Development of a hybrid thermoplastic forming process for the manufacture of multi-facet and curvilinear surgical blades from bulk metallic glass

Bulk metallic glasses (BMGs) are multi-component alloys that have formed an amorphous atomic structure. This class of materials exhibit a unique combination of high strength/hardness and high elastic limit that is ideal for the formation and retention of a sharp edge. At high temperatures above the glass transition temperature, BMG begins to exhibit softening behavior and transitions to a supercooled liquid regime. This supercooled state allows the use of economically-viable thermoplastic forming techniques that are typically not available to metals and other hard materials. BMG has therefore been identified as an alternative material for precision surgical blades with the potential of tremendous cost savings. A hybrid thermoplastic forming processing involving sequential micro-molding and micro-drawing operations is developed to manufacture the multi-facet/curvilinear geometries found on most surgical blades. This is accomplished through an oblique drawing technique, i.e. drawing with a non-zero inclination angle. By applying time-varying force profiles during the drawing operation, a wide range of complex blade geometries are possible. A manufacturing testbed has been designed, assembled, and automated based on the oblique drawing concept. To facilitate a smooth drawing operation, a supervisory control algorithm has been specifically developed to switch between force-feedback and velocity-feedback controllers. Experiments have exhibited positive results across several multi-facet and curvilinear blade geometries. Manufacturing process capabilities are quantitatively evaluated and experimental results have measured cutting edge radii to be consistently less than 15 nm, rake face surface finish Ra to be on the order of 20 nm, and edge straightness deviations to be less than 5 µm RMS. Measurements are made at several locations along blade samples as well as across various blade geometries. A high degree of repeatability of edge radius, surface finish, and straightness are found both within a single sample as well as among different blades.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Zhu, James

Contributors dc:contributor

• Kapoor, Shiv G.

• Multi-Facet
• Curvilinear
• Micro Drawing
• Micro Molding
• Thermoplastic Forming
• Bulk Metallic Glass
• Surgical Blade

Statement dc:rights

• Copyright 2015 James Zhu

Handle dc:identifier

http://hdl.handle.net/2142/78289

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/78289