Production Automation
Technologies
Henry C. Co
Technology and Operations Management,
California Polytechnic and State University
Evolution of Production
Technology
Year
Casting
Deformation
Joining
Machining
Ceramics
Plastics
4000 B.C.
Stone, clay
molds
Bending, forging
(Au, Ag, Cu)
Riveting
Stone, emery,
corundum,
garnet, flint
Earthenware
Wood, natural
fiber
2500 BC
Lost wax
(bronze)
Shearing, sheet
forming
Soldering,
brazing
Drilling, sawing
Glass beads,
potter's wheel
1000 BC
Hot forging
(iron), wiredrawing (?)
Forge welding,
gluing
Iron saws
Glass pressing,
glazing
0. A.D.
Coining (brass),
forging (steel)
Turning (wood),
filing
Glass blowing
1000
Wire drawing
Stoneware,
porcelain
(China)
1400
Sand casting,
cast iron
Water hammer
Sandpaper
Majolica, crystal
glass
1600
Permanent mold
Tinplate can,
rolling (Pb)
Wheel lathe
(wood)
1800
Flasks
Deep drawing,
rolling, (steel),
extrusion (Pb)
Boring, turning,
screw cutting
Plate glass;
porcelain
(Germany)
1850
Centrifugal,
molding
machine
Steam hammer,
tinplate rolling
Shaping, milling,
copying lathe
Window glass
from slit cylinder
Vulcanization
Year
Casting
Deformation
Joining
1875
Rail rolling,
continuous
rolling
1900
Tube rolling,
extrusion (Cu)
Oxyacetylene,
arc welding,
electrical
resistance
welding
Machining
Ceramics
Turret lathe,
universal mill,
vitrified wheel
Geared lathe,
automatic screw
machine,
hobbing, highspeed steel,
synthetic SiC,
Al2O3
Plastics
Celluloid, rubber
extrusion,
molding
Automatic bottle
making
1920
Die casting
W wire (from
powder)
Coated
electrode
Bakelite, PVC
casting, cold
molding,
injection
molding
1940
Lost wax for
engineering
parts, resinbonded sand
Extrusion (steel)
Submerged arc
Acrylics, PMMA,
P.E., nylon,
synthetic rubber,
transfer
molding,
foaming
1950
Ceramic mold,
modular iron,
semi-conductors
Cold extrusion
(steel)
TIG welding,
MIG welding,
electroslag
EDM
Plasma arc
Manufactured
diamond
1960
ABS, silicones,
fluorocarbons,
polyurethane
Float-glass
Acetals,
polycarbonate,
polypropylene
Production Automation Technologies (Henry C. Co)
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
Computer managed numerical control
(NC) is a generic term that
encompasses.

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Computer numerical control (CNC),
Direct numerical control (DNC), and.
Industrial robots.
Computer managed numerical control,
integrated with an automated material
handling and storage system, form the
building blocks of the flexible
manufacturing system (FMS).
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Numerical Control (NC)


Numerical control (NC) is a form of
flexible (programmable) automation in
which the process is controlled by
numbers, letters, and symbols.
The electronic industries association
(EIA) defined NC as

“A system in which actions are controlled
by the direct insertion of numerical data
at some point. The system must
automatically interpret at least some
portion of this data.”
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Basic Components

An NC system consists of the machine tools,
the part-program, and the machine control
unit (MCU).
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Machine Tools


The machine tools perform the useful
work.
A machine tool consists of.
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
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
A worktable,
One or more spindles, motors and
controls,
Cutting tools,
Work fixtures, and.
Other auxiliary equipment needed in the
machining operation.
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
The drive units are either powered by
stepping motors (for open-loop
control), servomotors (for close-loop
control), pneumatic drives, or
hydraulic drives.
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The Part-program


The part-program is a collection of all data required
to produce the part. It is arranged in the form of
blocks of information.
Each block contains the numerical data required for
processing a segment of the work piece.
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The Machine Control Unit

