1. Faculty of Engineering
Alexandria University
Investigation into Friction Drilling Process
By
Mohamed Alaa El-Dakrory
A thesis submitted to the
Production Engineering Department
in partial fulfilment of the requirements
for the degree of
Master of Science
Supervisors
Prof. Dr. Mohammad Yahya Al-Makky
Dr. Mohamed Abdelmoneim Daha
2. 1. Introduction to Friction Drilling
2. Thermal Friction DrillingTooling System
3. Finite Element Modeling of Friction Drilling
4. Experimental Setup
5. Results and Discussion
6. Conclusions
4. 4
Friction drilling is a hole making operation that is
based on a combination of axial force and relatively
high speed that generates local heat through friction
to penetrate and deform the work material into a
bushing shape.
5. a) The tip of the conical tool approaches and contacts
the workpiece
b) Friction on the contact surface, created from axial
force and relative angular velocity between tool
and workpiece, produces heat and softens the
workpiece material
c) The tool initially pushes the softened work-material
sideward and upward, then the tool pierce through
the workpiece
d) The tool moves further forward to push aside more
workpiece material and form the bushing using the
cylindrical part of the tool
e) The shoulder of the tool may contact the workpiece
to collar the back extruded burr on the bushing
5
7. Friction drilling makes a hole with a bushing length
that is 2 to 3 times the original sheet thickness in a
single step.
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8. No material is removed during thread forming. The process
displaces the material to generate the thread
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9. Different tool geometry
Higher heat generated and higher power consumption
Workpiece volume is constant
Small sheet thicknesses only (up to 12 mm).
Higher rotational speeds are required
TFD has an effect on friction drilled hole microstructure due
to heat
Chip-less process
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13. Reduced material waste. All material from the drilled hole is
transformed to create the bushing.
Reduced inventory costs
13
Wide variety of Materials can be drilled
A single cycle operation suitable for
automated manufacturing
No disturbances caused by chips
14. The target material must be able to withstand the
added heat
not possible in massive material.
Not suitable for painted or coated materials
Small thicknesses only
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18. Uniform tool with 100% friction contact area
Polygon tool with triangle, square or pentagon cross section so
that the friction contact area will vary 30%,50% or 75%
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19. The tool holder holds the following:
Transmission shaft,
Cooling Disk,
Collet and a nut
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21. Miller, et. al. (2012) Investigated the effect of
different parameters on cutting forces and torque.
Fernández et. al. (2013) analyzed, through controlled
tests at different rotational speeds and feed rates,
the friction drilling of austenitic stainless steel with
different thicknesses
Somasundaram (2011) applied response surface
methodology to develop a mathematical model for
hole quality in terms of roundness error
21
22. Miller S.F., Blau P.J. and Shih A.j characterized the micro-
structural alterations and subsurface micro-indentation
hardness changes produced as a result of the friction
drilling.
Miller S.F., TaoJ. and Shih A.J. [4] needed to generate a
cylindrical shaped bushing without significant radial
fracture or petal formation in brittle cast aluminum.
Miller S.F., Li R., Wang H. and Shih A.J. studied the wear of
carbide tool used for friction drilling of AISI 1015 steel
workpiece.
Lee S.M., Chow H.M., Huang F.Y. and Yan B.H. [10] used
tungsten carbide drills with physical vapor deposition
AlCrN andTiAlN coatings, and without coating to make
holes in AISI 304
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23. Miller S.F. and Shih A.J. [7] investigated 3D finite
element modeling for friction drilling of Al6061-T6
work-material.RESULT
Qu J. and Blau P.J. [9] developed a new model for
thermal drilling useful for predicting the effective
friction coefficient and shear stresses
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25. Introducing the process to the Egyptian local market
Manufacturing low cost tools
Investigate the effect of heat on the axial force,
torque , hole quality and materials microstructure.
25
26. Working on higher feed speeds and rotational speeds
is not always available,Thus working at lower speeds
and producing good quality holes is challenging
The cost of the tools and tool holders is very high, we
need to find an alternative.
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27. Tool manufacturing
DAQ
Measure force and moment for different materials
FEA
Microstructural analysis
Hole quality evaluation
27
Low cost FD system with optimized
processing parameters
28. Designing and fabrication of friction drilling tools and cooling disk to
be used in experimental work.
With the aid of DAQ system, preparing a measuring setup to
measure the axial force and torque during the operation.
Developing a Finite Element Model for performance evaluation to
enhance input parameters selection.
Investigating the effect of the process working conditions on the
axial force, torque, tools as well as the products quality, aiming to
introduce the process to the Egyptian industries.
based on design of experiments methodology, conducting statistical
experiments for three different materials, to investigate the process
parameters and to validate the finite element model.
