1 Copyright © 2018 by ASME
Proceedings of the 2018 Manufacturing Science and Engineering Conference
MSEC2018
June 18-22, 2018, College Station, TX, USA
MSEC2018-6425
EDGE PROFILING OF TITANIUM ALLOYS AND ATTAINABLE SURFACE QUALITY
Liu Kui
Singapore Institute for Manufacturing Technology
73, Nanyang Drive, Singapore
Salman Pervaiz
Department of Mechanical
Engineering, Rochester Institute of
Technology, Dubai, UAE
Vincent Shantha Kumar
Department of Mechanical
Engineering, BITS Pilani- Dubai
Campus, UAE
Ram Karthikeyan
Department of Mechanical
Engineering, BITS Pilani- Dubai
Campus, UAE
KEYWORDS
Brushing, Abrasion, Deburring, Titanium
ABSTRACT
Machining operations such as reaming, boring or milling
create undesirable extruded sharp edges at the entry and exit side
of the machined holes. These sharp burrs / extruded edges act as
stress concentration regions for fatigue crack propagation in
safety critical aerospace components. In this paper, results of an
experimental investigation carried out on surface integrity of
titanium based alloy during mechanized edge profiling process
are presented. In the Mechanized Edge Profiling (MEP) process
the primary sharp edges created as result of hole machining are
removed using a hard point countersink tool and the secondary
sharp edges produced due to countersinking/chamfering the hole
entry and exit side edges are radiused using nylon impregnated
silicon carbide brushes. On-machine edge profiling experiments
were conducted using compliant Flexhone
TM
and Novoflex
TM
globular abrasive brushes on highly stressed bolt/flange holes.
Brushing speed and feed rate were identified as key process
variables. Nylon impregnated with silicon carbide 320 grit brush
showed good performance when brushing at a speed of 5000rpm
and 5000mm/min feed rate which produced a very consistent and
controlled secondary edge radius of 0.3±0.2mm up to 30 holes.
An acceptable surface roughness (Ra) of less than 0.5μm on the
chamfer and bore surfaces were achieved.
INTRODUCTION
Edge finishing is an important manufacturing process
carried out on key aero engine components that operate under
demanding conditions. Titanium based alloys are required to
increase the operational efficiency of gas turbine engines and
are material of choice for low and high-pressure compressor
components. Due to their superior material properties, chip
machining processes produce tough burr/edges that are still part
of the parent material. class 5 burrs are commonly known as
“extruded burrs” and are not actually burrs, but rather a
deformation of extruded material caused by drilling. They
appear as very large burrs that extrude from the base material.
The extruded or displaced material requires preconditioning
with a chamfer or carbide cutter to remove the material. The
resulting sharp corners could act as stress raisers and deteriorate
the surface integrity of the part thus affecting its fatigue life
significantly [1-3]. Preconditioning will leave the residual sharp
edge that is profiled with abrasive brushing. Hence, some form
of edge profiling operation is often defined to mitigate these
effects and such mitigation is highly critical in the aviation
industry where part failure resulting in inflight shut down is a
serious safety concern [4, 5]. Improving the performance of the
tools and developing an automated process to profile the edges
and defined edge modification are of considerable safety and
economic importance to the aviation industry.
Sathish Kannan
1
Department of Mechanical Engineering,
American University of Sharjah, U.A.E
1
Contact Author