Computer Aided Engineering Applications 3. Advanced...

Computer Aided Engineering

Applications

3. Advanced Manufacturing 3.5 NC programming

3.6 Automated Manufacturing systems

Engi 6928 - Fall 2014

3.6 Automated Manufacturing systems

3.7 Rapid prototyping

3.5 Part programming3.5 Part programming

Structure of an Automated manufacturing system

Product

descriptionCAM software MCU

Machine

Hardware

Data IO

SCADA


HardwarePDE NC

CODEControl

Commands


• A Part program is a sequence of instructions which

describe the manufacturing operations to be

performed on a work piece, in the form required by a

computer controlled manufacturing machine.

• Upon receiving of the part program (NC code), the

automated machine executes the instructions in the automated machine executes the instructions in the

code line by line.

A typical NC Code

•The main program

•N specifies the sequence number

•Comments can be given in brackets or

after;


Some of the main NC codes

• Setup commands

– G90/91 Absolute programming/ Incremental programming

– G70/G71 Inch / Metric format

– G54..G59 Work Coordinate system (set by probe)

– G28 Return to Home

• Linear interpolation vs Rapid traverse• Linear interpolation vs Rapid traverse

– G00 X5 Y6 Rapid traverse to point (5,6) (typically 5-20 m/min speeds)

– G01 X5 Y6 Linear interpolation to point (5, 6). (@ feed rate)


• Miscellaneous commands

– M03/M04/ M05 spindle on CW/CCW/ off

– M07/M08/ M09 coolant on mist/flood/ off

– M02 program end

– M06 tool change

• Spindle, Feed and tools• Spindle, Feed and tools

– S 1000 set spindle 1000 rpm

– F 1 set feed rate 1 mm/min

– T01 select tool 01


• Circular interpolation

– G02 X5 Y5 R5

(move to x5 y5 with radius 5

clockwise)

• Cutter compensation

– G 40/41/42 Cutter radius compensation

Cancel/ Left/ Right

– G 43/49 Cutter height compensation/ cancel


• Job setup – Work offset

G54 Setup

• Job setup – Tool offset

– tool diameter/ height compensation

– Tool wear


Tool offset setup


Exercise 1– Write part programs for the following tool

paths.

Thickness =20mm

Tool Info

Tool # 1

Drill ∅5

S=1200

F=70

Tool #2

Drill the 4 holes and perform the finishing profile cut

Dimensions are Metric

Tool #2

End Mill ∅20

S=2000

F=400

Assume G54 set at

the top face

Tool Table

T1 L15 D5

T2 L15 D20


• Path verification using NC corrector-

– Limitations (tool setup), work offset setup

– Cutter length offset

3.6 Automated Manufacturing systems3.6 Automated Manufacturing systems

Structure of an Automated manufacturing system

Product


Machine

Hardware

Data IO

SCADA


HardwarePDE NC

CODEControl

Commands


Main components


Mechanical Components


Mechanical Components

Belt Drives


Axis configurations

Z

X

2 Axis CNC Lathe

3 Axis CNC Mill5 Axis CNC Mill Configurations


Stepper motor drives

•Open loop

•Low load applications

•Initialization with Limit switches

•Step sequences are used to control the motors

•Basic Length Unit (BLU) = Pitch of ball screw

Steps per revolution

Example: 400 half steps per rev, 4mm

Pitch implies a 10 um BLU


Servo motor drives Relays

•Closed loop PID using quadrature encoders

•More precise than stepper drives

•Initialization with Limit switches/ absolute encoders

•Direction step commands given to PID as reference

•Basic Length Unit (BLU) = Pitch of ball screw

Resolution of encoder

ON/OFF relay drivers


Machine Control unit

NC CODE•Read G code Line by Line

•Interpolate points from current

to target

•Generate Individual axis

To A

ctua

tor d

rivers

•Generate Individual axis

reference commands (inverse

kinematics)

To A

ctua

tor d

rivers


Summary

Machine Control Unit

Decode NC code

Interpolation

Axis command

NC Code

file

Servo DrivesPower

Module

Stepper Drives

USB/LAN

24V

5VQuadrature decoders

Axis command

generation

file

Relay DrivesUSER I/O

Job setup

Manual controls

Code Edits

RS232


Exercise: Identify the axis reference commands and the motor

voltage commands for the following lines of GCode. Assume a

24 V relay and stepper with 400 half steps per revolution

connected to a 4mm lead ball screw.

Exercise: Identify the main system components involved in

designing a 3 axis PCB drilling machine.

G01 X0.05 F100

G01 X0.03 F50

M07

designing a 3 axis PCB drilling machine.

ҩ

3.7 Rapid prototyping3.7 Rapid prototyping

• Rapid prototyping is a group of techniques used to

quickly fabricate a scale model of a physical part or

assembly using three-dimensional computer aided

design (CAD) data.

There are many methods used in RP. The methods • There are many methods used in RP. The methods

are also referred to as additive manufacturing


1. SLA – Stereo Lithography apparatus

Materials : Resins

Ά


2. SLS – Selective laser sintering

Materials : Metallic powders

Polymer powders


3. FDM- Fused deposition modelling

Materials : ABS – (M30)

MUN: Fortus 400mc

ᡰҧ


4. Zcorp printers

Multi-Jet modelling

Polyjet modelling

Investment casting

Computer Aided Engineering Applications 3. Advanced...

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