Dr. HABEEB HATTAB HABEEB Office: BN-Block, Level-3, Room-088 Email: hbuni61@yahoo

University TENAGA Nasional Lecturer: Dr. HABEEB ALANI

Dr. HABEEB HATTAB HABEEBDr. HABEEB HATTAB HABEEB

Office: BN-Block, Level-3, Office: BN-Block, Level-3, Room-088Room-088

Email: Email: [email protected]. No.: 7292Ext. No.: 7292

mailto:[email protected]

http://www.dewittindustries.com/cgibin/ibrowse/images/of_12/animations/mechanical/gear/gear


UUniversity TENAGA Nationalniversity TENAGA National

College Of EngineeringCollege Of EngineeringMechanical DepartmentMechanical Department

Lecture NoteLecture Note

University TENAGA Nasional Lecturer: Habeeb Al-Ani

CAMCAM

Computer Aided ManufacturingComputer Aided Manufacturing


Overview

• Computer Aided Manufacturing Defined• Brainstorming Exercise• CAM activities• How It Works• Summary• Conclusion


Computer Aided Manufacturing

• What is Computer Aided Manufacturing?

– It is “control of the manufacturing process by

computers” involving the integration of CAD

engineering data and the computerized

equipment which manufactures the product.



• Other definitions:– “Computer aided manufacturing concerns the use

of algorithms for planning and controlling fabrication processes.”

– Computer aided manufacturing is “the use of computers for managing manufacturing processes.”



• Using technology to produce• Leveraging capital investments• Increasing productivity through automation• Decreasing lead time through programming

and controlled machinery


Brainstorming Exercise

• How can CAM benefit your company?– Integrate design and manufacturing– Make mass customization possible– Reduce costs– Leverage computing power– Automate manufacturing processes



• Identify benefits and costs of CAM:– Direct Benefits– Indirect Benefits– Tangible Costs– Intangible Costs



• What processes in your company could be more efficient through CAM?


CAM activities

• Essentially the collection of computer technologies used in manufacturing– Computer Numerical Control (CNC)– Direct Numerical Control (DNC)– Flexible Manufacturing System (FMS)– Robots– Automated material Handling Systems


• Computer Numerically Controlled (CNC)– Machine that is controlled by computer– Utilizes monitor and keyboard for operator

interaction– Facilitates greater control over quality– Allows machine to monitor the maintenance of

its parts

CAM activities


• Direct Numerical Control (DNC)– Each machine contains own microprocessor– Entire bank of machines controlled by a single

central computer– If used with automated material handling,

considered to be a flexible manufacturing system

CAM activities


• Direct Numerical Control (DNC)

CAM activities

• Direct Numerical Control (DNC)

CAM activities

• Flexible Manufacturing System (FMS)– Numerous computer-controlled machines fed by

automated material handling system– Allows for broad and deep product mix– Minimal setup times enable small lot sizes

CAM activities


• Robots– Mechanical manipulators that can be accessed

with programming method– Consistent, repetitive-motion tolerant– Ideal for tasks that are hazardous to humans

CAM activities


• Automated Materials Handling System– System where raw materials are automatically

fed into machines– Examples:

• Conveyor belts• Automated Guided Vehicles (AGV)• Automated Storage and Retrieval Systems (ASRS)

CAM activities


How It Works

1. Product is conceived by engineer2. Product is designed using CAD software3. CAD data is transferred to manufacturing

machine’s memory4. Machine uses the CAD data to produce the

product, with little human intervention


How It Works

• Old System (without CAM)– Product is designed with CAD software

• Each production machine is programmed individually

OR – if not automated :• Employees are trained on proper production of the

product


How It Works

• New System (using CAM)– Product is designed with CAD software

• Product specifications are sent over the plant network to each machine

• Machines have ‘intelligence’ to produce the products without human intervention


– CAM solution:• Enables faster turnaround of new products• Reduces waste by using raw materials more

efficiently• Generates costs based on design specifications


Summary

• Here’s what we’ve looked at so far….– Definition– Brainstormed– CAM activities– How It Works– CAM solution


Conclusion

• CAM enables companies to leverage capital investment

• CAM allows for cost savings that can be passed on to the final consumer

• CAM utilizes human resources more efficiently to minimize labor costs


RememberRemember && rememberremember XX 1000 1000

If you want to be part of a profession dedicated to quality

and continuous improvement, consider CAM as your career of choice…



CAM Systems & CNC CAM Systems & CNC MachineMachine


History

• 1955 - John Parsons and US Air Force define a need to develop a machine tool capable of machining complex and close tolerance aircraft parts with the same quality time after time. MIT is the subcontractor and builds the machine for the project.


