session 08 computer aided manufacturing.pdf

7/27/2019 Session 08 Computer Aided Manufacturing.pdf

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Session Speaker

Mr. Umesh S.

1 M S Ramaiah School of Advanced Studies


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Session Ob ectivesOn completion of this Session, the delegates would have

understood about The aspects of Manufacturing Process Management

Computer Aided Manufacturing

Computer Aided Production Engineering

Com uter Aided Production Plannin

Computer Aided Quality Assurance

Numerical Control Machines

Programming for Numerical Control Machines



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ManufacturinManufacturing is the use of machines,

too s an a or to ma e t ngs or use or sale. The term may refer to a range of

human activity, from handicraft to high

tech but is most commonl a lied to

industrial production, in which raw

goods on a large scale.


http://en.wikipedia.org/wiki/Manufacturing


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Manufacturin Process Mana ementTools required for proper execution of various aspects of mfg. process

Computer Aided Manufacturing (CAM)

Production Engineering (CAPE)CNC, DNC, Robot OLP, Tooling/Fixtures

Production Planning (CAPP)

Mfg. concepts, Layout, Line balancing,

,

Quality Assurance (CAQ)Process and Ergonomic simulation, Resources

, , , - Costing (ABC)

Communication (ERP, MOM, HMI, PDM, SCADA )


Documentation


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Process PlanninTo establish which process and parameters are

to be used, as well as the machines performing

these processes, in order to manufacture the

component as per the design specification

Raw Material Finished ProductProcess

Planning

Raw material to be used

Sequence of machining/assembly operations

Processes and machines to be used for these operations

Tools, cutting speeds and feeds to be used for this purpose


eve op me o o ogy or qua y assurance


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Process PlanningShape and Size of the raw material (stock size)Identify datum

Identify and Group part featuresIdentify machining operations based on features and accuracy

Order/sequence of operation ( production/resource planning)

Select tools for each operation

Select/Design fixtures for each setup

machining parameters etc.)



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Com uter Aided Process Plannin

-

process plans

-

Stage III - Variant CAPP

-

Stage V - Dynamic, generative CAPP



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Com uter Aided Process Plannin Variant Approach:

Advance Manual Approach Utilise historical data stored in computers

Database of process plans for family of parts

Identify the family to which the part belongs e r eve process p an or a am y

Edit this plan as necessary to suit the requirement

or par o a new am y, eve op process p anmanually



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Com uter Aided Process Plannin Generative Approach: Process lan enerated from En ineerin

Specifications (graphical and textual) Read specification directly from CAD

Identify design features

Accept information about material, tolerances etc.roug npu

Accept information about raw material stock

process plans

Need ood database and lo ic or s stem to make a decision


Dynamic, generative CAPP


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Com uter Aided Process Plannin Process planning effort 58% Direct labor 10%

Improved cost estimatingprocedures and fewercalculation errors

Scrap 10% Tooling 12%

More complete and detailedprocess plans

or - n-process

Reduced process planning and

Improved production

scheduling and capacity

response to engineeringchanges Improved ability to introduce

new manufacturing technology

Greater process planconsistency; access to up-to-date information in a central

an rap y up ate processplans to utilize the improvedtechnology


http://www.npd-solutions.com/capp.html


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Com uter Aided Production Plannin Manufacturing concept planning

Factor la out lannin and anal sis

work flow simulation. walk-path assembly planning

lant desi n o timization

Mixed model line balancing

Workloads on multiple stations Process simulation tools e.g. die press lines, manufacturing

lines

Er onomic simulation and assessment of roduction assembl

tasks

Resource planning


http://en.wikipedia.org/wiki/Manufacturing_process_management


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Com uter Aided ualit Failure Mode and Effects Analysis

htt ://www.n d-solutions.com/fmea.html

Statistical process control -

Tolerance stack-up analysis


. .

/QAProducts/images/xbar.jpgp: www.me .n s .gov ga ery

ph/cmt/pages/herbb.htmhttp://www.3dcs.com/


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Co-ordinate Measurin Machine



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omputer e anu actur ng



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Machine ToolA powered machine for cutting or shaping or finishing

http://wordnetweb.princeton.edu/perl/webwn?s=machine%20tool

The main function of a machine tool is to remove metal

from a piece of work to give it the required shape and size

between the work-piece (job) and the tool

Machining equipment that cuts, shears, punches, presses, drills, rolls,grinds, sands, or forms metal, plastic, or wood stock. Not included in

-


, , .http://www-group.slac.stanford.edu/esh/hazardous_activities/machine_guarding/p_definitions.htm


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Conventional Machine Tool Fixing of the job (raw material)

Motion of the tool Manual control of the tool movement

Operator skill dependent productivity and quality

Low s eeds and feeds

Product complexity

Machine flexibility



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Com uter Aided ManufacturinTo automate the actual

Production process with least

Software used to generate the

instruction codes for a CNC

Information for machining:

amount of human intervention machine in order for it to cut out

a shape designed in a CAD

Shape to be machined

Accuracy to be achieved Automation

Sequence of machining

Spindle speed ccuracy Direction of rotationFeed Rate


Coolant flow


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Numerical Control NC MachineWeaving MachinesSelf playing pianos

