cad/cam theory-4

8/10/2019 CAD/CAM theory-4

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CAM

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Machinin Centers

A machining center can be defined as a

Multiple operation and processes in a single set-

Typically has an automatic mechanism to change

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Machinin Centers

Machine motion is programmable

Servo motors drive feed mechanisms for toolaxiss

Positioning feedback is provided by resolvers to

the control system

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Machinin Centers

Example - A turning center capable of OD

turning, external treading, cross-hole drilling,engraving, and milling. All in machining is

accom lished in one set-u . Machine ma

have multiple spindles.

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Pro rammin Methods

Automatically Programmed Tools (APT)

A text based system in which a programmerdefines a series of lines, arcs, and points whichdefine the overall part geometry locations. These

features are then used to generate a cutterlocation (CL) file.

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Pro rammin Methods-APT

Requires excellent 3D visualization skills

Capable of generating machine code forcomplicated part programs

5 axis machine tools

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Pro rammin Methods-CAM

Computer Aided Machining (CAM) Systems

Graphic representation of the part PC based

Some built-in expertise S eed & feed data based on material and tool s ecifications

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Tool path simulation

Tool path editing Tool path optimization

Cut time calculations for cost estimating

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Import / export capabilities to other systems

Examples: raw ng xc ange orma

Initial Graphics Exchange Standard (IGES)

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-

Start with graphic representation of part

Direct in ut

Import from external system Exam le DXF / IGES

2D or 3D scan Model or Blue rint

(At this point you have a graphics file of your

eometr

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The Process CAD to NC File

Define cutter path by selecting geometry

Pockets

Hole patterns Surfaces

Volume to be removed

At this oint the s stem knows what ou wantto cut)

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Tool information ype, pm, ee

Cut method xamp e - oc e m z g-zag, sp ra , ns e-ou

Rough and finish parameters

the part)

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Execute cutter simulation

Visual representation of cutter motion

Modify / delete cutter sequences

(At this point the system has a generic cutter locatione o e cu pa s

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Post Processing

CL file to machine specific NC code

Filters CL information and formats it into NC

Work envelope

- , , , .

G & M function capabilities

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Out ut: NC Code

A series of commands which direct the cutter

tool.

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CAD to NC Code

GeometryDXFImport

Direct inputIGESFile

Tool Path GenerationWhat you want to cutHow you want to cut

Rpms FeedsMethod

Canned cycles

Post Process CLFile

N1 G80 G90N3 G0 T01 M06

N5 G0 X0 Y0

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Advanta es of CNC Machine Tools

Flexibility

Repeatability

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geometry

mprove par aes e cs Increased productivity

Technology costs are decreasing

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CNC machine tools are more ri id thanconventional machine tools Less horse ower vs. conventional cuttin but re uires

a ridged machine tool with no backlash Increased Rpms and feeds

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Usin Pro E

ea ures n v ua geome ry crea e one a a me.Features include datums, extrusions, holes, rounds,chamfers surface features cuts atterns swee s etc.You can have multiple features in a part.

PartsCollection of geometric features that define thegeome r c en y ca e e par . ar s are re erre o ascomponents in an assembly. You can have multiplecom onents in an assembl .

AssembliesCollection of components assembled

together to create the model. You can have multipleassem es an su assem es n a erarc ca or eraccording to their relationships with other assemblies andthe master assembl .

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Pro NC Flow Chart

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Introduction

NC Sequences

An NC se uence is an assembl or work iecefeature that represents a single tool path.

When too much material is removed from thepart, it is said to be gouged or overcut..

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Gou in

en oo muc ma er a s remove rom e par , s sa o egouged or overcut.

The converse of gouging a work-piece is undercutting--notremoving enough material.

Interference between the workpiece and components of the

toolholders and shanks is called a collision. Gouging, undercutting and collisions are costly and result in a lot

.

The word most often associated with machine downtime is

gouging. Gouging a workpiece or surface is one of the biggest problems

that machinists face today because the number of complexworkpieces is increasing these days.

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Desi n Mode

The Pro/ENGINEER

design model,represen ng efinished product, is

manufacturing.

.2. Surfaces to be milled

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Work iece

The workpiece

represents the raws oc a s go ng o emachined by the

operations

1. Holes removed - not part of casting

2. Dimensions increased to allow formaterial removal

3. Dimensions decreased to allow formaterial removal

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Introduction

FixturesFixtures are parts or assemblies that help orient

manufacturing operation.

