Impact of Hard Machining on Zirconia Based Ceramics for Dental Applications

Since the late 90s the use of zirconia based all-ceramic restorations increases. Many manufacturing steps are necessary, like pre-sintering, soft machining (pre-sintered condition), sintering and hard machining (fully sintered) in combination with a final staining or veneering step. All these techniques, especially hard machining, are associated with the production of flaws in different scales, in conjunction with thermal and residual stresses and phase transformations. These are inter alia capable to induce failure. This work investigates the impact of hard machining on the material properties and attempts to establish a correlation to failure. © 2016 Published by Elsevier B.V

Material Removal Mechanisms in Grinding of Mixed Oxide Ceramics

The technological basis for a cost-effective and reliable grinding process of mixed oxide ceramics requires a fundamental understanding of the prevailing grinding mechanisms to maintain surface quality and strength requirements. However, these material removal mechanisms are not yet fully understood. This paper presents an innovative quick stop device for the interruption of cut during grinding. This appropriate method allows a detailed analysis of the interactions of grains along the contact zone. The results reveal correlations between the prevailing grinding mechanisms, the tetragonal to monoclinic phase transformation of the zirconia based ceramics as well as the resulting bending strength. © 2016 The Authors. Published by Elsevier B.V

A comparative analysis of ceramic and cemented carbide end mills

Milling of ferrous metals is usually performed by applying cemented carbide tools due to their high hardness, temperature and wear resistance. Recently, ceramic tool materials have been on the rise and enhanced the efficiency in machining. As ceramics are brittle-hard materials, tool manufacturing requires a sound knowledge in order to meet the tool requirements such as sharp cutting edges and wear resistance. In this study, milling tools made of the high performance ceramic SiAlON were compared to tools made from cemented carbide. For both tool materials, the influence of a prepared cutting edge was investigated. Both the tool manufacturing process and the cutting edge preparation processes are presented, followed by the application of those tools within milling experiments. In order to evaluate the efficiency of both tool types, the cutting forces and the cumulative process energy demand were analyzed. Additionally, surface roughness of the machined workpieces and tool wear were examined. It was found that the ceramic tools, although process forces were higher than for cemented carbide tools, exhibited by far lower energy consumption, less tool wear and finally generated lower surface roughness. © 2020, The Author(s)

Best Practice in Nuclear Medicine 2

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