tools, evaluating the quality of the tools in real conditions.
The results achieved with the new developed W-C/N-Me coatings showed a continuous positive development considering the life-time of the cutting tools. The optimization of the target chemical composition and of the respective deposition conditions lead to very significant results, especially those related with the cemented carbide end mills. These were tested under real cutting conditions and showed different wear behaviour when using lubricant or only press air as coolant.
Coatings containing tungsten seem to have better high temperature wear resistance, also compared with some standard coatings. Under dry cutting conditions, the life-time could be increased up to 200 %, also when using the optimized SILVER-TiN and MULTILAYER coatings.
The best results were achieved with coatings deposited from a W(70)-Ti(30) target. Nitride coatings achieved the best results under dry cutting conditions and carbonitride coatings using emulsion as coolant and lubricant.
Once more could be confirmed that with increasing titanium content the quality of the coating increased similarily. On the other hand, the introduction of aluminium in the chemical composition of the target leads to a decrease of the coating quality.
The results achieved with coated HSS taps and formers were not very promising. The higher life-time of the tools was achieved with coatings deposited also from the W(70)-Ti(30) target. With nitride and carbonitride coatings some good results were achieved. The life-time was lower than that of the standard coatings and achieved not more than 75 % of the reference values.
For high speed steel taps the cutting forces can be reduced. Resuming the results of the tests, means the surface treatments, the clamp friction and tool wear can be reduced at the tap time life increased.
The development of new characterization methods for thin films was very useful and the results show very interesting relations to practical applications.
The development of new tool geometries lead to better results of the lifetime with standard coatings. For these purposes a new multilayer coatings was developed and deposited on cemented carbide end mills and drills, which can be commercialized.
The development of W-C/N-Me coatings lead to the optimization of the chemical composition of the target. The films deposited from the target W,Ti have very good adhesion and cohesion properties, high hardness and low friction coefficient values.
With the multilayer coating following advantages could be achieved:
- higher strength than the other coatings, which allows to use it for cutting tools working under interrupted cutting conditions
- higher temperature resistance than the standard Gold-TiN coating, i.e. higher cutting speed and feed rate are possible
- higher abrasive wear resistance than the standard TiAlN coating
- lower affinity to titanium, nickel or brass.
For technological development in coating applications in many sectors of the manufacturing industry it is necessary to adjust the production of new coatings which present good laboratory performance to the manufacturing process requirements. The cutting tool industry is endeavouring :
- to obtain a coating with properties more suitable to increase the efficiency of tools in service
- to adjust the tools design to the presence of the coating, which can change the function of the tool, designed to be used without coating, taking into account the coating deposition procedure.