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Fritz Klocke,Tolga Cayli,Dieter Lung,Benjamin Döbbeler,Hubertus Sangermann 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
In the field of machining difficult-to-cut materials like titanium or nickel-based alloys, the use of high-pressure cooling lubricantsupply (HPCLS) offers huge potential to significantly increase productivity and process stability. Due to enhanced cooling andlubrication of the cutting zone, tool wear can be decreased which allows higher applicable cutting speeds. Furthermore, processstability can be increased through effective chip breaking and evacuation. Increasing energy prices and legislative frameworkconditions, require energy efficient machine tools and processes. Since additional energy is required to run the high-pressure pump,it has to be determined if the overall process is still energy-efficient due to the increase in productivity resulting in shorter cycle times. In this paper the overall aim is to evaluate the conventional-flood-cooling and HPCLS in terms of economics and energy efficiency. Therefore a case study has been performed in which the energy consumption and production times for machining a rotationallysymmetric jet engine part made of Inconel 718 were compared for both conventional and HPCLS. Furthermore, an ecologicalevaluation has been conducted to determine the advantageousness of the HPCLS. Due to the rising necessity of suppliers to providea product carbon footprint, a methodology for assessing the footprint has been applied.
Biomechanical Assessment of Stabilization of Simulated Type II Odontoid Fracture with Case Study
Roy T. Daniel,Mir M. Hussain,Noelle Klocke,Soumya S. Yandamuri,Lukas Bobinski,John M. Duff,Brandon S. Bucklen 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.1
Study Design: Researchers created a proper type II dens fracture (DF) and quantified a novel current posterior fixation technique with spacers at C1–C2. A clinical case study supplements this biomechanical analysis. Purpose: Researchers explored their hypothesis that spacers combined with posterior instrumentation (PI) reduce range of motion significantly, possibly leading to better fusion outcomes. Overview of Literature: Literature shows that the atlantoaxial joint is unique in allowing segmental rotary motion, enabling head turning. With no intervertebral discs at these joints, multiple ligaments bind the axis to the skull base and to the atlas; an intact odontoid (dens) enhances stability. The most common traumatic injury at these strong ligaments is a type II odontoid fracture. Methods: Each of seven specimens (C0–C3) was tested on a custom-built six-degrees-of-freedom spine simulator with constructs of intact state, type II DF, C1–C2 PI, PI with joint capsulotomy (PIJC), PI with spacers (PIS) at C1–C2, and spacers alone (SA). A bending moment of 2.0 Nm (1.5°/sec) was applied in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). One-way analysis of variance with repeated measures was performed. Results: DF increased motion to 320%, 429%, and 120% versus intact (FE, LB, and AR, respectively). PI significantly reduced motion to 41%, 21%, and 8%. PIJC showed negligible changes from PI. PIS reduced motion to 16%, 14%, and 3%. SA decreased motion to 64%, 24%, and 54%. Reduced motion facilitated solid fusion in an 89-year-old female patient within 1 year. Conclusions: Type II odontoid fractures can lead to acute or chronic instability. Current fixation techniques use C1–C2 PI or an anterior dens screw. Addition of spacers alongside PI led to increased biomechanical rigidity over intact motion and may offer an alternative to established surgical fixation techniques.
Atomic diffusion induced degradation in bimetallic layer coated cemented tungsten carbide
Peng, Zirong,Rohwerder, Michael,Choi, Pyuck-Pa,Gault, Baptiste,Meiners, Thorsten,Friedrichs, Marcel,Kreilkamp, Holger,Klocke, Fritz,Raabe, Dierk Elsevier 2017 Corrosion science Vol.120 No.-
<P>We investigated the temporal degradation of glass moulding dies, made of cemented tungsten carbide coated with PtIr on an adhesive Cr or Ni interlayer, by electron microscopy and atom probe tomography. During the exposure treatments at 630 degrees C under an oxygen partial pressure of 1.12 x 10(-23) bar, Cr (Ni) was found to diffuse outwards via grain boundaries in the PtIr, altering the surface morphology. Upon dissolution of the interlayer, the WC substrate also started degrading. Extensive interdiffusion processes involving PtIr, Cr (Ni) and WC took place, leading to the formation of intermetallic phases and voids, deteriorating the adhesion of the coating. (C) 2017 The Authors. Published by Elsevier Ltd.</P>