Ultrasonic machining is a non-traditional machining process that uses abrasive particles suspended in a liquid slurry and high frequency mechanical vibrations to erode material from a workpiece. It can machine hard and brittle materials regardless of their electrical conductivity. The process involves holding an abrasive tool against the workpiece under pressure with vibrations in the 20 kHz range. Process parameters like amplitude, frequency, feed force, and abrasive size influence the material removal rate and surface finish. Ultrasonic machining is capable of producing complex shapes like round, square and irregular holes with high aspect ratios and tolerances as small as 7 microns.

1. Indian Institute of Technology Roorkee
Topic : Ultrasonic Machining
Class : B-Tech 3rd Year
Production & Industrial
Subject : Communication Skills

2. Schematic view of an ultrasonic machining operation
Source: https://www.google.co.in/search?q=Ultrasonic+machining+images&es_sm=93&source=lnms&tbm=isch&sa= &ei=hfYWVNHZMZaiugSi5IKIAw&ved=0CAgQ_AUoAQ&biw=1280&bih=675

3. Source: IIT Kharagpur module 9 Non-conventional machining lesson 36 pdf
Figure:
Figure: Figure:

4. Mechanism
Source: http://www.bullentech.com/ultrasonic-machining

5. Various work samples machined by USM
Square, round and
oddshaped thru-
cuts in alumina.
Square cavities, round thru
holes and crossing beams in a
4-in. borosilicate wafer.
A Ummachined square hole
in 0.0175-in. thick glass. The machined
feature exhibits a clean edge, and the
natural corner radius is < 0.005 in.
Honeycomb structure
machined on the
back of a silicon
mirror for NASA.
Source: http://www.ceramicindustry.com/articles/ultrasonic-machining (8/29/2014)

6. PROCESS PARAMETERS-
• Amplitude of vibration (ao) – 15 – 50 μm
• Frequency of vibration (f) – 19 – 25 kHz
• Feed force (F) – related to tool dimensions (static loading)
• Feed pressure (p)
• Abrasive size – 15 μm – 150 μm
• Abrasive material – Al2O3 , SiC , B4C , Boronsilicarbide ,Diamond
• Hardness ratio of the tool and the workpiece
• Concentration of abrasive in the slurry (water)
• Contact area of the tool – A
Source: IIT Kharagpur module 9 Non-conventional machining lesson 36 pdf

7. The process parameters in USM affecting the qualities of the
machined surface can also be shown through the Ishikawa
cause-effect diagram:
Source: Effect of process parameters on MRR, TWR and surface topography in ultrasonic machining of alumina–zirconia ceramic composite Original Research Article Ceramics International, Volume 40,
Issue 8, Part B, September 2014, Pages 12831-12836 Shrikrushna B. Bhosale, Raju S. Pawade, P.K. Brahmankar

8. Effect of machining parameters on MRR
• mmr decreases when static force F gets high enough to crush abrasive grains.
Figure: Variation of material removal rate with feed force, frequency, amplitude
Source: Ghosh, A., Manufacturing Science, Ellis Horwood Ltd., Chichester, UK, 1986

9. http://engineeronadisk.com/V3/engineeronadisk-86.html
(9/2/2014)
Figure: Variation of feed force with time
Figure: Variation of material removal rate with
feed rate and hardness ratio
Source: Ghosh, A., Manufacturing Science, Ellis Horwood Ltd., Chichester, UK, 1986

10. Figure: Dependence of material removal rate on grain diameter, concentration, viscosity and effect of
grain size on surface finish.
Source: Ghosh, A., Manufacturing Science, Ellis Horwood Ltd., Chichester, UK, 1986

11. Table 1- Relative material removal rates
Source: Ghosh, A., Manufacturing Science, Ellis Horwood Ltd., Chichester, UK, 1986

12. Source: Effect of process parameters on MRR, TWR and surface topography in ultrasonic machining of alumina–zirconia ceramic composite Original Research
Article Ceramics International, Volume 40, Issue 8, Part B, September 2014, Pages 12831-12836 Shrikrushna B. Bhosale, Raju S. Pawade, P.K. Brahmankar

13. PROCESS CAPABILITIES-
Properties Range
Works satisfactorily When workpiece hardness >HRC40
Holes (round, square and odd-shaped thru-holes) as small as 0.076 mm
Holes depth upto 51 mm
Aspect ratio 40:1
Penetration rate 0.025-25.0 mm/min
Surface finish 0.25 µm-0.75 µm
Tolerances 7µm-25µm
Conductivity USM is capable of machining any materials regardless
of their conductivity.
No abnormal surface USM does not produce any abnormal surface due to
electric, thermal, and chemical effects.
Source: xa.yimg.com/kq/groups/24347222/1876120766/name/unit11.pdf

14. Advantages 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.
• It is not affected by the electrical or chemical characteristics of the work material.
• It is used in machining small dies (wire drawing, punching or small blanking dies).
Disadvantages/Limitations of USM-
• Soft materials like lead and plastics are not suitable for machining by the USM process, since they
tend to absorb the abrasive particles rather than to chip under their impact.
• The USM process consumes higher power and has lower material removal rates compared to
traditional fabrication processes.
• Tool wear is high and sharp corners cannot be produced.
• Tool lateral sides becomes tapered and sharp corners get rounded as machining continues so
accurate blind holes cannot produced.
• Cost of machining is high.

15. References
• http://en.wikipedia.org/wiki/Ultrasonic_machining
• Google Images
• http://engineeronadisk.com/V3/engineeronadisk-86.html (9/2/2014)
• Ghosh, A., Manufacturing Science, Ellis Horwood Ltd., Chichester, UK, 1986.
• Manufacturing Technology Volume 2-Metal Cutting and Machine Tools, P N RAO
• P.K. Mishra Non-conventional Machining (second edition)Narosa Publishing House (2000), pp. 22–42
• Effect of process parameters on MRR, TWR and surface topography in ultrasonic machining of alumina–
zirconia ceramic composite Original Research Article Ceramics International, Volume 40, Issue 8, Part
B, September 2014, Pages 12831-12836 Shrikrushna B. Bhosale, Raju S. Pawade, P.K. Brahmankar
• IIT Kharagpur module 9 Non-conventional machining lesson 36 pdf
• 8/29/2014 MICROCERTEC specialist of advanced ceramics : precision machining by diamond grinding and
ultrasonic machining, thin film metallising, brazed asse…
• http://www.bullentech.com/ultrasonic-machining
• http://www.ceramicindustry.com/articles/ultrasonic-machining (8/29/2014)
• xa.yimg.com/kq/groups/24347222/1876120766/name/unit11.pdf

16. THANK YOU