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Navas V.G.,IK4 TEKNIKER CIC marGUNE | Sanda A.,IK4 TEKNIKER CIC marGUNE | Sanz C.,IK4 TEKNIKER CIC marGUNE | Fernandez D.,IK4 TEKNIKER CIC marGUNE | And 3 more authors.
Journal of the European Ceramic Society

Al2O3 and ZrO2 based ceramics are extremely difficult to manufacture, being rotary ultrasonic machining (RUM) an interesting machining process for these materials. In this work the effect of RUM on the final surface integrity of ZrO2-TiN and Al2O3-TiC-SiC ceramics has been studied. During RUM of these ceramics two material removal modes co-exist: brittle and ductile fracture. In Al2O3-TiC-SiC prevails the ductile fracture mode whereas in ZrO2-TiN the brittle fracture mode predominates. Lower surface roughness is obtained if diamond tools with smaller grain size are used, the axial depth of cut is reduced and/or the feed rate is increased. RUM generates compressive surface residual stresses in both ceramics. Machining parameters have no effect on final residual stresses in ZrO2-TiN, but in Al2O3-TiC-SiC more compressive stresses are generated when feed is reduced and/or axial depth of cut is increased. RUM of ZrO2-TiN does not induce any detrimental tetragonal→monoclinic phase transformation of ZrO2. © 2015 Elsevier Ltd. Source

Garcia Navas V.,IK4 TEKNIKER CIC marGUNE | Fernandez D.,IK4 TEKNIKER CIC marGUNE | Sanda A.,IK4 TEKNIKER CIC marGUNE | Sanz C.,IK4 TEKNIKER CIC marGUNE | And 2 more authors.
Procedia CIRP

Nowadays the use of new high strength alloys is growing, but these alloys are difficult to machine due to the high temperatures generated during cutting. A solution is the use of cutting fluids, but those have adverse environmental effects, health risks and high costs of purchase, storage and maintenance. An emerging alternative is the use of cryogenic fluids such as liquid nitrogen (LN2). Nevertheless, in order to accept a new machining process industrially, it must be assured that final structural integrity of the machined part is at least as good as that generated by conventional machining processes. Therefore, in this work it has been compared the surface integrity (roughness, hardness, residual stresses and microstructure) generated in AISI 4150 (50CrMo4) steel by dry turning, turning with lubricant (oil based emulsion) and cryogenic turning with LN2. The results prove that cryogenic machining is the best solution since it reduces machining problems of heating, leading to tool life improvement and better surface integrity of turned components. © 2014 The Authors. Published by Elsevier B.V. Source

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