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Coordinate S stems

machine and act as the origin (0, 0, 0) for CL data

Yw

Machine Coordinate System

Ym

XwZw

Workpiece Coordinate System

XmZm

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Retract Surface

The retract surface

defines the level tow c e oo sretracted after a cut.

machining needs, you

surface to be a plane,

c linder s here or a 1. Retract lanecustom-made surface. 2. Retract cylinder

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O erations

workcell and using a particular coordinate system for CL data output. Name Workcell to be used Coordinate system for CL data output Retract surface

.

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Workcells

A workcell is a workpiece (or assembly) feature

that specifies a machine tool using: Name

Number of axes

A set of parameters

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Tools Setu

Select Manufacturing Setup->Tooling

NC Manufacturing requires the followinggeneral categories of information abouttools:

Tool Type

Geometry parameters

oo um er

Offset Number

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Other Tools Parameters

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Built in Tools

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Built in Tools

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Built in Tools

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Built in Tools

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Built in Tools

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Built in Tools

50 East

West01st

Qtr

3rd

Qtr

North

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Milling Turning Using

ro

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Milling (3-Axis)

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Mill Geometr

n ow

by projecting the silhouette of the reference part on the Mill

Window start plane, by sketching or by selecting a closedcontour. All surfaces visible within the contour are milled

Mill Volumes Sketch the volume to be machined or excluded intersect the volume

with the workpiece or reference model, or offset surfaces (forexample, by tool radius). You can use this set of tools in anycombinations to define a single Mill Volume

Trim a Mill Volume Subtracts the reference model from the current volume definition and

only the remaining volume is used for machining.

Mill Surfaces

A Mill surface is a special surface feature, created by the set oftechni ues that can be used in Surface millin NC se uences.

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Mill Surfaces

,the set of techniques that can be used in Surface

milling NC sequences.

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Cut Parameters

TOLERANCE

1. TOLERANCE2. Design Surface3. Machined Surface

4. Tool Centerline path5. Tool

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F d


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Feed

_

CUT_UNITS nc es per m nu e e au , ee per m nu e ,

MMPM (millimeters per minute), FPR (feet per revolution),IPR (inches per revolution), MMPR (millimeters perrevolution).

RETRACT_FEED

_

FREE_FEED

PLUNGE_FEED

PLUNGE_UNITS

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D fi i T l


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Definin Tools

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It is a very versatile sequence used not

onl to rou h machine the work iece butcan also perform finishing and facing

A Volume milling NC sequence removes-

by-slice. All slices are parallel to the retract

p ane;

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P fil Milli


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Profile Millin :

Profile milling is used to roughor finish mill vertical or slantedsur aces. e sur acesselected must allow for a

.

depth of the cut is defined by

surfaces.

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S f Milli


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Surface Millin

ur ace m ng equence s genera yused to semi-finish or finish the shallow

.can generate a lot of toolpath strategies

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T t Milli


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Tra ector Millin

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CL D t G r ti


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CL Data Generation

Cutter Location (CL) data files are generated fromthe cutter paths specified within NC Manufacturing

sequences.

Each NC sequence generates a separate CL file.

You can also create a single file for a wholeoperation.

These CL data files can then be passed to machine-specific or generic post-processors for NC tapegenerat on or commun cat ons

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CL Data Continue


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CL Data Continue

$$* Pro/CLfile Version Wildfire 3.0 - M020 $$-> MFGNO / TRAINING $$-> FEATNO / 892 MACHIN / UNCX01, 1 $$-> CUTCOM_GEOMETRY_TYPE / OUTPUT_ON_CENTER UNITS / MM

LOADTL / 1-> . $$-> CSYS / 1.0000000000, 0.0000000000, 0.0000000000, 0.0000000000, $ 0.0000000000, 1.0000000000, 0.0000000000, 0.0000000000, $ 0.0000000000, 0.0000000000, 1.0000000000, 0.0000000000 SPINDL / RPM, 1000.000000, CLW RAPID GOTO / 5.0000000000, 40.0000000000, 5.0000000000 RAPID GOTO / 5.0000000000, 40.0000000000, -1.0000000000

