The tungsten carbide is a material with high hardness, wear resistance, good chemical stability, and dimensional stability. Because of these characteristics, it is mainly used as a tool for cutting and molding such as molds, and casts required for manufacturing high value-added equipment such as automobile parts and medical equipment. However, it is difficult to process with the traditional machining methods because of the high toughness and hardness. To overcome these problems, a study of tungsten carbide machining processing using the ultrafast-laser was recently conducted. In this paper, the ultrafast lasers with the pulse duration of 190 fs, 5 and 10 ps, respectively, were used. When the experiments were conducted with pulse widths of 5 and 10 ps, respectively, micro-cracks were observed from the heat generated by the overlap of the laser pulses. Conversely, the machining processing using a laser with the pulse width of 190 fs showed a major advantage with no crack by minimizing the thermal effects.

CFRP (Carbon fiber reinforced plastic) has been widely used in different industries such as aerospace, automobile, sports and medical. Laser processing of CFRP has a great potential for industrial applications. In this paper researched the micro cutting and drilling of CFRP with 0.5 mm thickness using 1064 nm ytterbium nanosecond pulsed fiber laser. It also investigated machining characteristics of micro cutting and drilling according to laser power, frequency, scan speed and number of scan (or irradiation). Complete cutting and through-hole drilling were achieved with low frequency when the laser power was low and with low and middle frequency when the laser power increased. However, those were not achieved a frequency of 100 kHz. The cutting width increased when the power increased and decreased when the frequency and the scan speed increased. The hole size increased when the power and the number of irradiation increased and decreased when the frequency increased. In the case of micro hole array, the hole was blocked during the next hole machining when the hole spacing was narrow. The resin was melted by the heat thus blocking the pre-drilled hole. We devised the laser scan method, and the micro hole array with narrow hole spacing was fabricated successfully.

The fabrication of a micro column array using micro EDM (Electrical Discharge Machining) and eccentric tools was presented. With the eccentric tools, micro columns can be easily machined only by feeding the tool vertically, as is the case in mechanical drilling. Moreover, the tool electrode rotates very fast, which is helpful to flush dielectric fluid in the EDM. In this paper, four eccentric tools were machined, and a micro column was machined in a few minutes. Finally, a hundred micro columns with 200-300 μm in a diameter were machined on a metal plate. In this study, vibration-assisted EDM was introduced to improve the machining rate in the fabrication of eccentric tools. Also, the design parameters of eccentric tools were discussed.