Copying machines (not Xerox)

1940 John Parson (punched cards for drilling of multiple holes)

arson orp. on ro ys em eve opmen , servo a

1952 3-axis Cincinnati Hydrotel Milling machine (NC)

NC is a system in which actions are controlled by direct insertion

of numerical data (Part Program) at some point. The system must


automatically interpret at least some portion of this data


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Numerical Control NC Machine Automation Op. intervention

Flexibility

Accuracy

Cost Utilisation Skill Pre-planning



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Numerical Control NC Machine

Motion Control

Rotary (Servo Motors AC (cost)/DC (speed Var.)/Fluid(speed))



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Electric Drives To drive the main spindle (Spindle drive)

o r ve t e sa es or carr age x s r ve

Large variation in cutting speed (10 m/min to 1000 m/min)

Infinitely variable speeds between the upper and the lower

--

Direct Drive

Drive through gear box or through cogged belts



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LM Guides and Ball Screws

http://news.thomasnet.com/images/large/548/548044.jpg http://www.acorn-ind.co.uk/images/ball-screws.jpg

High Efficiency

Reduce friction and

wear

Reversibility Wear and Life


Smoother movement

Rigidity (pre-loading)


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Numerical Control NC Machine Reading the Part Program Decodin and rocess the ro ram statements

Convert the decoded information into control signals Receive and transmit feedback signals

Machine Control Unit (MCU)

Data Processing Unit

(DPU)

Control Loop Unit

(CLU)

Input Stream ReaderDate Reading Circuit

Decodin Circuit

InterpolatorPosition Control Loop

Velocit /Acc. Control Loo


Auxiliary Function Control


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Numerical Control (NC) Programming

NCVacuum Tube/1st generation Solid State Technology

Punched Tape input, no storage, processing one command at a time

CNC

IC and Memory Technology, Part Program input stored, Exchange

information between different units, PC style Controller (RAM, ROM,

Comm ports, Display, HD, KB, Editors, Graphic input devices), Canned

Subroutines in ROM

Communiction and Networking Technology, Central computer

,

and distribution of instructional blocks to NC machines

Communiction and Networkin Technolo , Central com uter for

DisNC Retrieval of Part Programs and its distribution to networked CNCmachines


N-axis m/c Number of axes along which motion can be controlled simultaneously


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Numerical Control NC MachineAxis Position # of pulses

x s e oc y u se requency



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Numerical Control NC Machine



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Numerical Control NC Pro rammin

Po nt to Po nt Systems:

Positioning, Drilling/Tapping, Punching

Contouring Systems:

Milling, Turning, Flame cutting



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Controls for NC machines O en Loo Control Closed Loo Control

no monitoring of theactual displacement of

Slide position isregulated by the

e mac ne s e

No comparison of

actual and re uired

erence e ween e

actual and programmed

positionposition

Motor controlled solely

Actual position is

constantly monitored

y e program npu

comparison

Very high accuracy



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Feedback devices Position Feed Back Velocit Feed Back

continuousmeasurement of the

Normally Tacho-generator is used

pos on o e cu ng

tool edge relative to the

datum point rotary or linear

measuring transducers.



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Structural Re uirements Normal weight distribution

result in rapid acceleration and deceleration of the slidesand the machines are subjected to fluctuating and variableforces during the machining operations

The machine structure should not bend due to the heavy

All the parts of the machine structure should remain inrelative relationshi re ardless of the ma nitude and

direction of the stresses developed due to these forces Another source of inaccuracy in the CNC machines is the


thermal distortion of the machine structure


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Cause of Inaccurac in Machine tools

Dynamic

Loading

Static Loading


Thermal Sources


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Safet of O erator

,

cannot be overlooked To ensure safe workin conditions the CNC

machine tools are provided with

Perimeter Guards Pressure mats

Light barriers


PEMP AME501


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Machinin Centers The latest developments in the CNC machine tools

are the versatile machining center.

This is a single machine capable of doing a

number of operations such as drilling, reaming,

tapping, milling and boring.

types o too s are mounte on a rum c a n or

egg box type magazine, which are put into the

the control of Tool Selection Instruction

33 M S Ramaiah School of Advanced Studies 33

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Tool Turrets


PEMP AME501


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NC Pro ramminDefine Geometry of part and motion of tool with respect to the work piece

Preparatory Information: Units, Positioning method Coordinates (X,Y, Z, RX, RY, RZ)

Tool/Tools to be used

Spindle Speed

Spindle On/Off

Coolant On/Off

Tool Control

Miscellaneous


PEMP AME501


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NC Pro ramminReference System:

Right Handed Cartesian Coordinate System

ZYX

Z-X plane

YXZ

Y-Z plane


XZY

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NC Pro rammin

Z-Axis:Part Rotating Spindle Axis/Direction of RotationTool Rotatin Tool Axis/Awa from the work iece

X-Axis:Part Rotating Moves tool away from the part


Tool Rotating To Right when moving along Z-axis facing the m/c

PEMP AME501


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NC Pro rammin

(2,3)

-

(2,3)

- -,

(1,-1)

,

(2,2)

(-1,-3) (1,-4)

Absolute Positioning Relative Positioning


PEMP- AME501


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NC Pro ramminProgramming Syntax:ns ruc ons as a sequence o oc s con a n ng

commands to set machine parameters

A block is a line of words

Each block is composed of several Commands

an associatedNumber

N30 G01 Z-0.125 F5


N35 X3 Y2 F10

PEMP- AME501


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NC Pro ramminLetter Codes

Each instruction to the machine consistsof a letter followed b a number.

