ULTRASONIC ASSISTED TURNING OF HARDENED STEEL WITH MONOCRYSTALLINE DIAMOND
INTRODUCTION The demand for ultra-precise steel parts with optical surface qualities and complex shaped geometries is increasing and could be applied for plastic injection molding or precision glass molding processes. Nowadays optical molds for injection molding are coated with a nickel layer, in order to be able to machine the surface with diamond tools. Directly machined steel parts would decrease manufacturing time, making the coating process step unnecessary. Additionally, the life time of the mold is increased dramatically. Uncoated steel tools have a higher scratch resistance and no risk of delamination. Therefore the potential of directly machining steel with monocrystalline diamond is exceptionally high.
A novel free-form transducer for the ultra-precision diamond cutting of die steel
For diamond cutting of die steel, it has been shown that ultrasonic vibration-assisted cutting can reduce the chemical wear of diamond tool due to the discontinuous contact between the cutting tool and the workpiece. In this paper, a novel structure of transducer is designed by using free-form surface for ultrasonic vibration-assisted ultra-precision turning die steel. It has two interesting characteristics: The vibration direction of cutting tool tip can be changed by altering vibration frequencies; it can produce an elliptical vibration with only longitudinal vibration actuator. In addition, the structure of this transducer is simple and compact. Finally, several experiments were conducted to demonstrate the effectiveness of this system by diamond ultra-precision turning of STAVAX steel to a mirror surface.
Coronial Practice, Indigeneity and Suicide
All available data suggest that, like many other Indigenous peoples, Australian Aborigines are significantly more likely to kill themselves than are non-Aboriginal Australians. This statistical disparity is normally positioned an objective, ontological and undeniable social fact, a fact best explained as a function of endemic community disadvantage and disenfranchisement. This research explores the possibility that higher-than-normal Aboriginal suicide rates may also be a function of coronial decision-making practices. Based upon in-depth interviews with 32 coroners from across Australia, the following conclusions emerged from the data. First, coroners have differing perceptions of Indigenous capacity, and are less likely to have concerns about intent when the suicide is committed by an Indigenous person. Second, coroners have identified divergent scripts of Indigenous suicide, particularly its spontaneity and public location, and this supports rather than challenges, a finding of suicide. Third, the coronial perception of Indigenous life is a factor which influences a suicide determination for Indigenous deaths. Finally, the low level of Indigenous engagement with the coronial system, and the unlikelihood of a challenge to the finding of suicide by Indigenous families, means that a coronial determination of suicide is more likely.