History: Continued

• 1959 - MIT announces Automatic Programmed Tools (APT) programming language

• 1960 - Direct Numerical Control (DNC). This eliminates paper tape punch programs and allows programmers to send files directly to machine tools


History: Continued

• 1968 - Kearney & Trecker machine tool builders market first machining center

• 1970’s - CNC machine tools & Distributed Numerical Control

• 1980’s - Graphics based CAM systems introduced. Unix and PC based systems available


History: Continued

• 1990’s - Price drop in CNC technology• 1997 - PC- Windows/NT based “Open

Modular Architecture Control (OMAC)” systems introduced to replace “firmware” controllers.


Control Systems

• Open-Loop Control– Stepper motor system– Current pulses sent from control unit to motor– Each pulse results in a finite amount of revolution

of the motor001” is possible

Control Systems

• Open-Loop Limitations– Control unit “assumes” desired position is

achieved– No positioning compensation– Typically, a lower torque motor

• Open-Loop Advantages– Less complex, Less costly, and lower maintenance

costs


Control Systems

• Closed-Loop Control– Variable DC motors - Servos– Positioning sensors -Resolvers

• Feedback to control unit • Position information compared to target location• Location errors corrected

Control Systems

• Closed-Loop Advantages– DC motors have the ability to reverse

instantly to adjust for position error– Error compensation allows for greater

positional accuracy (.0001”)– DC motors have higher torque ranges..

stepper motors


Control Systems

• Closed-loop limitations– Cost


Three Basic Categories of Motion Systems

• Point to Point - No contouring capability • Straight cut control - one axis motion at a

time is controlled for machining• Contouring - multiple axis’s controlled

simultaneously


Three Basic Categories of Motion Systems


CNC - NC Machine Tools

• Computer Numerical Control (CNC) - A numerical

control system in which the data handling, control

sequences, and response to input is determined by

an on-board computer system at the machine tool.


CNC

• Advantages– Increased Program storage capability at the machine tool

– Program editing at the machine tool

– Control systems upgrades possible

– Option -resident CAM system at machine tool

– Tool path verification


Machining Centers

– Machine motion is programmable

– Servo motors drive feed mechanisms for tool

axis’s

– Positioning feedback is provided by resolvers to

the control system


NC

• Numerical Control (NC) - A control system which primarily processes numeric input. Limited programming capability at the machine tool. Limited logic beyond direct input. These types of systems are referred to as “hardwire controls” and were popular from the 1950’s to 1970’s.


Machining Centers

• A machining center can be defined as a machine tool capable of:– Multiple operation and processes in a

single set-up utilizing multiple axis– Typically has an automatic mechanism to

change tools


Machining Centers

• Example - A turning center capable of OD turning, external treading, cross-hole drilling, engraving, and milling. All in machining is accomplished in one “set-up.” Machine may have multiple spindles.


Programming Methods-APT

– Developed as a joint effort between the aerospace industry, MIT, and the US Airforce

– Still used today and accounts for about 5 -10% of all programming in the defense and aerospace industries


Machining Centers


Programming Methods

• Automatically Programmed Tools (APT)– A text based system in which a programmer

defines a series of lines, arcs, and points which define the overall part geometry locations. These features are then used to generate a cutter location (CL) file.



– Requires excellent 3D visualization skills

– Capable of generating machine code for complicated part programs

• 5 axis machine tools



• Part definition– P1=Point/12,20,0– C1=Circle/Center,P1,Radius,3– LN1=Line/C1. ATANGL,90

• Cutter Commands– TLRT,GORT/LN1.TANTO,C1– GOFWD/C1,TANTO,L5


Programming Methods-CAM

• Computer Aided Machining (CAM) Systems– Graphic representation of the part– PC based– Integrated CAD/CAM functionality– “Some” built-in expertise

– Speed & feed data based on material and tool specifications



– Tool & material libraries– Tool path simulation– Tool path editing– Tool path optimization – Cut time calculations for cost estimating



– Import / export capabilities to other systems• Examples:

– Drawing Exchange Format (DXF)– Initial Graphics Exchange Standard (IGES)


The Process CAD to NC File

• Start with graphic representation of part– Direct input– Import from external system

• Example DXF / IGES

– 2D or 3D scan• Model

(At this point you have a graphics file of your geometry)



• Define cutter path by selecting geometry– Contours– Pockets– Hole patterns– Surfaces– Volume to be removed

(At this point the system knows what you want to cut)



• Define cut parameters– Tool information

• Type, Rpm, Feed

– Cut method• Example - Pocket mill zig-zag, spiral, inside-out• Rough and finish parameters

(At this point the system knows how you want to cut the part)



• Execute cutter simulation– Visual representation of cutter motion

• Modify / delete cutter sequences

(At this point the system has a “generic” cutter location (CL) file of the cut paths)



• Post Processing– CL file to machine specific NC code

• Filters CL information and formats it into NC code based on machine specific parameters– Work envelope– Limits - feed rates, tool changer, rpm’s, etc. – G & M function capabilities


Output: NC Code

• Numerical Control (NC) Language– A series of commands which “direct” the cutter

motion and support systems of the machine tool.


