Cams Ys Overview

8/22/2019 Cams Ys Overview

1/54

CAM Systems & CNC Machine

Overview - Lecture 3

Overview to Computer Aided Manufacturing -

ENGR-2963 - Fall 2005

Class Manager - Sam Chiappone


2/54

Intro to CAM

ChiapponeRensselaer Polytechnic Institute

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(repeatability). MIT is the subcontractor and

builds the machine for the project.


3/54

Intro to CAM


History: Continued

1959 - MIT announces Automatic Programmed

Tools (APT) programming language

1960 - Direct Numerical Control (DNC). This

eliminates paper tape punch programs and allowsprogrammers to send files directly to machine

tools


4/54

Intro to CAM


History: Continued

1968 - Kearney & Trecker machine tool builders

market first machining center

1970s - CNC machine tools & Distributed

Numerical Control

1980s - Graphics based CAM systems

introduced. Unix and PC based systems available


5/54

Intro to CAM


History: Continued

1990s - Price drop in CNC technology

1997 - PC- Windows/NT based Open Modular

Architecture Control (OMAC) systems

introduced to replace firmware controllers.


6/54

Intro to CAM


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 ofthe motor001 is possible


7/54

Intro to CAM


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


8/54

Intro to CAM


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


9/54

Intro to CAM


Control Systems

Closed-Loop Advantages

DC motors have the ability to reverse instantly to adjust

for position error

Error compensation allows for greater positionalaccuracy (.0001)

DC motors have higher torque ranges vs.. stepper

motors

Closed-loop limitations Cost


10/54

Intro to CAM


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 axiss controlledsimultaneously


11/54

Intro to CAM


Three Basic Categories of

Motion Systems


12/54

Intro to CAM


CNC vs. 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 atthe machine tool.


13/54

Intro to CAM


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


14/54

Intro to CAM


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 arereferred to as hardwire controls and were popular

from the 1950s to 1970s.


15/54

Intro to CAM


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


16/54

Intro to CAM


Machining Centers

Machine motion is programmable

Servo motors drive feed mechanisms for tool axiss

Positioning feedback is provided by resolvers to the

control system


17/54

Intro to CAM


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 havemultiple spindles.


18/54

Intro to CAM


Machining Centers


19/54

Intro to CAM


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.


20/54

Intro to CAM


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 allprogramming in the defense and aerospace industries


21/54

Intro to CAM



Requires excellent 3D visualization skills

Capable of generating machine code for complicated

part programs 5 axis machine tools


22/54

Intro to CAM



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


23/54

Intro to CAM


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


24/54

Intro to CAM



Tool & material libraries

Tool path simulation

Tool path editing

Tool path optimization

Cut time calculations for cost estimating


25/54

Intro to CAM



Import / export capabilities to other systems Examples:

Drawing Exchange Format (DXF)

Initial Graphics Exchange Standard (IGES)


26/54

Intro to CAM


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 or Blueprint

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


27/54

Intro to CAM



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)


28/54

Intro to CAM



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)


29/54

Intro to CAM



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)


30/54

Intro to CAM



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, rpms, etc.

G & M function capabilities


31/54

Intro to CAM


Output: NC Code

Numerical Control (NC) Language

A series of commands which direct the cutter motion

and support systems of the machine tool.


32/54

Intro to CAM


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


33/54

Intro to CAM


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


34/54

Intro to CAM


Example of CNC

Programming What What Must Be Done To Drill A Hole On A

CNC Vertical Milling Machine


35/54

Intro to CAM


TopView

FrontView

Tool Home

1.) X & Y Rapid To Hole Position


36/54

Intro to CAM


TopView

FrontView

2.) Z Axis Rapid Move

Just Above Hole

3.) Turn On Coolant

4.) Turn On Spindle

.100


37/54

Intro to CAM


TopView

FrontView

5.) Z Axis Feed Move toDrill Hole


38/54

Intro to CAM


TopView

FrontView

6.) Rapid Z Axis Move

Out Of Hole


39/54

Intro to CAM


TopView

FrontView

9.) X&Y Axis Rapid

Move Home

7.) Turn Off Spindle

8.) Turn Off Coolant

Tool At HomeHeres The CNC Program!


40/54

Intro to CAM


TopView

FrontView

Tool At Home

O0001

N005 G54 G90 S600 M03

N010 G00 X1.0 Y1.0

N015 G43 H01 Z.1 M08N020 G01 Z-.75 F3.5

N030 G91 G28 X0 Y0 Z0N035 M30

N025 G00 Z.1 M09

Heres The CNC Program!

Tool At Home


41/54

Intro to CAM


TopView

FrontView

Tool At Home

O0001O0001

Number Assigned to this program

Tool At Home


42/54

Intro to CAM


TopView

FrontView

Tool At Home

O0001

N005 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


43/54

Intro to CAM


TopView

FrontView

O0001

N005 G54 G90 S600 M03

N010 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


44/54

Intro to CAM


TopView

FrontView

O0001

N005 G54 G90 S600 M03

N010 G00 X1.0 Y1.0

N015 G43 H01 Z.1 M08

G43 Tool Length Compensation

H01 Specifies Tool length compensation

Z.1 Z Coordinate .1 in. from Zero

M08 Flood Coolant On


45/54

Intro to CAM


TopView

FrontView

O0001

N005 G54 G90 S600 M03

N010 G00 X1.0 Y1.0

N015 G43 H01 Z.1 M08N020 G01 Z-.75 F3.5

G01 Straight Line Cutting Motion

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

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


46/54

Intro to CAM


TopView

FrontView

O0001

N005 G54 G90 S600 M03

N010 G00 X1.0 Y1.0

N015 G43 H01 Z.1 M08N020 G01 Z-.75 F3.5

G00 Rapid MotionZ.1 Z Coordinate .1 in. from Zero

M09 Coolant Off

N025 G00 Z.1 M09


47/54

Intro to CAM


TopView

FrontView

O0001

N005 G54 G90 S600 M03N010 G00 X1.0 Y1.0

N015 G43 H01 Z.1 M08

N020 G01 Z-.75 F3.5

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


48/54

Intro to CAM


TopView

Front

View

O0001

N005 G54 G90 S600 M03

N010 G00 X1.0 Y1.0

N015 G43 H01 Z.1 M08

N020 G01 Z-.75 F3.5

N035 M30

N030 G91 G28 X0 Y0 Z0

N025 G00 Z.1 M09

M30 End of Program

O t t NC C d C d


49/54

Intro to CAM


Output: NC Code - Canned

Cycles


50/54

Intro to CAM


CAD to NC CodeGeometry

Direct input

Tool Path GenerationWhat you want to cutHow you want to cutTool TypeRpms FeedsMethodCanned cyclesCut direction

Post Process

DXF

IGES

Import

File

CL

File

NC CodeN1 G80 G90

N3 G0 T01 M06N5 G0 X0 Y0

OEMCustom

Language

Advantages of CNC Machine


51/54

Intro to CAM



Tools

Ease of part duplication

Flexibility

Repeatability

Quality control through process control



52/54

Intro to CAM



Tools

Accommodates simple to complex parts geometry

Improved part aesthetics

Increased productivity

Technology costs are decreasing



53/54

Intro to CAM



Tools

Reduced set-up time

Reduced lead times

Reduced inventory

Better machine utilization

Job advancement opportunities



54/54

Intro to CAM



Tools

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 Rpms and feeds

Cams Ys Overview

Documents

Transcript of Cams Ys Overview