Each letter is associated with a specific

ype o ac on or p ece o n orma on

needed by the machine.

Letters used in Codes


N,G,X,Y,Z,A,B,C,I,J,K,F,S,T,R,M

PEMP- AME501


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NC Pro ramminLetter Action association: Sequence Number (N): Block identifier (index)

* repara ory comman : u er mo on pos on ng

Dimension words (X,Y,Z,..): Location and orientation of cutter (BLU)

Feed Command F : Cutter Feed Rate units

Speed Command (S): Spindle Speed (rpm)

Tool Select Command (T): Tool selection from turret/tool changer Misc. Command (M): Spindle On/Off, Coolant On/Off

Circle Center (I,J,K): Center of a Circle

Dwell Command (P): Dwell Time (With G code)

% Program Start Flag G&M Code


:XXXX Program IdentifierSample File

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NC Pro ramminBlock Formats: Fixed Sequential: Fixed block length, contains same no. of words

Block Address: Change Codes used to indicate changes in a block

Tab Sequential: Modified Fixed block length, TAB key

,

Word Address: Each word is preceded by a letter identifying

the word type, followed by a number specifyingcontent


PEMP- AME501


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Part Pro ramminManual Part Programming:

Generate machining information in blocks based on the plannedmachining process using a Part Program Manuscript

Tedious

Invo ves ar t met c an tr gonometr c ca cu at ons

Prone to mistakes


PEMP- AME501


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Part Pro ramminComputer Assisted Part Programming:Use hi h level ro rammin lan ua es to define art eometr

and tool motions

Identify part geometry, general cutter motions, feeds, speeds

an cutter parameters

Code part geometry, cutter motions, and machine instructions

Compile the source to produce machine independent list of

cutter movement and and auxiliar machine control information

(Cutter Location Data File)

Post-process CL Data File to generate machine control data


for a particular machine (customisation)

PEMP- AME501


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Part Pro ramminAutomatically Programmed Tool (APT):

-

Definition of Geometry relevant to machining=

L1 = LINE/X1,Y1,Z1,X2,Y2,Z2

L2 = LINE/P1,P2

P1 = POINT/CENTER,C1

Motion Statement (location)

FROM/ oint location_

TO/point_location

GODLTA/x, y,z

GO/{TO},Drive Surface,{TO}, Part Surface {TO}, Check Surface

PAST, TANTO, ON Additional APT Statements, , , , ,

MACHIN/DRILL,2COOLNT/{MIST/FLOOD/OFF}

FEDRAT, SPINDL, TOOLNO, TURRET


,

MACRO CALLS

PEMP- AME501


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Part Pro ramminOther Part Programming Languages: ADAPT: Adaptation of APT for PCs, modular structure

Single Axis Positioning & Simple Contouring

in 2D and 3D

AUTOSPOT: Popular for positioning tasks (drilling)

Combined with ADAPT

EXPAT: Adapted APT for use in Europe

Three versions P to P, turning, 3D contouring

COMPACT: Language used is English-like and similar to

machine shop terminology


PEMP- AME501


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Part Pro ramminPart Programming from CAD:Utilise the art eometr data alread in di ital form in CAD

Part Programming from CAD:

CAD/CAM

Better Accuracy

Faster Development

Less prone to Errors

Less chances of model discrepancy


PEMP- AME501


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Part Pro ramminApproach to Part Programming from CAD:

Edit/Add geometry to define boundary for tools

Define Tool Geometry (library)

Identify the desired sequence of machining operations andp an t e requ re too pat an cutt ng parameters

Calculate coordinates of the points on the path (keep it low)

Graphically verify the generated path and correct if necessary

Create Cutter Location data file


Post-process CL data file to create Machine Code data file

PEMP- AME501


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Part Pro ramminTool Path Generation Considerations: Rou h Cut Castin /Rou h Cut Block

, ,

u er oca on o n


oug ng

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Part Pro ramminTool Path Simulation and Verification:

oo

Models

superimposed on geometry

Material to be removed is removed

Cutter does not hit clamps or fixtures

utter oes not pass t roug t e oor, s es or r s

Cutter ath is efficient


PEMP- AME501


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MPM Resources Dassault Systems (Delmia/Deneb)

PTC

ecnoma x

Surfware (SURFCAM)

Delcam (Powermill)

Proplanner


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Session Summar

The as ects of Manufacturin Process Mana ement

were described and explained

Application of Computer based tools in managing

various aspects of MPM were described

Brief history and working of Numerical Controlmachines were describe

Methodology of programming for NC Machines was

demonstrated


session 08 computer aided manufacturing.pdf

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