Characteristics of Micro EDM for Insulating Aluminum Nitride Ceramics
Aluminum Nitride (AlN) ceramic materials have high thermal conductivity and electrical insulation, prompting consideration of their use as a semiconducting material. Although AlN should be machined with a high accuracy of form and dimension to achieve products and components with requisite precision, mechanical and other machining methods such as the laser method cannot be used because of the brittleness and high thermal conductivity of AIN. Recently, we have succeeded in machining many insulating ceramics by sinking (SEDM) and Wire-Electrical Discharge Machining (WEDM) with the assisting electrode method. We have already machined many insulating ceramic materials such as Si3N4, ZrO2 and Al2O3. However, inferior machining characteristics were obtained with AlN than with other materials. In this study, the effects of several electrical discharge conditions were examined to obtain better machining properties, such as high material removal rate and a low electrode wear ratio. It was found that machining time decreased with an increase in capacitance, while the electrode wear ratio increased. The electrode wear ratio of the W electrode was low, suggesting that it is suited for accurate machining of AlN. Additionally, the electrically conductive layer was analyzed using Energy Dispersive X-ray Spectrometry (EDS) and X-ray Diffraction (XRD). As a result, the architectural component of the EDMed AlN surface is considered mostly Al that is resolution of the workpiece. Therefore, in the EDM of AlN using the assisting electrode method, machinability using deionized water may be superior to dielectric oil. To investigate the effect of the dielectric working fluid, AlN was machined using deionized water and dielectric oil. In the case of machining with deionized water, the removal rate was faster and electrode wear ratio was lower, compared to dielectric oil.
Zone-Ching Lin, You-Min Huang, Chao-Chang Arthur Chen and Liang-Kuang Chen
K. Kaneko and Y. Fukuzawa, "Characteristics of Micro EDM for Insulating Aluminum Nitride Ceramics", Advanced Materials Research, Vol. 579, pp. 86-91, 2012