Poster Template

1
Improving Machinability of Difficult-to-Cut
Advanced Aerospace Materials Through High-Speed
End-Milling
Faculty Advisor Dr. A.C. Okafor, Mechanical and
Aerospace Engineering
Student Emenike Chukwuma (M.Sc candidate),
Mechanical and Aerospace Engineering

• Objectives
• To improve the machinability and productivity of
  end milling of difficult-to-cut advanced
  aerospace materials through high speed machining
  and application of different cooling and
  lubrication strategies.
• To investigate the effects of cooling and
  lubrication strategy on tool wear, surface
  integrity and temperature

Discussion High Speed Machining (HSM) is defined
as machining process using spindle speeds
greater than 7,000rpm and feedrates greater than
100 meters per minute for aluminum. The current
industrial standard for machining titanium, here
after referred to as baseline parameters, are
spindle speed of 153 rpm (50 fpm) for roughing
with HSS-Co and spindle speed of 2037 rpm (400
fpm) for finishing using solid carbide end-mill.
Therefore any speed above this baseline parameter
for titanium is regarded as High Speed Machining.
HSM is an emerging technology that offers
significant potential for fabricating large
intricate and delicate structural components and
hardened materials faster and accurately,
especially for the aerospace industry. It results
in greater material removal rates, lower cutting
force, especially when enhanced with an effective
cooling and lubrication strategy, thus
improvement in productivity. However a lot of HSM
issues are not well understood by airframe and
automotive manufacturers.
Background Titanium alloy, Nickel-based alloy,
and Inconel 718 are attractive materials in
various key industries due to their excellent
combination of strength to weight ratio
maintained at high temperature, and resistance to
corrosion and fracture but they are classified as
difficult-to-cut materials due to their low
thermal conductivity, low modulus of elasticity
and high chemical reactivity End-milling is a
type of milling process most commonly used for
metal removal in aerospace and automotive
industries for making prismatic and monolithic
parts. Cutter breakage, high cutting forces,
high cutting temperature, and rapid tool wear ,
and accuracy of machined parts , vibration and
chatter are the major problems experienced with
end milling process. Application of lubricants
and coolants in cutting processes play very
important roles including increase in tool life
and dimensional accuracy, decrease in cutting
temperatures, surface quality improvement and
reduction in cutting force/power consumed during
machining . Conventional coolants are more
costly, ineffective and create some
techno-environmental problems such as,
environmental pollution due to chemical
dissociation or break up due to high cutting
temperature. So, it is absolutely necessary to
use an environmentally acceptable cooling and
lubrication strategies in manufacturing industry.
Concluding Remarks This research work hopes to
improve the structure and properties of
machined difficult-to-cut metals and alloys,
thereby increasing tool life while maintaining an
industrially acceptable surface finish and
surface integrity.
Chips from end-milling Titanium Alloy
Future Work Our current approach to end milling
of difficult-to-cut aerospace materials may be
extended to machining of advanced composite
materials used for the same industrial
applications.
Approach All machining experiments will be
conducted on Cincinnati Milacron, Sabre 750
vertical machining center equipped with Acramatic
2100 controller, using a five-flute solid carbide
end-mill tool sized 0.5inch diameter. Surface
roughness will be measured with profilometer,
tool wear will be measured with tool makers
microscope, temperature of the workpiece will be
measured with an embedded thermocouple probe in
the workpiece and cutting force will be acquired
with a 4-component Kystler dynamometer model.
Acknowledgements Support from Dr. Okafors
National Science Foundation grant and that from
Intelligent Systems Center is greatly
acknowledged.
Machining set-up after end-milling Titanium alloy