Studying the microstructure of the drilled specimens and the
microhardness due to the heat generation during the process
Investigating the approach to introduce the friction drilling process
to the Egyptian industries
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29. 29
Property Material
Al 6061 St 1020 St.St.304
Yield Strength (Mpa) 274 294 215
Specific Heat Capacity J/g-°C) 0.896 0.519 0.5
Young’s Modulus (Gpa) 68.9 205 200
Poisson’s Ratio 0.33 0.29 0.29
ThermalConductivity (W/M-k) 167 51.9 16.2
30. 30
Effective Plastic Strain
Max.=3 mm/mm
Min.= 1 mm/mm
Temperature
Max.=308 Degree C
Min.= 20 Degree C
Effective Stress
Max.=680 MPa
Min.= 0 Mpa
42. Force Dynamometer Charge Amplifier DAQ Card
Model: KistlerType 9271 A
Force : Measuring range:
Fz: -5,000 N to 20,000 N
Sensitivity: 1.87 pC/N
Torque : Measuring range:
Mz : -1000 to 1000 Nm
Sensitivity: 1.62 pC/Ncm
Model: KistlerType :5017 B)
No. of channels: 8
Model: PCI-DAS 1602/16
12- bit A/D resolution.
330-kHz sample rate.
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43. Process
Parameter
Levels
1 2 3
Rotational Speed
(A)(r.p.m)
2000 2500 3000
Feed speed (B)
(mm/min)
0.1 0.2 0.3
W/P Material (C) 1100 Aluminum 1.0303 Steel 304 Stainless Steel
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The effect of three parameters; rotational speed (A), feed speed
(B), workpiece material (C) will be investigated .A full factorial
design of experiments 33 is chosen and each factor will have 3
levels; low level (level 1), medium level (level 2), and the high
level (level 3)
53. microstructure of the drilled holes is an important process aspects to be
investigated. Heat generated may reach up to 900 degrees Celsius in some
cases.
To get better surface finish the workpiece was submerged in epoxy to
increase the efficiency of the polishing process.
The specimens were chemically etched for microstructural observations.
Chemical etchants were applied to reveal the grain boundary and observe
the large plastic deformation of work-material
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64. It is essential to know the hardness values of the work
piece, as hardness is the property of a material that
enables it to resist plastic deformation, usually by
penetration
The testing samples were tested byVickers hardness
tester.The hardness of the drilled material was
changing in dependence of measuring distance from
the heat influenced places
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65. A 2mm step was taken from the hole edge to
investigate the effect of heat on the microhardness
along the hole edge and away from the hole edge
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68. Deficiencies in the bushing or the collar quality will affect the
thread forming operation and the thread dimensions.
Radial drilling forces and hear generated may have a
significant effect on the collar quality,
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69. 0.1 mm/sec 0.2 mm/sec 0.3 mm/sec
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• At low rotational speed (2000 rpm) the formed collar was
ruptured with rough surface due to high friction
70. • Depending on the increase in drilling rotational speed, the fast
decrease in radial forces made sure that a smooth washer is
formed due to less effect on washer geometry
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0.1 mm/sec 0.2 mm/sec 0.3 mm/sec
71. Another aspect to be considered when studying the
hole geometry of friction drilled holes is bushing
formation
According to Flowdrill Company [2], the generated
bushing in friction drilling is assumed to be 2 or three
times the original sheet thickness
The process main goal is to obtain as long bushing as
possible because this bushing will be used in
threading
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72. 78
Effect of Rotational speed on bush length (2000 rpm, stainless steel)
• At lower speeds the heat generated is not enough to
decrease the yield strength of the material and so, the
bushing length is shorter. Also radial force increases
depending on higher axial force due to low temperatures.The
increase in radial force ruptures the edges of the hole and
increases petal during the formation of bushing.
73. At high speeds the heat generated increases which
means that the yield stress of the workpiece
decreases and material suffers less deformation thus,
the extrusion length increases
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75. Friction drilling can be performed at low feed speeds
ranges (0.1- 0.3 mm/sec)
Feed speed has greater influence on the cutting forces
than rotational speeds for the investigated range.
In friction drilling, not only the material hardness and
carbon content can affect the force values, but also the
material thermal properties.The force required to drill
Stainless steel is lower than that of 1.0303 Steel, the main
reason for this phenomenon is the thermal conductivity
of both materials (75 wm-1k-1 for Steel and 17.6 wm-1k-1
for Stainless steel) which means that Stainless steel will
not dissipate heat easily, which in return will decrease the
required drilling forces.
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76. Although Stainless steels are considered hard-to-machine
materials, with respect to friction drilling , 304 Stainless
steel needs lower forces to be drilled because of its high
formability
Friction Drilling has large influence on the microstructure
of the drilled holes. In most cases finer grains are
produced as a result of normalization.
The microhardness of most specimens has increased after
friction drilling as a result of the new fine grains structure.
Locally manufactured tools are cost effective and can
perform friction drilling and produce good quality holes.
However, the main limitation was the tool lifetime which
was very short compared to Flowdrill tool
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77. Better finite element model with improved accuracy can
be developed with an emphasis on simulating the effect
of heat on microstructure alterations.
Effect of preheating the workpiece before drilling needs
to be observed as it may decrease the drilling forces and
improve the hole quality
Drilling brittle materials is challenging and needs to be
investigated
Manufacturing of friction drilling tools with longer tool
life
Correlating the effect of sheet thickness to the ratio
between the hole diameter and bushing length. (d/t).
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