ultra sonic machining

1. Non Traditional Machining
Processes (NTP(
Prof. Dr. Taha Ali El-Taweel
Professor of manufacture engineering
Faculty of Engineering, Menofiya University

2. Ultrasonic
machining (USM)

3. Ultrasonic machining (USM(
Principle of USM
Ultrasonic machining (USM(
is the removal of hard and
brittle materials using an
axially oscillating tool at
ultrasonic frequencies [18–20
kHz]. During that oscillation,
the abrasive slurry is
continuously fed into the
machining zone between a
soft tool and the workpiece.
The abrasive particles are,
therefore, hammered into the
workpiece surface and cause
chipping of fine particles from
it.

4. The machining system
The machining system is
composed mainly from:
 magnetostrictor,
 concentrator,
 tool, and
 slurry feeding arrange.
The magnetostrictor is
energized at the ultrasonic
frequency and produces
small-amplitude vibrations.

5. Magnetostriction
The magnetostrictor
used in USM has a
high-frequency
winding wound on a
magnetostrictor
core and a special
polarizing winding
around an armature.
Magnetostrictor material converts the magnetic energy
to a mechanical one.

6. Coefficient of magnetomechanical coupling:
Ew is the mechanical energy
Em is the magnetic energy.

7. Variation in a wave of elongation along the length of
the magnetostrictor

8. Mechanical amplifier
The elongation from
magnetostrictor of
length of l = 0.5λ are
0.001-0.1µm.
USM required 0.01mm,
can be obtained from
“concentrator”
Types:
• Cylindrical
• Stepped
• Conical
• Exponential
• Hyperbolic

9. Materials for the tool
• Tool tips must have high wear resistance and
fatigue strength.
• Tungsten carbide, Copper, and Silver steel
Abrasive suspension
Abrasive slurry is usually composed of 50 percent
(by volume) fine abrasive grains (100–800 grit
number) of boron (B4C), aluminum oxide (Al2O3),
or silicon carbide (SiC) in 50 percent water.

10. Slurry injection methods
The slurry is continuously fed to the machining
zone in order to ensure efficient flushing of
debris and keeps the suspension cool during
machining.

11. Mechanism of material removal
The material is removed in the form of grains by:
- Shear deformation
- Brittle fracture of work material
- Impact
- Cavitation erosion
- Chemical reaction

12. Material Removal Rate (MRR)
Relative machinability ratings for some materials

13. Factors affecting USM
performance

14. Amplitude of tool vibration
Effect of process condition on MRR

15. Amplitude of tool vibration

16. Effect of grain size

17. Effect of cocentration and hardness

18. Effect of concentration and hardness

19. Effect of impact hardness of W.P material
H=F/4hd
H: w.p. material hardness (Brinell number)
d: the diameter of the embedded sphere
F: the force applied
h: the impact indentation depth

20. Effect of tool and w.p. on impact with grain
δt
+δw
= (d-x)
δt
, δw
: tool and w.p. indentation
x: distance separating them
y= ao
sinθ, δt
+δw
= ao
- ys
ys
: distance moved down by the tool from mean position

21. The rad. of of inden. on w.p.
rw
= [δw
d]1/2
Fracture /grit
Vo
= 2/3π[δw
d]2/3
Fc
: the contact load
δw
/d<<1
Hw
=Fc
/πδw
d
Fc
= π d Hw
δw
Hw
/ Ht
= δw
/δt
=q
δw
= (d-x)/(1+q)

22. Effect of shape of the tool

23. Effect of static load

24. Effect of static load

25. MRR

26. SURFACE FINISH

27. » Micro-hole drilling» Micro-hole drilling
The entrance The exit
Micro air turbine.Center
pin diameter 70 µm;
rotor diameter 350 µm
Finishing
» Manufacturing of 3D s
tructures
» Manufacturing of 3D s
tructures
» Finishing EDMed parts» Finishing EDMed parts
USM applications

28. THANK YOU!!