Output: NC Code

• G-Codes (G00, G1, G02, G81)

• Coordinate data (X,Y,Z)

• Feed Function (F)

• Miscellaneous functions (M13)

• N - Program sequence number

• T - Tool call

• S - Spindle command


Output: NC Code

• NC Program Example – N01G90 G80– N03 GOO T12 M06– N05 GOO X0 Y0 Z.1 F10 S2500 M13– N07 G1Z-.5– N09 G02 X-10. I0J0F20– N13 X0Y10– N17 X10Y0– N19 X0Y-10– N21 X-10Y0– N23 M2


Example of CNC Programming

• What What Must Be Done To Drill A Hole On A CNC Vertical Milling Machine


Top View

Front View

Tool Home

1.) X & Y Rapid To Hole Position


Top View

Front View

2.) Z Axis Rapid Move

Just Above Hole

3.) Turn On Coolant

4.) Turn On Spindle

.100”


Top View

Front View

5.) Z Axis Feed Move to

Drill Hole


Top View

Front View

6.) Rapid Z Axis Move

Out Of Hole


Top View

Front View

9.) X&Y Axis Rapid

Move Home

7.) Turn Off Spindle

8.) Turn Off Coolant


Top View

Front View

Tool At Home

O0001N005 G54 G90 S600 M03N010 G00 X1.0 Y1.0N015 G43 H01 Z.1 M08N020 G01 Z-.75 F3.5

N030 G91 G28 X0 Y0 Z0N035 M30

N025 G00 Z.1 M09

Here’s The CNC Program!


Top View

Front View

Tool At Home

O0001O0001

Number Assigned to this program


Top View

Front View

Tool At Home

O0001N005 G54 G90 S600 M03N005 Sequence Number

G54 Fixture Offset

G90 Absolute Programming Mode

S600 Spindle Speed set to 600 RPM

M03 Spindle on in a Clockwise Direction


Top View

Front View

O0001N005 G54 G90 S600 M03N010 G00 X1.0 Y1.0

G00 Rapid Motion

X1.0 X Coordinate 1.0 in. from Zero

Y1.0 Y Coordinate 1.0 in. from Zero


Top View

Front View

O0001N005 G54 G90 S600 M03N010 G00 X1.0 Y1.0N015 G43 H01 Z.1 M08G43 Tool Length Compensation

H01 Specifies Tool length compensation

Z.1 Z Coordinate .1 in. from Zero

M08 Flood Coolant On


Top View

Front View


G01 Straight Line Cutting Motion

Z-.75 Z Coordinate -.75 in. from Zero

F3.5 Feed Rate set to 3.5 in./min.


Top View

Front View


G00 Rapid Motion

Z.1 Z Coordinate .1 in. from Zero

M09 Coolant Off

N025 G00 Z.1 M09


Top View

Front View


N030 G91 G28 X0 Y0 Z0G91 Incremental Programming Mode

G28 Zero Return Command

X0, Y0, Z0

X,Y,& Z Coordinates at Zero

N025 G00 Z.1 M09


Top View

Front View


N035 M30N030 G91 G28 X0 Y0 Z0N025 G00 Z.1 M09

M30 End of Program


Output: NC Code - Canned Cycles


CAD to NC Code

Geometry Direct input

Tool Path Generation What you want to cut How you want to cut

Tool Type Rpm’s – Feeds Method

Canned cycles Cut direction

Post Process

DXFIGES

ImportFile

CLFile

NC CodeN1 G80 G90N3 G0 T01 M06N5 G0 X0 Y0

OEMCustom

Language


Advantages of CNC Machine Tools

• Ease of part duplication• Flexibility• Repeatability• Quality control through process control



• Accommodates simple to complex parts geometry

• Improved part aesthetics• Increased productivity• Technology costs are decreasing



• Reduced set-up time• Reduced lead times• Reduced inventory• Better machine utilization• Job advancement opportunities



• CNC machine tools are more rigid than conventional machine tools– $$$- Climb milling requires about 10 - 15 % less horsepower

vs. conventional cutting, but requires a ridged machine tool with no backlash

– Increased Rpm’s and feeds



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