Advanced
Manufacturing
Choices
ENG 165-265
Spring 2014, Dr. Marc Madou
Class 2
3/22/2016
Table of Content
• Manufacturing types: Primary, secondary and
tertiary manufacturing
• Mechanical machining definition
• Recognized categories of mechanical
machining: turning, milling, drilling and
grinding.
• CNC machining
• Precision machining
• Ultraprecision and nanotechnology
• Desk top factory (DTF)
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Manufacturing Types
• Manufacturing dominates world trade. It is the main wealth
creating activity of all industrialized nations and many
developing nations. A manufacturing industry based on
advanced technologies with the capability of competing in
world markets can ensure a higher standard of living for an
industrial nation (McKeown, 1996).
• Where primary manufacturing processes involve casting* and
molding**, secondary manufacturing processes constitute the
main mechanical removing techniques involving turning,
drilling and milling. Abrasive processes to super-finish a workpiece are called tertiary manufacturing processes.
Casting*/molding**: The act or process of making casts or impressions, or of
shaping metal or plaster in a mold; the act or the process of pouring molten metal
into a mold.
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Manufacturing Types
• The difference between casting
and molding is that in
"traditional" casting processes,
the mold is destroyed/
consumed when removing the
work-piece from it while in
molding, the mold is re-used
multiple times(this difference is
not often respected in naming
different processes).
• Lost wax casting process: see
video
• Sand casting: see utube
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Mechanical Machining
• In mechanical removal processes, stresses induced by
a tool overcome the strength of the material.
• The process produces complex 3D shapes, with very
good dimensional control, and good surface finishes.
• The method is wasteful of material, and expensive in
terms of labor and capital.
• How well a part made from a given material holds its
shape with time and stress is referred to as the
dimensional stability of the part and the material.
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Mechanical Machining
• To maximize dimensional stability, the machine design
engineer tries to minimize the ratios of applied and
residual stress to yield strength of the material.
• A good rule of thumb is to keep the static stress below 10
to 20% of yield strength.
• Increased heat at the work-piece causes uneven
dimensional changes in the part being machined, making
it difficult to control its dimensional accuracy and
tolerances. Thermal errors are often the dominant type
of error in a precision machine, and thermal
characteristics such as thermal expansion coefficient and
thermal conductivity deserve special attention .
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Mechanical Machining
• In mechanical subtractive machining, physical removal of
unwanted material is achieved by mechanical energy applied
at the work piece.
• Mechanical material removing technologies are also
categorized as single point machining or abrasive machining
i.e., multi-point machining.
• Mechanical removal processes can be broken down into four
commonly recognized categories: turning, milling, drilling and
grinding.
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First lathe as depicted in an Egyptian
bas relief; about 300 B.C. Shown here
in a line drawing. The man at left is
holding the cutting tool. The man at the
right is making the workpiece rotate back
and forth by pulling on a cord or thong.
Mechanical Energy Based Removing
• What is milling? The use of a rotating multi-point cutting tool
to machine flat surfaces, slots, or internal recesses into a
work-piece.
• Milling is one of the more versatile machining processes.
There are three degrees of freedom associated with milling.
The tool can move up and down, left to right, and front to
back. In this process the tool spins while the part remains
stationary. Although milling is a more versatile process than
turning or grinding, it is not as accurate and tends to leave a
rougher surface finish than the other two processes.
• What is turning ? Turning is the machining operation that
produces cylindrical parts. In its basic form, it can be defined
as the machining of an external surface with the work-piece
rotating and with a single-point cutting tool.
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Mechanical Energy Based
Removing
• The main difference between turning and milling is that in
turning the work-piece spins while the tool remains
stationary. Because of this, turning can be used to create a
great surface finish on cylindrical parts.
• Turning is done on a machine called a lathe. The lathe spins
the workpiece, while the lathe operator can position the tool
to remove the material. The work-piece is held in the chucks
of the lathe.
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Mechanical Energy Based Removing
• Drilling can be defined as a rotary
end cutting tool having one or
more cutting lips, and having one
or more helical or straight flutes
for the passage of chips and the
admission of a cutting fluid.
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Mechanical Energy Based Removing
• Grinding is a finishing process that is used to remove
surplus material from the work-piece surface. It is
usually used on almost any surface that has been
previously rough machined and is among the most
expensive process for it is generally quite slow in
removing material.
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Mechanical Energy Based Removing
• By 1977, highly precise instruments such as
servomotors, feedback devices, and computers were
implemented, paving the way for computer
numerical control machining, commonly called CNC
machining, which is now standard in many types of
machine shops. At the start, the smallest movement
these machines could reproducibly make was 0.5
µm.
• The resolution of the steps a machine can make, of
course, is a determining factor for the
manufacturing accuracy of the work-piece.
• Numerical control is a method of automatically
operating a manufacturing machine based on a code
of letters, numbers, and special characters.
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Mechanical Energy Based Removing
• Point-to-point control systems cause the tool to move
to a point on the part and execute an operation at
that point only. The tool is not in continuous contact
with the part while it is moving.