The machine control unit consists of the data
processing unit (DPU) and the control loop
unit (CLU).
 The DPU decodes the information contained
in the part-program, process it, and
provides instructions to the CLU.
 The CLU operates the drives attached to the
machine leadscrews and feedback signals
on the actual position and velocity of each
one of the axes. The drive units are
actuated by voltage pulses.
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The Machine Control Unit

The number of pulses transmitted to each
axis is equal to the required incremental
motion, and the frequency of these pulses
represent the axial velocity.
 Each incremental motion is called a basic
length unit (BLU).
 One pulse is equivalent to 1 BLU.
 The BLU represents the resolution of the NC
machine tool.
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Types of NC Systems
Point-to-point (PTP) NC


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The cutting tool is moved relative to the
work piece (i.E., Either the cutting tool
moves, or the work piece moves) until the
cutting tool is at a numerically defined
position and then the motion is paused.
The cutting tool then performs an operation.
When the operation is completed, the cutting
tool moves relative to the work piece until
the next point is reached, and the cycle is
repeated.
The simplest example of a PTP NC machine
tool is the NC drilling machine.
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Straight-cut NC
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Straight-cut system are capable of
moving the cutting tool parallel to one
of the major axes (X-Y-Z) at a
controlled rate suitable for machining.
It is appropriate for performing milling
operations to fabricate work pieces of
rectangular configurations.
Straight-cut NC systems can also
perform PTP operations.
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Contouring NC
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
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In contouring (continuous path)
operations, the tool is cutting while
the axes of motion are moving.
The axes can be moved
simultaneously, at different velocity.
The path of the cutter is continuously
controlled to generate the desired
geometry of the work piece.
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Computer-assisted NC
Programming
1.
2.
3.
The computer interprets the instructions in
the program into computer-usable form.
The computer performs the necessary
geometry and trigonometry calculations
required to generate the part surface.
The part-programmer specifies the part
outline as the tool path. Since the tool path
is at the periphery of the cutter that
machining actually takes place, it must be
offset by the radius of the cutter.
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4.
5.
The cutter offset computations in
contour part-programming are
performed by the computer.
Part-programming languages are
general-purpose languages. Since
NC machine tool systems have
different features and capabilities,
the computer must take the general
instructions and make them specific
to a particular machine tool system.
This function is called post
processing.
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6.
7.
After converting all instructions into a
detailed set of machine tool motion
commands, the computer controls a
tape punch device to prepare the
tape for the specific NC machine.
Graphic proofing techniques provide
a visual representation of the cutting
tool path.
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8.
9.
This representation may be a simple
two-dimensional plot of the cutter
path or a dynamic display of tool
motion using computer generated
animation.
If necessary, part-programs are also
verified on the NC station using
substitute materials such as light
metals, plastics, foams, wood,
laminates, and other castable low
cost materials used for NC proofing.
Production Automation Technologies (Henry C. Co)
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Computer Numerical
Control (CNC)

The EIA definition of computer numerical
control (CNC).

“A numerical control system wherein a dedicated,
stored program computer is used to perform some
or all of the basic numerical control functions in
accordance with control programs stored in the
read-write memory of the computer.”
The CNC uses a
dedicated
microprocessor
to perform the
MCU functions.
Production Automation Technologies (Henry C. Co)
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
CNC supports programming features not
available in conventional NC systems:
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Subroutine macros which can be stored in
memory and called by the part-program to
execute frequently-used cutting sequence.
Inch-metric conversions, sophisticated
interpolation functions (such as cubic
interpolation) can be easily accomplished in CNC.
Absolute or incremental positioning (the
coordinate systems used in locating the tool
relative to the work piece) as well as PTP or
contouring mode can be selected.
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



The part-program can be edited (correction or
optimization of tool path, speeds, and feeds) at
the machine site during tape tryout.
Tool and fixture offsets can be computed and
stored.
Tool path can be verified using graphic display.
Diagnostics are available to assist maintenance
and repair.
Production Automation Technologies (Henry C. Co)
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Direct Numerical Control
(DNC)

The EIA definition of DNC.


