DIAMOND MICRO CHISELING OF MOLDING INSERTS FOR OPTICAL MICRO STRUCTURES

摘要

The process strategies described above were tested by machining an electroless nickel coating molding insert with several arrays of optical micro structures. Fig. 6 shows an example how V-grooves and four-sided small cavities can be combined to form a riblet structure. The second example (fig. 7) is an array of cubic retro reflectors with hexagonal aperture [2]. The surfaces are of optical quality with a roughness Ra<10nm, flatness PV < 50 nm and are free of artifacts. The effect of tool radius compensation is clearly visible as the edges and corners are sharp and only an insignificant small area in concave corners remains undefined.rnBy reducing the contact length of the minor cutting edge the better understanding of thernmechanism of cutting force generation was used when machining these samples to decrease the amount of cutting force per cross-sectional area of uncut chip. This allows lager cross-sections, shorter machining time and increased tool life. Better surface quality is gained as no effect of kinematic roughness occurs when finish machining micro mirror facets with a single cut cutting width being b = t~*. Also the concept of pre and finish machining by utilizing two dedicated tools reduces machining time and quality, as the main load is taken by the robust pre-machining tool. Nevertheless, the machining time is quite high and future work will deal with further reduction. The maximum cutting speeds are not limited by the DMC process itself, but by the dynamics of the machine tool and stiffness of the DMC diamond tool. Here lies a large potential for further optimization.