No abstract

In this study, ductile mode chip formation in conventional cutting and ultrasonic vibration assisted cutting of tungsten carbide workpiece material has been investigated through experimental grooving tests using CBN tools on a CNC lathe. The experimental results show that as the depth of cut was increased there was a transition from ductile mode to brittle mode chip formation in grooving both with and without ultrasonic vibration assistance. However, the critical value of the depth of cut for ductile mode cutting with ultrasonic vibration assistance was much larger than that without ultrasonic vibration assistance. The ratio of the volume of removed material to the volume of the machined groove, f ab , was used to identify the ductile mode and brittle mode of chip formation in the grooving tests, in which f ab <1 indicates ductile mode chip formation and f ab >1 indicates brittle mode chip formation. For the same radius of tool cutting edge, the value of f ab at the ductile-brittle transition region either with or without ultrasonic vibration was less than 1. However, the f ab value with ultrasonic vibration assistance was close to 1. The experimental results demonstrate that ultrasonic vibration assisted cutting can be used to improve the ductile mode cutting performance of tungsten carbide work material.

Email: xdliu@,SIMTech.a-star.edu.sq p. Subsurface damage in single-crystal silicon induced by ultraprecision grinding was evaluated by means of transmission electron microscopy (TEM) [4, 51. Dislocations appeared in the subsurface zone beneath the amorphous layer and penetrated from 100 nm to 600 nm. However, the AbstractNanometric ductile cutting experiments of silicon wafers have been carried out using an ultraprecision lathe with a single crystal diamond tool in this study. The machined silicon wafer surfaces were examined by using a scanning examined by using an atomic force microscope (AFM). electron microscope (SEM), and their topographies were microcracks appeared Only the layer* The depth Of subsurface damage was p* SEM and AFM observations of the machined silicon wafer surfaces indicated that ductile mode cutting of silicon wafers could be achieved in a certain cutting condition and tool geometry. The wafer surfaces achieved in ductile mode cutting were much smoother than that achieved in brittle mode cutting. Viewing from the 3dimensional AFM and SEM photographs, in ductile cutting of silicon wafers feed marks were clearly displayed on the machined wafer surfaces. Cross-sectional observations using a SEM showed that in ductile cutting of silicon wafers the subsurface damage was largely reduced compared to that occurred in the fine grinding process, which would largely reduce the processing time and cost of the heave chemical-mechanical polishing process. Using the ductile cutting process to replace the fine grinding process in the current wafer fabrication will greatly increase the product quality and production rate, as well as largely reduce the production cost.