“A system connecting a set of numerically controlled
machines to a common memory for part program or
machine program storage with provision for on-demand
distribution of data to machines.”
In DNC, several NC machines are directly controlled by a
computer, eliminating substantial hardware from the
individual controller of each machine tool. The partprogram is downloaded to the machines directly (thus
omitting the tape reader) from the computer memory.
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Industrial Robots

A programmable device equipped with a tool
that can move along several directions.
Stand-Alone
Operation: once a
program is entered,
the robot can function
with or without further
human intervention.
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The Manipulator
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
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The manipulator is the equivalent of the
machine tool in CNC. It consists of a series
of segments, jointed or sliding relative to
one another, that performs the work such as
grasping and/or moving objects.
The manipulator is composed of the main
frame (the arm of the robot), and the wrist.
The tools, called the end-effectors, are
attached to the wrist. The end-effectors
perform a prescribed task ordinarily done by
the human worker.
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The Main Frame

Structurally, the robot can be classified
according to the coordinate system of the
main frame. The types of coordinate
systems are:
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Cartesian coordinate manipulator, which consists
of three linear axes,
Cylindrical coordinate manipulator, which consists
of two linear axes and one rotary axis,
Spherical coordinate manipulator which consists of
one linear and two rotary axes,
Articulated or jointed robots which consists of
three rotary axes, and
Gantry robot
SCARA robot.
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Cartesian Robot
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Cylindrical Robot
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Spherical Robot
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Articulated (Jointed) Robot
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Gantry Robot
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SCARA Robot
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The Wrist
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The end-effectors is connected to the main
frame of the robot through the wrist.
The wrist has three rotary axes -- roll, bend
(pitch), and swivel (yaw).
The end-effectors. Attached to the wrist is
the end-effectors. The end-effectors is the
robot's “hand.” The most common endeffectors is the gripper, which is a device by
which a robot may grasp and hold external
objects.
Other standard end-effectors include welding
torch, magnetic vacuum, gun mounts for
spray painting or coating operations,
hydraulic toggle, and custom made tools.
Production Automation Technologies (Henry C. Co)
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Resolution,Accuracy,Repeatability
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Resolution is the smallest increment of
distance that can be read and acted upon by
an automatic control system of a robot.
The unit of measure is the basic resolution
unit (BRU).
The accuracy of an industrial robot is the
ability of the robot to make a motion with an
end point as specified by a program.
The closeness of agreement of repeated
position movement under the same
conditions to the same location is called the
repeatability of the robot.
Production Automation Technologies (Henry C. Co)
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Programming

An industrial robot can be
programmed using the
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

Manual teaching method,
Lead-through method, or a
Programming language.
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Applications

Perhaps the most extensive
applications of industrial robots are in
jobs involving repetitive tasks.
Industrial robots installed to-date are
in
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Material handling (about 40%),
Painting and arc welding (45%),
Inspection, assembly and
Other operations (15%).
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Operations that require precise
positioning control.
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
For example, in spray painting where
severe articulation is required.
Use of industrial robots in sand blasting is
on the rise not only because of the
abrasive environment, but the severe
articulation requirements of the process.
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In areas where hazardous working
conditions exist and/or where heavy
parts are involved.
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
For example, in unloading of die casting
machines, the workplace is dirty and hot
(molten metal); in spot welding
operations, the welding guns are heavy
and the work cycles rigorous; and in
investment casting, the environment is
abrasive and of the loads heavy.
Industrial robots are also replacing the
human operator in corrosive environment,
such as handling of dangerous chemicals.
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Hazards, operator tasks, inspection, quality,
part presentation, part weight, product
variation, product runs, frequency of
changeover, process variables, process
equipment, floor space, and cycle time, are
some of the variable that must be examined
in justifying the use of industrial robots.
However, industrial robots should not be
treated simply as an emulation of human
work. More importantly, the justification
process should reflect an accurate
implementation of corporate manufacturing
plans for competitive advantage and
productivity improvement.
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