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


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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


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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


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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


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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


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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


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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

CNC hi


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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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Linear motion stepping motor & lead screw

Drive system

CNC machines


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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



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Fig Axis Designation for turning machines



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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

CNC machines


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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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Fig (b) Program Structure ( Block )



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Fig (c) Program Structure ( Word )



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Fig (d) Sequence of words in an NC Block


CNC programming


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CNC programming

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n c machines