n c machines
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Computer Aided Design and
ManufacturingBranch: Mech Engg Semester: 5
Topic : CAM
Raghunathan Rajesh
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CAD CAM: Introduction Computer-aided design (CAD) is the use of a wide range of
computer-based tools that assist engineers in their design
activities. It involves both software and special-purpose
hardware.
Computer Aided Manufacturing can be defined as the use
of computer systems to plan, manage and control theoperations of a manufacturing plant through either direct
or indirect computer interface with the plants production
resources. Things taken care of by cam:
Verification of the data
Panelization of the design to fit the raw material
Ability to edit
Ability to add manufacturing information 2
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CAD CAM: Introduction
Fig : Product cycle in a computerized manufacturing environment3
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Computer-Aided Design (CAD)
Use of computer systems to assist in
the creation, modification, analysis,
and optimization of a design
Typical tools:
Tolerance analysis
Mass property calculations
Finite-element modeling and
visualization
Defines the geometry of the design
CAD CAM: Introduction
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Use of computer systems to plan,
manage, and controlmanufacturing operations
Direct or indirect computer
interface with the plants
production resources
Numerical control of machinetools
Programming of robots
CAD CAM: Introduction
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Computer-Aided Engineering (CAE)
Use of computer systems toanalyze CAD geometry
Allows designer to simulateand study how the productwill behave, allowing foroptimization
Finite-element method (FEM)
Divides model intointerconnected elements
Solves continuous fieldproblems
CAD CAM: Introduction
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Components of CAD/CAM/CAE Systems Major component is hardwareand software allowing shapemanipulation
Hardware includes graphicdevices and their peripherals forinput and output operations
Software includes packages thatmanipulate or analyze shapesaccording to user interaction
CAD CAM: Introduction
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The vision of the digital factory. Bracht, U. and Masurat, T. The digital factory between
vision and reality. Computers Industry, 2005, 56, 325333
CAD CAM: Introduction
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Digital manufacturing links product development, production planning, and facility
planning. Woehlke, G. and Schiller, E. Digital planning validation in automotive industry.
Computers Industry, 2005, 56, 393405
CAD CAM: Introduction
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Process Planning Theprocess plan is documentation determining all
machining operations, order of the operations, all machine
equipment, conditions and requirements to producing apart.
RAW STOCK PART
Machinery operationstype of machine
type of cutting tooltype of fixture
cutting condition
time, cost
DESISION
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Process Planning methods
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Process Planning
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Process Planning
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Numerical control
Numerical control is a method of automatically operating a
manufacturing machine based on a code of letters,
numbers and special characters. The numerical data
required to produce a part is provided to a machine in theform of a program, calledpart program. The program is
translated into corresponding electrical signal for input to
motors that run the machine.
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Numerical control
15Link:video\4 - CNC machining
http://localhost/var/www/apps/conversion/tmp/scratch_7/video/4%20-%20CNC%20machining%20-%20Concept%20car%20CADCAM-%20CNC%205%20axis%20machining.mp4http://localhost/var/www/apps/conversion/tmp/scratch_7/video/4%20-%20CNC%20machining%20-%20Concept%20car%20CADCAM-%20CNC%205%20axis%20machining.mp4http://localhost/var/www/apps/conversion/tmp/scratch_7/video/4%20-%20CNC%20machining%20-%20Concept%20car%20CADCAM-%20CNC%205%20axis%20machining.mp4http://localhost/var/www/apps/conversion/tmp/scratch_7/video/4%20-%20CNC%20machining%20-%20Concept%20car%20CADCAM-%20CNC%205%20axis%20machining.mp4http://localhost/var/www/apps/conversion/tmp/scratch_7/video/4%20-%20CNC%20machining%20-%20Concept%20car%20CADCAM-%20CNC%205%20axis%20machining.mp4http://localhost/var/www/apps/conversion/tmp/scratch_7/video/4%20-%20CNC%20machining%20-%20Concept%20car%20CADCAM-%20CNC%205%20axis%20machining.mp4http://localhost/var/www/apps/conversion/tmp/scratch_7/video/4%20-%20CNC%20machining%20-%20Concept%20car%20CADCAM-%20CNC%205%20axis%20machining.mp4 -
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Numerical control
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Numerical control
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Numerical controlpart programming
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Numerical control simulation
19Link: video\3b- CNC simulation
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http://localhost/var/www/apps/conversion/tmp/scratch_7/video/3b-%20CNC%20simulation%20-%20CNC%20programming%20and%20simulation%20turning.mp4http://localhost/var/www/apps/conversion/tmp/scratch_7/video/3b-%20CNC%20simulation%20-%20CNC%20programming%20and%20simulation%20turning.mp4http://localhost/var/www/apps/conversion/tmp/scratch_7/video/3b-%20CNC%20simulation%20-%20CNC%20programming%20and%20simulation%20turning.mp4http://localhost/var/www/apps/conversion/tmp/scratch_7/video/3b-%20CNC%20simulation%20-%20CNC%20programming%20and%20simulation%20turning.mp4http://localhost/var/www/apps/conversion/tmp/scratch_7/video/3b-%20CNC%20simulation%20-%20CNC%20programming%20and%20simulation%20turning.mp4http://localhost/var/www/apps/conversion/tmp/scratch_7/video/3b-%20CNC%20simulation%20-%20CNC%20programming%20and%20simulation%20turning.mp4http://localhost/var/www/apps/conversion/tmp/scratch_7/video/3b-%20CNC%20simulation%20-%20CNC%20programming%20and%20simulation%20turning.mp4 -
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Numerical control simulation
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Numerical controlpart programming example
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Numerical control
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So far
A brief overview of CAM
Next
An overview of the CNC machines
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Numerical control
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An overview of the CNC machines
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CNC hi
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CNC machines - Motion Control
A CNC machine takes the commanded position from the
CNC program
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CNC hi
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CNC machines
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CNC system elements -
Part program,Program input device ,
Machine control unit,
Drive system,
Machine tool,
Feedback system
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CNC machines
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Machine Control Unit - The machine control unit (MCU) is the
heart of a CNC system. It is used to perform the following
functions:
Read coded instructions
Decode coded instructions
Implement interpolations (linear, circular, and helical) to
generate axis motion commands
Feed axis motion commands to the amplifier circuits for
driving the axis mechanisms
Receive the feedback signals of position and speed for each
drive axis Implement auxiliary control functions such as coolant or
spindle on/off, and tool change
CNC hi
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CNC machines: Components
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CNC hi
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CNC machines: Components
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Linear motion stepping motor & lead screw
Drive system
CNC machines
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CNC machines: Components
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Feed Back System -
Open Loop Control System
Closed Loop Control SystemCNC feedback Devices
Potentiometers are used for position measurement based
on voltage ratios.
