Understanding Material Removal Mechanism and Effects of Machining Parameters during EDM of Zirconia-Toughened Alumina Ceramic

Abstract

Non-conductive structural ceramics are receiving ever-increasing attention due to their outstanding physical and mechanical properties and their critical applications in aerospace and biomedical industries. However, conventional mechanical machining seems infeasible for the machining of these superior ceramics due to their extreme brittleness and higher hardness. Electro discharge machining (EDM), well known for its machining of electrically conductive materials irrespective of materials hardness, has emerged as a potential machining technique due to its noncontact nature when complemented with an assistive electrode technique. This paper investigates the material removal mechanism and effects of machining parameters on machining speed and dimensional and profile accuracies of features machined on zirconia toughened alumina (ZTA) ceramics using assistive electrode EDM. Our experimental results demonstrate that both increasing peak current and pulse on time improves the MRR, however, it also aids in generating thicker layer on machined surface. In addition, pulse interval time is crucial for the machining of nonconductive ceramics, as larger value might cause the complete removal of intrinsic carbon layer which may lead to non/sparking condition. Higher peak current increases circularity whereas short pulse on and pulse off time aid in increasing circularity due to rough machining. In addition, taperness is found to be regulated by the peak current and pulse on time. Overall, thermal cracking and spalling appear to be a dominating material removal mechanism other than melting and evaporation for the EDM of ZTA.

Water-in-sunflower seed oil emulsion as a dielectric fluid for micro electrical discharge machining (µEDM)

“…It then cause the increase in circularity deviation, due to the occurrence of more sparks where the debris concentration are higher, which explain the dielectric breakdown easily occurs [45]. These results corroborate the findings of the previous work which found at higher peak currents, circularity increases, due to higher discharge energy which leads to bigger craters sizes [46]. Not only that, previous studies also found the effect of different dielectrics on the circularity at micro-EDM.…”

Phase Transformations and Subsurface Changes in Three Dental Zirconia Grades after Sandblasting with Various Al2O3 Particle Sizes

“…In contrast to 3Y-TZP, the cracks were interconnected and those intergranular or transgranular cracks could facilitate the zirconia material removal during the sandblasting [ 31 ] as the particle size increased in 4Y or 5Y subgroups. The propagation of microcracks was oriented parallel to the surface and those lateral cracks were located up to 4.5 µm distance under the surface in 4Y or 5Y subgroups.…”

Multi‐Objective Optimization During Magnetic Field Assisted ECDM of Alumina‐Zirconium Dioxide Ceramic Composite using Battle Royale Optimization

“…However, researchers machined Al 2 O 3 -ZrO 2 using EDM by providing a very thin silver paint on its surface. [39] Some important applications of Al 2 O 3 -ZrO 2 ceramic composite are pump components, valve seats, bearing components, die inserts, etc. From Figure 1a, the XRD results show that Al 2 O 3 -ZrO 2 ceramic consists of alumina peaks and a small count of monoclinic zirconia with tetragonal zirconia phases.…”