The objective of this project is to test the following two hypotheses: 1) the combined action of laser and waterjet will result in development of tensile stresses perpendicular to cutting path and propagation of cracks along cutting path during the two-dimensional cutting and 2) if the material removal mechanism were changed from thermal melt and evaporation (laser cutting) or material erosion (electrical discharge machining) to material separation through crack propagation, then smaller kerf; parallel walls; higher cutting speed and substantial energy savings can be attained in the machining of two-dimensional profiles of polycrystalline diamonds and polycrystalline cubic boron nitride over conventional machining processes. The project's approach is to test the hypotheses relies on fundamental fracture mechanics modeling and experiments to investigate controlled fracture of superhard materials due to thermal and chemical effects of laser heating and waterjet quenching.
Successful completion of the research activities will lead to a novel machining method for brittle materials along with a detailed understanding of the fundamental underpinnings behind this new process. This novel hybrid manufacturing process will have potential to offer high performance tools and dies for metal cutting and wire drawing industries respectively. Automotive, woodworking and other industries that use synthetic diamond tools would greatly benefit from this research. Education and outreach outcome will include training of graduate students in advanced manufacturing research, assimilation of the research outcomes into new course modules, the involvement of undergraduates from underrepresented groups in the research team and the dissemination of the research results through journal publications, conferences and industry visits and workshops.
The goal of our research is to improve the speed, precision, surface finish and energy savings in two dimensional profile cutting of superhard tool polycrystalline cubic boron nitride through a novel laser/waterjet hybrid manufacturing process facilitating an increase in industrial productivity and reduction in material waste. The interllectual merit of the work conducted was that we tested and verified the following two hypothesis: a) Combined action of laster and waterjet results in transformation of superhard materials and development of tensile stresses perpendicular to cutting path and propagation of cutting cracks along cutting path during two dimensional cutting of cubic boron nitride; and b) Changing the material removal mechanism from thermal melt and evaporation (laser cutting) or erosion (waterjet cutting) to material separation through crack propagation led to improvement in cutting speeds (over ten times faster), smaller heat affected zones and substantial energy savings in cutting of cubic boron nitride tools. Research results show that the hybrid machining process enable splitting of pure cubic boron nitride as well as CBN coated tungsten carbide tools at high cutting speeds but suffers from roughness of curt surfaces. These results demonstrate that the manufacturing process can be further developed to be an excellent alternative to currently used methods for cutting and machining superhard materials. Research formed part of three masters thesis and two PhD dissertations and studnets were trained in mechanics, materials science and manufacturing research. Research results were disseminated through five journal publications and one conference proceeding.
