METAL CUTTING from Science to Art

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METAL CUTTING from Science to Art

• Ranga Komanduri
• Oklahoma State UniversityStillwater, OK

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ACKNOWLEDGMENTS

• National Science Foundation
• DARPA, EPA, OSU
• A. H. Nelson, Jr. Endowed Chair in Engineering
• Teachers, professional colleagues, and students

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DEDICATION

• This lecture is respectfully dedicated to the
  pioneers around the world in the science and art
  of manufacturing processes.

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Count Rumford (1798)

• Rumford conducted a systematic analysis of heat
  generated in the boring of a cannon to inquire
  into the source of heat excited by friction. He
  was fascinated by the heat acquired by a brass
  cannon in a short time and with the still more
  intense heat of the metallic chips.
• Thompson, B., An Enquiry Concerning the Heat
  Which is Excited by Friction, Phil. Trans. Royal
  Soc. (Lon) (1798) 278-287

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J. P. Joule (1850)

• That justly celebrated natural philosopher
  demonstrated by his ingenious experiments that
  the very great quantity of heat excited by the
  boring of the cannon could not be ascribed to a
  change taking place in the calorific capacity of
  the metal. It appears to me extremely difficult
  to form any distinct idea of anything, capable of
  being excited and communicated in these
  experiments except it be motion.
• On the Mechanical Equivalent of Heat, Phil
  Trans. Royal Soc. (Lon) (1850) 61-81

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Joule On the Mechanical Equivalent of Heat

• Referring to Rumford article, Joule states One
  of the most important part of the paper to which
  little attention has been paid, is the estimation
  he made of the quantities of mechanical force
  required to produce a certain amount of heat.
  This result is not very different from that which
  I deduced from own experiments viz. 772 ft-lbs

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Schmidt and Roubik (1949)

• Distribution of Heat Generated in Drilling

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Mallock (1881)

• The Action of Cutting Tools, Proc. Roy. Soc.
  (Lon) 33 (1881) 127-139

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F. W. Taylor (1907)

• Taylors Tool Life Equation
• VTn C
• where V is the cutting speed and T is the tool
  life in min.
• Taylor, F. W.,On the Art of Cutting Metals,
  Trans ASME 28 (1907) 31-248

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Merchants Circle (1944)

• Basic Mechanics of the Metal Cutting, Trans
  ASME 66 (1944) A65-A71

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SUPER LATHE
Dont blame the ceramic tools, blame the machine
tools. - Jack Binns (1964)
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CONTRIBUTIONS TO THERMAL ANALYSIS

• Rosenthal's moving heat source and the moving
  coordinate system (1945)
• Blok's heat partition method (1937)
• Jaeger's heat source method (1942)

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THERMAL ANALYSISOF METAL CUTTING

• Hahn used an oblique shear plane heat source
  moving in the direction of cutting at the
  velocity of cutting. This approach does not
  require a priori, the assumption of heat
  partition between the work material and the chip
  but results as an output
• Chao and Trigger pointed out the importance of
  variable heat partition at the interface between
  the stationary tool and the moving chip.

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THEORY Vs. EXPERIMENT

• A theory is something nobody believes, except
  the person who developed it. An experiment is
  something everybody believes, except the person
  who conducted it.
• (attributed to) Albert Einstein

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THEORY Vs MODEL

• A theory has only the alternative of being right
  or wrong. A model has a third possibility it may
  be right but irrelevant.
• --- Manfred Eigen

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MATHEMATICAL SUPERIORITY

• In most sciences one generation tears down what
  another has built, and what one has established
  another undoes it. In mathematics alone each
  generation builds a new story to the old
  structure.
• -- Hermann Hankel

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FOR ANY PROBLEM THERE ARE THREE APPROACHES

• 1. Analytical,
• 2. Numerical, and
• 3. Experimental.

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ANALYTICAL METHODS

• Requires some simplifying assumptions to solve
  complex partial differential equations, such as
  quasi-steady state conditions, simple geometry
  and boundary conditions, constant thermal
  properties, etc.

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NUMERICAL METHODS

• while variable thermal properties with
  temperature can be incorporated in the simulation
  methods, the accuracy of these techniques are
  somewhat limited by the size of the grid and the
  distances between the nodes. While finer grid
  gives more accuracy, it can be at the expense of
  inordinate computational time, stability, and
  accumulated errors.

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EXPERIMENTAL METHODS

• experimental techniques are limited by the
  accuracy and limitations of the sensors and the
  instrumentation used.

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THEORY Vs. EXPERIMENT

• While experiment reveals the particular features
  of every process, the theory permits the
  establishment of the general laws and thus
  contributes to the fundamental knowledge of the
  process.
• --- Rosenthal

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SIMULATION OF MACHINING AT THE ATOMIC SCALE

• 1. Nanometric cutting of nonferrous materials,
  such as Cu and Al,
• 2. Effect of process parameters, such as, rake
  angle, edge radius, depth of cut on the cutting
  and thrust forces, force ratio, and specific
  energy,
• 3. Nanometric cutting of known crystal
  orientation of the workmaterials,
• 4. Milling
• 5. Nanometric cutting of semiconductor materials,
  such as silicon, and
• 6. Oblique machining.

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• Effect of Rake Angle

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Oblique Machining
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Oblique Machining
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• Great theoreticians know that hypothesis must be
  confirmed with experiment

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Einsteins Hot Time

• When a man sits with a pretty girl for an hour,
  it seems like a minute. But let him sit on a hot
  stove for a minute and its longer than any hour.
  Thats relativity.
• Einstein, A., On the Effects of External Sensory
  Input on Time Dilation, J of Exothermic Science
  and Technology 1, No.9, 1938.

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CONCLUSION

• The state of mind of the observer plays a crucial
  role in the perception of time

Mirsky, S., Einsteins Hot Time, Scientific
American (Sept. 2002), 102