Design and fabrication of micro end mills for the machining of difficult-to-cut materials
Author
Oliaei, Samad Nadimi Bavil
Advisor
Karpat, Yiğit
Date
2016-09Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
Micromilling is a cost-e ective method of fabricating miniaturized components with
complex, three-dimensional features made from di cult-to-cut materials. Microcutting
tools are exposed to harsh conditions during machining of such materials,
which leads to short tool life and thus a ects the economics of the process.
The aim of this thesis is to develop a systematic approach to the design and fabrication
of high-precision micro-cutting tools. Machining characteristics of three di erent
di cult-to-cut materials–stainless steel, titanium alloy, and silicon–have been investigated
using experimental techniques. The results reveal the importance of interaction
between tool micro geometry and work material mechanical properties. This observation
leads to the development of tailored micro-end mills which are designed and
fabricated based on the requirements of the specific machining task.
This study also examines in detail built-up edge, an important but usually overlooked
issue in micromachining of ductile materials, which a ects the process forces,
tool wear, and tool deflections. The protective e ect of built-up edge has been exploited
by creating micro-dimples on the tool surface using electrical discharge machining.
Its positive influence on tool performance has been demonstrated. As for
the micromachining of silicon, the flow of cut material around the cutting edge is
paramount in tool design. A novel tool design for machining of silicon has been proposed
and its e ectiveness has been validated through experiments.
It has been shown that the selection of proper process parameters together with
tailored tool design may increase the productivity of micromachining and improve
surface quality and dimensional accuracy of micro-scale parts.