• Continuous-path controllers cause the tool to
maintain continuous contact with the part as the tool
cuts a contour shape.
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Mechanical Energy Based Removing
• These continuous
operations include
milling along any lines
at any angle, milling
arcs and lathe turning.
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Mechanical Energy Based Removing
• CNC milling machines
can perform
simultaneous linear
motion along the three
axis and are called
three-axes machines.
• More complex CNC
machines have the
capability of executing
additional rotary
motions (4th and 5th
axes).
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Vertical
milling
machine
Right hand
rule
Mechanical Energy Based Removing
• Machining Centers, equipped with automatic tool changers,
are capable of changing 90 or more tools. Can perform
milling, drilling,boring* turning, … on many faces. * Boring is
the process of using a single-point tool to enlarge a preexisting hole.
• Process flow:
–
–
–
–
–
–
–
Develop or obtain the 3D geometric model of the part, using
CAD.
Decide which machining operations and cutter-path directions
are required (computer assisted).
Choose the tooling required (computer assisted).
Run CAM software to generate the CNC part program.
Verify and edit program.
Download the part program to the appropriate machine.
Verify the program on the actual machine and edit if
necessary.Run the program and produce the part.
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Mechanical Energy Based Removing
• In an integrated CAD/CAM
system, the geometry and
tool motions are derived
automatically from the CAD
database by the NC program
(Pro/E, Unigraphics, ….)
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CNC milling is a cutting process in which material is removed
from a block of material by a rotating tool using a computer
numerically controlled program or code to achieve a desired
tool path to machine very accurate parts precisely and efficiently.
Precision Machining
• Mechanical engineers define precision machining as machining in
which the relative accuracy (tolerance/object size) is 10–4 or less of a
feature/part size
• For comparison, a relative accuracy of 10–3 in the construction of a
house is considered excellent. It is important to realize that, while IC
techniques and silicon micro- and nano-machining can achieve
excellent absolute tolerances, relative tolerances here are rather
poor compared to those achieved by most mechanical machining
techniques.
• The decrease in manufacturing accuracy with decreasing size is rarely
mentioned in discussions of Si micro-machines; this probably is
because Si micromachining originated from electrical engineering
practice rather than mechanical engineering.
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Precision Machining
• In the 1980s advanced machine tools became equipped with
precision metrology and control tools. These machines used
laser interferometer and capacitance probe feedback
controls, temperature control and hydrostatic bearings, and
featured accuracies better than 0.1 micrometers. Precision
manufacturing methods were extended for industrial use for
cutting aluminum, which was used for making components for
scanners, photocopying machines and computer memory
disks. Also in the 1980s, cutting with very small diamond tools
(e.g., 22 µm diameter) was developed in Japan.
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Ultra Precision MachiningNanotechnology
• Taniguchi coined the term
nanotechnology and in 1974, used
the term to define ultra-precision
machining.
• Taniguchi defines ultra-precision
machining as “the process by
which the highest possible
dimensional accuracy is achieved
at a given point in time.”
• Norio Taniguchi predicted
accuracies along with the
processes or tools used to achieve
it (next page)
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Norio Taniguchi (谷口紀男) (27 May 1912 - 15 November 1999)
was a professor of Tokyo Science University.
Precision and ultra-precision machining
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Ultra Precision MachiningNanotechnology
• By 1993, 0.05 µm became possible,
and today there is equipment
available featuring 0.01 µm and even
nanometer step resolution 10
(http://www.fanuc.co.jp/eindex.htm
).
• This evolution closely follows the
predictions sketched in the Taniguchi
curves showing a machining accuracy
for ultra-precision machining of subnanometer resolution for the year
2008 (see previous slide) .
• Fanuc’s the ROBOnano Ui an ultraprecision micromachining station (cost
1 $ million) and a Noh mask made
with this machine
(http://www.fanuc.co.jp/en/product
/robonano/index.htm).
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Desk top factory
• The fact that it often takes
a two-ton machine tool to
fabricate micro parts, where
cutting forces are in the
milli- to micro-Newton
range is a clear indication
that a complete machine
tool redesign is required for
the fabrication of micromachines.
• One approach is the desktop factory.
Commercial desktop factories (DTFs) at Sankyo Seiki.
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Desk top factory
• Desktop factories (DTF) constitute a rather interesting new manufacturing
philosophy involving flexible and modular table-top-sized automated
factories that feature minimal human participation in the manufacturing
process.
• An example of such a factory is shown below. Since the early nineties
progress has been made towards making such desktop factories (DTF) a
reality. A desktop factory as shown here has the potential of becoming the
factory of the future: a totally self-contained, robotic, desktop-size
machine tool that only requires materials, power and water as outside
inputs, and out come the finished machined products. The first R&D
desktop factories incorporated lathes, cleaning, gluing, punching and
drilling stations. The workpiece is transported between these different
machining functions by a “cart” moving from station to station.
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Desk top factory
• An example of a
desktop factory at
AIST, Japan.
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