Technology II. Ing. Jan Tomíčekutopm.fsid.cvut.cz/podklady/TE2/Lectures/Lecture_no... · Milling 2D; 2,5D ... EdgeCAM, SurfCAM, SolidCAM, MasterCAM, OneCNC, ESPRIT, GibbsCAM. Simulaton

Technology II.

Ing. Jan Tomíček

CNC machines

Tool is moving in

coordinate system.

Tool position is then

defined by

coordinates.

When moving in

space we recognize

coordinates X,Y,Z or

X,Z

Shape generation

With CNC control we can program

complex toolpath

Simple tool – complex path (compare with

mass production)

Video – comparation of

tools

Turning

Turning

2 axes – X,Z

3 axes – X,Z,C + powered tools

4 axes – X,Z,Y,C + powered tools

QUICK TURN NEXUS 100-II

QUICK TURN NEXUS 400-II-MY

Controlled axes

Drilling

2D

Milling

2D; 2,5D

3D

4D – rotary milling

5D – multiaxis milling

Multiaxis machines

5 axis necessary

Aditional are for

Second turret

Sub-spindle

Pallete changer etc.

Programming of machines

Machining on CNC machines is controled by a NC code.

NC code is a list of instructions for themachine and also for the operator. Instructionare executed in time order.

NC code must have a specific format so thatthe control system of machine is able to readit.

NC code example

NC code form

Structure and form of NC code is

standardized by international standard -

ISO 6983 – Numeric control programs

formating

Differences between different control

system manufacturers and differences

between versions.

NC code structure

Lines (blocks)

Words

Word has a meaning and value part

S 1500

ISO nc code and the others

ISO is standardized code (G – code)

Some manufacturers devoloped their own

standard for NC code – native standard

Mazak – Mazatrol

Heidenhein – iTNC

Siemens - Sinumeric

NC code structure II.

Heading lines

Definition of relation between coordinatesystem of CNC machine and program, type of programing, work mode, workingconditions

Program body

Cutting and non-cuting moves, main program and subprograms, tool changes

Ending lines

Tool return to home point, change to first tool, coordinates reconstruction

Coordinate systems

Ways how to define a movement

a) Absolute programing – position is in all

point expressed as a distance from

zero-point

b) Incremental programing – position is

expressed as a change from last

postion

Absolut

G90 X0 Y0 Z50

G0 X20 Y70 Z50

G1 X20 Y70 Z0

G1 X40 Y70 Z0

G0 X40 Y70 Z50

G0 X0 Y0 Z50

Incremental

G91

G0 X20 Y70 Z0

G1 X0 Y0 Z-50

G1 X20 Y0 Z0

G1 X0 Y0 Z50

G1 X-40 Y-70 Z0

1.

2.

3.

2.

3.

1.

Ways of programing

Manual programing

Shopfloor programming

Automated programing

Manual programing Editors are used. Program is written

manually (by hand) line after line.

Used for simple parts (but complex too)

Toolpath is exactly

defined

Program can be adjusted

to save time

Can use canned cyles

Can be parametrized

Used in mass production

Manual programingWe need to know the functions: (many more function exist)

Movement functions:

G00 rapid movement

G01 linear interpolation/movement

G02/03 circular interpolation

G40 diameter compensation off

G41 diameter compensation on /right handed

G42 diameter compensation on /left handed

Support and help functions:

M06 tool change

M03/04 spindle start CW/CCW

M05 program stop

M30 program end

Manual programming

Specilzed editors

Predator G-code editor

G Wizard

Mikronex

show

Shopfloor programing Somewhere in between manual and automated

Uses cycles with parameters

We have to edit these

parameters manually

But the NC code

is generated

automatically

No postprocessing

Shopfloor programming

Control system use – programming on

machine

- No costs (together with machine)

- Fast use (macros)

- Time waste (program x work)

- Comfort (on machine x in office with PC)

- Shape limitations

Heidenhein

show

Automated programming

Work with the „sequential NC code

preparation“

Uses CAM (Computer Aided

Manufacturing) software

For all parts including complex shapes

We dont need to compute the toolpath

We need correct postprocessor

Sequential NC code preparation

Partprogram – workpiece, material, cutting conditions, tools…

Procesor – according to technology

CL data – virtual toolpaths on virtual machine

Postprocesor – „translator“ forthe specific CAM-controlsystém-machinecombination

NC code – toolpaths of a realtool on a real machine

Partprogram

Procesor

Postprocesor

CL-data

NC-kód

CAM software

is Computer Aided Manufacturing (machining)

From simple 2-axis turning up to multiaxismachining

Feature or technologically oriented

Special types of CAM for special purpose

Live presentation

xD software

2D – just in two axis - turning

2,5D – two axis, but in layers – not

simultaneously

3D – three axes simultaneously

multiaxis

4D – four axis - one rotary axis (rotary

table)

5D – five axis - maching (two rotary axes)

4Axis

xD software

2D – just in two axis - turning

2,5D – two axis, but in layers – not

simultaneously

3D – three axes simultaneously

multiaxis

4D – four axis - one rotary axis (rotary

table)

5D – five axis - maching (two rotary axes)

5D milling

http://youtu.be/Fjzhygzafr0

Sequential NC code preparation

Partprogram – workpiece, material, cutting conditions, tools…

Procesor – according to technology

CL data – virtual toolpaths on virtual machine

Postprocesor – „translator“ forthe specific CAM-controlsystém-machine combination

NC code – toolpaths of a realtool on a real machine

Partprogram

Procesor

Postprocesor

CL-data

NC-code

Partprogram

Consist from:

- Geometrical part –

- model(s) for machining, blank(s), jigs and

fixtures, tools and machines and other

geometrical parts

- Coordinate system and its position

- Start points, reference points, safety

clearance plane, transfer planes.

31

Partprogram

Consist from:

- Technological part –

- Tool properties

- Operation steps

- Machining strategy

- Cutting and technological conditions

- Approach and retract moves, trasfer movesof the tool

- Usage of special machine parts

32

Tool movement programming

CAM software uses „Strategies“

Strategy – is a general plan how to movethe tool durign machining

Continual development

Roughing – offset, raster (Zig-Zag method) plunging

Finishing strategies – pencil milling, streaming, rest material maching

Strategies types

3 basic groups:

1) Raster

2) Offset

3) Control curve

Raster

Raster = pattern

existing known pattern,

projected on plane of

machining

Offset

Offset = equidistant

Curve derived from the

border of machined area

- constant MRR

- keeps the machining direction

- prevents low cut depths/slices

- BUT – increases number of lifts

and submerging

Control curve strategy

Control curve = geometry

that sets the tool path

Derived from existing

geometry

User defined

- No respect to model, can undercut

- can be smoother that model following

- Special object = more data, more work

- Calculation tollerance problem

CAM software developers

NX (Siemens PLM software) Catia

(Dassault systémes) – both 10%

market share

PowerMill, FeatureCAM, ArtCAM

(Delcam company) ,InventorCAM

(Autodesk) Wildfire – Pro/Ingineer

(PTC) – 5%

EdgeCAM, SurfCAM, SolidCAM,

MasterCAM, OneCNC, ESPRIT,

GibbsCAM

Simulaton and verification

Simulation is used to

control generated

toolpaths for following

reasons:

- Colisions

- Undercuts (or rest

material)

- Postprocesing

check

Verification

NX show

Automated programing - review

We can do complex shapes, no need to calculate control points

We can use simulation and verification

We can change the tool easily

But

We need postprocessor

Expensive

Program is always longer (againexpensive)