Abstract
The setting of cutting variables for precision milling of ceramics is important to both the machined surface quality and material removal rate (MRR). This work specifically aims at the performance of corner radius PCD (polycrystalline diamond) end mill in precision milling of zirconia ceramics with relatively big cutting parameters. The characteristics of the cutting zone in precision milling ceramics with corner radius end mill are analyzed. The relationships between the maximum uncut chip thickness (hmax) and the milling parameters including feed per tooth (fz), axial depth of cut (ap) and tool corner radius (rε) are discussed. Precision milling experiments with exploratory milling parameters that cause uncut chip thickness larger than the critical value were carried out. The material removal mechanism was also analyzed. According to the results, it is advisable to increase fz appropriately during precision milling ZrO2 ceramics with corner radius end mill. There is still a chance to obtain ductile processed surface, as long as the brittle failure area is controlled within a certain range. The appropriate increasing of ap, not only can prevent the brittle damage from affecting the machined surface, but also could increase the MRR. The milling force increases with increasing MRR, but the surface roughness can still be stabilized within a certain range.
Highlights
The results demonstrated the feasible manufacturing of complex shapes and micro features
The additive manufacturing (AM) processes for ceramics use ceramics in powder form, and AM techniques can directly be applied to a ceramic slurry and provide in-situ sintering
Itiscan be seen from the Equation that the maximum uncut chip thickness max in the cutting zone is affected by the feed per tooth fz, axial depth of cut ap and the corner radius of the tool nose rε
Summary
Thanks to the favourable combination of outstanding mechanical, thermal and chemical properties, advanced engineering ceramics, such as oxides, carbides, nitrides, and borides, have received growing attention in modern industries. Zirconia ceramics (ZrO2 ) have the highest fracture toughness (KIC between 4 and 12 MPa/m1/2 ) and flexural strength, combined with ionic conductivity, excellent thermal insulating properties and biocompatibility properties. The approach suitability is mostly limited to some electrically conductive ceramics, such as carbides and composites It is the reported the machined surface presents thermal-induced micro-cracks, which may cause adverse effects on the operational performance of some precision components. The AM processes for ceramics use ceramics in powder form, and AM techniques can directly be applied to a ceramic slurry and provide in-situ sintering By this way, three-dimensional complex parts can be obtained. Depending on the final required tolerance and surface quality of the part, especially for the precision part, final machining still might be needed [3]
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