FEDRAT / 10.000000, MMPM GOTO / 5.0000000000, 40.0000000000, -2.0000000000 CIRCLE / 10.0000000000, 40.0000000000, -2.0000000000, $ 0.0000000000, -0.0000000000, -1.0000000000, 5.0000000000 GOTO / 10.0000000000, 45.0000000000, -2.0000000000 GOTO / 90.0000000000, 45.0000000000, -2.0000000000 CIRCLE / 90.0000000000, 40.0000000000, -2.0000000000, $ -0.0000000000, -0.0000000000, -1.0000000000, 5.0000000000 GOTO / 95.0000000000, 40.0000000000, -2.0000000000 GOTO / 95.0000000000, 10.0000000000, -2.0000000000 . , . , - . , -0.0000000000, 0.0000000000, -1.0000000000, 5.0000000000 GOTO / 90.0000000000, 5.0000000000, -2.0000000000 GOTO / 10.0000000000, 5.0000000000, -2.0000000000 CIRCLE / 10.0000000000, 10.0000000000, -2.0000000000, $ -0.0000000000, -0.0000000000, -1.0000000000, 5.0000000000

-

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. , . , . GOTO / 5.0000000000, 40.0000000000, -2.0000000000 GOTO / 5.0000000000, 40.0000000000, 5.0000000000

SPINDL / OFF $$-> END / FINI

NC Post Processin


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NC Post-Processin

anu ac ur ng genera es cu er oca on(CL) data files in an ASCII format that need toe pos -processe o crea e ac ne on ro

Data (MCD) files before any machininge u .

Select which post-processor to use.

Execute post-processors with option to run CLfile.

Execute post-processors with options directlyu on out ut of tool ath.

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NC Post Processin Continue


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NC Post-Processin Continue

-

UNCX01 Mill G-Post

File to CNC PartProgram

Select CL Data->PostProcessor

Select the Post

Processor name to etCNC Part ProgramFile.

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CNC Part Pro ram of Tra ector millin


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CNC Part Pro ram of Tra ector millin

Sequence. (Date:10/22/08 Time:13:21:01) N0001G98G80G90G49G17 N0002G54 N0003T1M6 N0004S1000M3 N0005G0X5.Y40. N0006G43Z5.H1 N0007Z-1. N0008G1Z-2.F10. N0009G2X10.Y45.I5.J0. N0010G1X90. N0011G2X95.Y40.I0.J-5.

. N0013G2X90.Y5.I-5.J0. N0014G1X10. N0015G2X5.Y10.I0.J5.

N0016G1Y40. N0017Z5. N0018M5 N0019M30 %

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Transferrin CNC Part Pro ram to


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Transferrin CNC Part Pro ram to

CNC Machine

Serial port COM1 (or any free COM port)

Baud According to Machine e.g. 2400

Data bits 7

Parity Even

Stop bits 2

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Out ut: NC Code


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Out ut: NC Code

G-Codes (G00, G1, G02, G81)

Coordinate data (X,Y,Z) Feed Function (F)

Miscellaneous functions M13

N - Program sequence number-

S - Spindle command

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Turning

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Lathe Continue


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Lathe Continue

AreaDefine the area in the model cross sectionwhere you want the material to be removed.

ProfileInteractively define the cut motion(s) byeither sketching or using surfaces or datum curves.

GrooveTurn narrow grooves using a tool withcutting edges on both sides and a peck-type motion.

ThreadCut threads on a lathe.

HolemakingDrill, bore, and so on.

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Stock Boundar and Cut Extensions


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Stock Boundar and Cut Extensions

1. Reference part2. Workpiece

3. Stock boundary sketch4. Cut sketch5. Cut extensions6. Cut area

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Holder T e


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Holder T e_

1. Holder_Type Left

2.

Holder_Type Right

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Tool Definition


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Tool Definition

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Outside Area Turnin


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Outs de ea Tu

Define the Turn Profileby selecting surfaces of

e re erence parand specify the cut

the following illustration:

Positive Z (3).

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Inside Area Turnin


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To turn the inside surfaces of a cored workpiece, setthe TOOL_ORIENTATION parameter value to 0.Then define the Turn Profile (1) and cut extensions as

,extensions: Negative Z (2) and Positive Z (3).

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Groovin Continue


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