introduction to numerical control.ppt

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12/09/15 IE 447 - CIM Lecture Notes - Chapter 3

Numerical Control

1

IE 447IE 447

COMPUTER INTEGRATEDCOMPUTER INTEGRATED

MANUFACTURINGMANUFACTURING

CHAPTER 3CHAPTER 3

NUMERICAL CONTROLNUMERICAL CONTROL



12/09/15 2IE 447 - CIM Lecture Notes

-

'!t Is Nu#er$c!% Co&tro%'!t Is Nu#er$c!% Co&tro%((

An automated manufacturing process in whicha machine tool is controlled;

–

In an ordered sequence – Along a predetermined path – To require dimensions

–

At a specific feed and speed rate – Done through a group of alphanumeric

instructions




-

A )e*$&$t$o&+ A )e*$&$t$o&+

Numerical Control is a system in which

actions are controlled by the direct insertion

of numerical data at some point. Thesystem must automatically interpret at least

some portion of the data




-

MACHINE UNIT

NUMERICAL

CONTROLLER

NUMERICAL

DATA

(NC CODE)

MANUFACTURING

OPERATOR

PROCESSEDPART

Drive Control




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O,ect$.esO,ect$.es

1. Increased production

2. Reduced labor costs

. !a"e production more economical

#. !a"e production $obs easier

%. Do production $obs that are impossiblewithout numeric control

&. Increased accuracy on duplicate parts



12/09/15 IE 447 - CIM Lecture Notes

-

Tye! o" N#$eri%&l ControlTye! o" N#$eri%&l Control

Co&.e&t$o&!% Nu#er$c!% Co&tro% NCCo&.e&t$o&!% Nu#er$c!% Co&tro% NC

)$rect Nu#er$c!% Co&tro% )NC)$rect Nu#er$c!% Co&tro% )NC

Co#"uter Nu#er$c!% Co&tro% )NCCo#"uter Nu#er$c!% Co&tro% )NC




-

Co&.e&t$o&!%Co&.e&t$o&!% Nu#er$c!%Nu#er$c!%

Co&tro% NCCo&tro% NCData is sent to the machine tool by means of

punch cards or tapes. The reader at the

machine performs no calculations orinterpolations.



12/09/15 IE 447 - CIM Lecture Notes

-

)$rect Nu#er$c Co&tro% )NC)$rect Nu#er$c Co&tro% )NC

Is a method where a single computer

controls many numerical control

machine tools. These machine tools mayor may not be of a similar nature




-

Co#"uter Nu#er$c!% Co&tro%Co#"uter Nu#er$c!% Co&tro%

CNCCNCThe idea of computer numerical control is

to position a computer right at the

machine tool. !ost' if not all machine toolsthat are numericaly controlled are ()(

machine tools.




-

!s$c E%e#e&ts o* ! CNC ste#!s$c E%e#e&ts o* ! CNC ste#

COMPUTER

MACHINE

TOOL

MACHINE

CONTROL UNIT




-

Co#"uter Nu#er$c!% Co&tro% CNCCo#"uter Nu#er$c!% Co&tro% CNC




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A6.!&t!es A6.!&t!es

o Reduces time for

deli*ery of part

Reduces scrap rate ofmaterial

o Reduces tooling costs

o Reduces layout time

o Increases machine

and tool life

o Reduces storage

problems

o +ess setup timeo Reduces actual

machining time

Allows rapid design

changes in part +ess

$igs and fi,tures are

needed




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L$#$t!t$o&sL$#$t!t$o&s

o High initial investment

!achine tools cost -' / -1'%'

o High maintenance requirements !aintenance personnel must ha*e both

mechanical and electronics e,pertise

o Not cost-effective for low-level production on

simple parts

As geometric comple,ity or *olume increases()( becomes more economical




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I&6ustr$es Most A**ecte6 ,I&6ustr$es Most A**ecte6 ,

Nu#er$c!% Co&tro%Nu#er$c!% Co&tro%o Aerospace

o !achinery

o 0lectricalo abrication

o Automoti*e

o Instrumentationo !old ma"ing




-

N#$eri%&lly Controlle' M&%ine Tool!N#$eri%&lly Controlle' M&%ine Tool!

Functionally the same as a conventionalmachine tool. The diference is in the way inwhich the various machine functions andslide movements are controlled.The unctions and motions such as;

turning the spindle on and o setting cutting speeds setting feed rate turning coolant on and o moving tool with respect to work part

are perormed by Machine Control Unit(MCU) in NC machine tools.




-

)$str$,ut$.e Nu#er$c!% Co&tro%)$str$,ut$.e Nu#er$c!% Co&tro%

ecause ()( machine tools ha*e the ability torun multiple programs without being attached to

a centrali3ed computer this enables a centralized

computer to perform many different tas"s.

– +ine balancing

– 4cheduling

– !onitoring

– 5uality




CA)/CAMCA)/CAMThe idea behind (AD (A! is the use of a

single technical database by a both design a

manufacturing personnel during the product

de*elopment and production stages. – (AD systems are used to define part

geometries

– (A! systems are used to create cutter paths that can be used by the machine tool.

introduction to numerical control.ppt

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