Papers by Keyword: Mechanical Lapping

Abstract: The fast development of SAW requests higher quality surface of CVD diamond films. Nowadays the mechanical lapping method is one important way to polish CVD diamond films, but the processing cost is high due to the low machining quality and efficiency. This paper reports a new accelerant lapping technology base on mechanical lapping and exploratory studies the role of three kinds of metal of the iron, titanium and nickel in the process of lapping. Firstly, ANSYS/LS_DYNA was used to simulate the process of friction and cutting between the CVD diamond films and abrasive plate of different material to analyze the temperature distributing on the interface and weather it is helpful for lapping. Then, experiment researches were carried out using the abrasive plate with different accelerant materials ratio. The results indicate that titanium is the most potent accelerant for polishing, followed by iron and then nickel. Experimental study also found that the accelerant lapping can carried out effectively by using the abrasive plate made of different metallic materials as accelerant to the diamond film grinding.

Abstract: A brittle-ductile transition lapping mechanism is proposed for the mechanical lapping of ultra-precision diamond cutting tools, and then the critical depths of cut for brittle-ductile transition in different orientations and on different planes are deduced in theory. Combined the critical lapping depth with the contact accuracy between rotating scaife and lapped tool surface, the influences of processing factors on cutting edge radius are studied. Both the theoretical analyses and experimental results indicate that the vibration of lapping machine tool and surface quality of scaife have enormous influences on the sharpened cutting edge. And lapping compression force has an optimal value. Lapping rate should be considered when lapping velocity is selected. But the smaller the lapping velocity is, the littler the cutting edge radius sharpened. Finally, the optimal selections are performed for each influencing factor and a perfect diamond tool is lapped in ductile mode with a cutting edge radius of 30~40nm and a surface roughness Ra of 0.7nm.

Abstract: In order to avoid the stochastic damage of micro cleavage on cutting edge, a brittle-ductile transition lapping mechanism is proposed for the mechanical lapping of single crystal diamond cutting tools to direct the tools lapping. As expected, the critical depths of cut for brittle-ductile transition in different orientations and on different crystal planes are calculated. According to the theoretical results, the actual dynamic depth of cut is controlled within the critical depth of cut, which ensures that the tool lapping is carried out in ductile regime and the changes of cutting edge radius characterize with some specific time laws in lapping. Therefore, the time series and nonlinear least square methods are used to analyze the changing laws of cutting edge radius. As a result, a coupled model to build a bridge between the cutting edge radius changes and lapping time is developed. In terms of this developed model, a required cutting edge radius restricts a tool’s lapping time. Above all, the cutting edge radius is known in advance and has no needs measuring. So the production efficiency of diamond cutting tools is improved and its production cost is reduced accordingly.