Ultrasonic machining is a non-traditional machining process that uses high-frequency vibrations delivered to an abrasive tool tip to accurately machine hard and brittle materials without inducing stresses. The tool vibrates at 20-100 kHz with an amplitude of 0.025 mm while submerged in an abrasive slurry, and material is removed through micro-chipping as the abrasive particles are driven between the tool and workpiece. Ultrasonic machining works well for materials like aluminum oxides, silicon, glass, and ceramics that are difficult to machine through traditional methods.

1. Dr. S. & S.S. Ghandhy
College of Engg. &
Tech.
Ultrasonic MachiningUltrasonic Machining
Department of Mechanical Engg.
By VAIBHAV TAILOR

2. Ultrasonic Machining(USM)
• Ultrasonic machining is a non-conversational
machining process.
• high-frequency vibrations delivered to a tool tip,
embedded in an abrasive slurry, by a booster,
create accurate cavities of virtually any shape.
• Since this method is non-thermal, non-electrical,
and non-chemical, it produces virtually stress-
free shapes even in hard and brittle work-pieces.

3. Machine for USM

4. Ultrasonic Machining(USM)
• Ultrasonic Machining is most
effective for hard and brittle
materials; soft materials
absorb too much sound
energy and make the process
less efficient.
• Almost any hard and brittle
material, including aluminum
oxides, silicon, silicon carbide,
silicon nitride, glass, quartz,
sapphire, ferrite, fiber optics,
etc., can be ultrasonically
machined.

5. Ultrasonic Machining(USM)
• Conversely, mechanical
vibrations are obtained by
applying electrical
oscillations to the same
crystals. Ultrasonic waves are
sound waves of frequency
higher than 20,000 Hz.
• The tool, typically vibrating at
a low amplitude of 0.025 mm
at a frequency of 20 to 100
kHz, is gradually fed into the
work-piece to form a cavity
corresponding to the tool
shape.

6. Ultrasonic Machining(USM)
• The vibration transmits a high velocity force to fine
abrasive grains between the tool and the surface of the
work-piece. In the process material is removed by micro-
chipping or erosion with the abrasive particles.
• The grains are in a water slurry which also serves to
remove debris from the cutting area. The high-frequency
power supply for the magneto-strictive or piezoelectric
transducer stack that drives the tool is typically rated
between 0.1 and 40 kW.

7. Ultrasonic Machining(USM)
• The mechanical properties
and fracture behavior of the
work-piece materials also
play a large role in both
roughness and cutting
speed. For a given grit size of
the abrasive, the resulting
surface roughness depends
on the ratio of the hardness
(H) to the modulus of
elasticity (E). As this ratio
increases, the surface
roughness increases.

8. Process Parameters for USM
• Amplitude of vibration – 15 – 50 μm
• Frequency of vibration – 19 – 25 kHz
• Feed force – related to tool dimensions
• Feed pressure
• Abrasive size – 15 μm – 150 μm
• Abrasive material – Al2O3 - SiC - B4C - Boronsilicarbide -
Diamond
• Flow strength of work material
• Flow strength of the tool material
• Contact area of the tool – A
• Volume concentration of abrasive in water slurry – C

9. Application of USM
• Used for machining hard and brittle metallic
alloys, semiconductors, glass, ceramics, carbides
etc.
• Used for machining round, square, irregular
shaped holes and surface impressions.
• Machining, wire drawing, punching or small
blanking dies.

10. Limitation of USM
• Low MRR .
• Rather high tool wear .
• Low depth of hole .