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Title:Development of a hybrid process for manufacturing surgical-grade knife blade cutting edges from bulk metallic glass
Author(s):Krejcie, Alexander J.
Advisor(s):Kapoor, Shiv G.; DeVor, Richard E.
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Surgical Blade
Bulk Metallic Glass
Deformation Study
Blade Cutting Performance
Abstract:The demand for precision surgical knives is enormous. Currently, diamond knives have been the preferred choice among surgeons for use in precision surgeries, owing to the extreme hardness of diamond and the sharpness that can be achieved in single crystal diamond blades, but material and processing costs are high. Bulk metallic glass (BMG) has the potential to be an economically-viable material of similar performance for use in precision surgical knives. To this end, a novel hybrid manufacturing process integrating thermally-assisted micromolding and micro-drawing has been developed for producing BMG surgical-grade knife blade cutting edges with edge radii <25 nm. A hybrid process testbed was designed and used to successfully run tests over a range of the key process variables. Three distinct deformation types were observed and were dependent on the balance between necking and elongation during drawing. The amount of necking and elongation was determined by the free volume behavior of bulk metallic glass and the formation of nano-crystals. Both these phenomena were found to be influenced by the atomic mobility of the material, which is based on both the material temperature and induced strain. A second generation hybrid manufacturing process and testbed were developed to improve blade straightness, edge radius and repeatability. The enhancements made included symmetric dies, an alignment flexure and force-limited drawing. Experimental results from the second generation process exhibited straight edges with less than 10 μm of deviation across the blades 2mm width and edge radii as low as 14 nm. Repeatability was also improved with all tests generating a viable cutting blade with comparable necking behavior, straight edges. Two processes were proposed to enable the manufacturing of multi-facet blades; a process based on forces generated by a magnetic field and a process based on multi-stage molding. Initial testing of the magnetic drawing process with a modified testbed revealed low forces relative to friction and inconsistent heating and it was concluded that magnetic drawing would not be able to produce meaningful results without major changes to the existing testbed. A review of previous research on tissue modeling and tissue cutting in terms of analyzing blade cutting performance was conducted. Based on this review, a testbed design and testing method was proposed with which to perform extensive analysis of blade cutting performance. The proposed method consisted of basic blade characterization, incision testing and wear resistance testing.
Issue Date:2011-08-25
Rights Information:Copyright 2011 Alexander J. Krejcie
Date Available in IDEALS:2011-08-25
Date Deposited:2011-08

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