Date of Award

Winter 2013

Degree Type

Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

First Advisor

Yung C. Shin

Committee Chair

Yung C. Shin

Committee Member 1

Eric Kvam

Committee Member 2

Galen King

Abstract

Titanium alloys are well known for their excellent strength to weight ratio and corrosion resistance and is highly sought after in the aerospace industry. Additionally, titanium alloys maintain a high biocompatibility for implants and other medical devices. However, these alloys are notorious for their poor machinability. As the demand for these alloys continue to increase, improved methods of manufacture must be explored. ^ This thesis describes Laser Assisted Milling (LAML) of Ti-6AL-4V (Ti-64) alloys, which studies localized preheating of the workpiece by a laser and characterizes the improvements to the machinability of these metals. Laser parameters are determined based on temperature prediction modeling results. Laser preheating is shown to reduce cutting force during the machining process. Machinability improvement is characterized through inspection of flank wear on the cutting tool using LAML and traditional machining methods and comparing total tool life. Systematic characterization of samples is performed using hardness measurements, scanning electron microscopy (SEM), and X-ray diffraction (XRD) to ensure that material properties remained unaltered as a result of laser preheating. ^ An economic analysis is performed to characterize the cost benefit of machining using LAML while considering the additional costs associated with the laser equipment. Economic improvements are shown for the LAML process for Ti-64 alloys. A rotary axis is added to the machining equipment to overcome design constraints from the laser setup and allow for the machining of complex shapes. The feasibility of complex contouring is demonstrated for LAML with the creation of more intricate geometry being performed on a titanium workpiece.

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