Encoders is a device used to convert linear or rotational
position information into an electrical output signal.
Resolver is a rotary transformer that produces an outputsignal that is a function of the rotor position.
Tachometers is used for velocity feedback where electrical
output is proportional to rate of angular rotation.
CNC machines d d
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CNC machines - How Axis Motion Is Commanded Understanding Coordinate Systems
Absolute Versus Incremental Motion Assigning Program Zero
Other Points About Axis Motion
Assigning Program Zero
Other Points About Axis Motion
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CNC machines CNC
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CNC machinesCNC program
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The coded instructions are composed of letters,
numbers and symbols and are arranged in a format of
functional blocks as in the following example
N10 G01 X5.0 Y2.5 F15.0
| | | | |
| | | | Feed rate (15 in/min)
| | | Y-coordinate (2.5")
| | X-coordinate (5.0")
| Linear interpolation modeSequence Number
CNC machines S l
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CNC machines Sample programO0001 (Program number)
N005 G54 G90 S400 M03 (Select coordinate system, absolutemode, and turn spindle on CW at 400 RPM)
N10 G00 X1 Y1 (Rapid to XY location of first hole)
N015 G43 H01 Z.1 M08 (Instate tool length compensation, rapid in
Z to clearance position above surface todrill, turn on coolant)
N020 G01 Z-1.25 F3.5 (Feed into first hole at 3.5 inches perminute)
N025 G00 Z.1 (Rapid back out of hole)N030 X.2 (Rapid to second hole)
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CNC machines S l
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CNC machines Sample programN035 G01 Z-1.25 (Feed into second hole)
N040 G00 Z0.1 M09 (Rapid out of second hole, turn offcoolant)
N045 G91 G28 Z0 (Return to reference position in Z)
N050 M30 (End of program command)
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CNC machines Sample program
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O - Program number
N - Sequence number
G Preparatory function
X - X-axis designation
Y - Y-axis designation
Z - Z-axis designation
R - Radius designation
F - Feedrate designation
S - Spindle speed designation
H - Tool length offset designation
D - Tool radius offset designation
T - Tool Designation
M - Miscellaneous function
CNC machines Sample program
CNC machines Di ti Of M ti (A )
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CNC machines - Directions Of Motion (Axes)
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Fig Axis Designation
Fig (b ) Axis Designation for Vertical & Horizontal Machines
CNC machines Di ti Of M ti (A )
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CNC machines - Directions Of Motion (Axes)
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Fig Axis Designation for turning machines
CNC machines Di ti Of M ti (A )
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CNC machines - Directions Of Motion (Axes)
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Fig Axis Designation for milling machines
CNC machines Reference point
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CNC machinesReference point
CNC machines Reference point
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CNC machinesReference point
CNC machines
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CNC machines
Accessories To The Machine - Examples of CNC
accessories include probing systems, tool length
measuring devices, post process gaging systems,
automatic pallet changers, adaptive control
systems, bar feeders for turning centers, live tooling
and C axis for turning centers, and automationsystems.
Programmable functions - The programmer must
also know what functions of the CNC machine are
programmable (as well as the related commands).
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CNC machine: motion and compensation
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CNC machine: motion and compensation
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Fig (a ) Tool Compensation for Milling (b ) Tool Compensation for Turning
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So far
A brief overview of CNC machines
Next
An overview of the CNC programming
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CNC machines
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An overview of the CNC programming
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CNC programming
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CNC programming
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CNC Programming Methods
Manual Programming
Conversational (Shopfloor) Programming
CAM System Programming
CNC programming
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CNC programming
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Procedure for manual NC programming
The procedure for manual programming can be divided into
four steps:
analysis of workshop drawings definition of work plans
choice of clamping devices and necessary tools (set-up
sheet)
generating the NC program (program sheet)
CNC programming
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CNC programming
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Informaton needed by a CNC
Preparatory Information: units, incremental or absolute positioning Coordinates: X, Y, Z, RX, RY, RZ
Machining Parameters: Feed rate and spindle speed
Coolant Control: On/Off, Flood, Mist
Tool Control: Tool and tool parameters
Cycle Functions: Type of action required
Miscellaneous Control: Spindle on/off, direction of rotation, stops
for part movement.
This information is conveyed to the machine through a set of
instructions arranged in a desired sequence Program.
CNC programming - Program Structure
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CNC programming Program Structure
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CNC programming - Program Structure
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CNC programming Program Structure
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Fig (b) Program Structure ( Block )
CNC programming - Program Structure
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CNC programming Program Structure
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Fig (c) Program Structure ( Word )
CNC programming - Program Structure
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Fig (d) Sequence of words in an NC Block
CNC programming Program Structure
CNC programming
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CNC programming