09-10 cutting operations

8/7/2019 09-10 Cutting Operations

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Cutting OperationsCutting Operations

Ref 3Ref 3

Chapter 3Chapter 3


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Learning ObjectivesLearning Objectives

Producing blanksProducing blanks

Cutting holesCutting holes

Progressive workingProgressive workingSize control operationsSize control operations


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IntroductionIntroduction

CuttingCutting operationsoperations areare

classified either by theclassified either by the

purpose or the shape ofpurpose or the shape of

the cutting action:the cutting action:-- Operations for producingOperations for producingblanksblanks

ShearingShearing

CutoffCutoff

PartingParting

BlankingBlanking

Operations for cutting holesOperations for cutting holes

PunchingPunching

SlottingSlotting

PerforatingPerforating

Operations forOperations for

progressive workingprogressive working

NotchingNotching

SemiSemi--notchingnotching LancingLancing

PartingParting

CutoffCutoff

Operations for SizeOperations for Size

ControlControl TrimmingTrimming

SlittingSlitting

ShavingShaving

When a piece or sheet metal is cut fromWhen a piece or sheet metal is cut fromstrip or coil and that piece becomes the partstrip or coil and that piece becomes the partor product being manufactured, the piece isor product being manufactured, the piece is

referred to as the blank or work piecereferred to as the blank or work piece


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ShearingShearingTo be classified as shearing,To be classified as shearing,the cutting actionthe cutting action must be alongmust be alonga straight linea straight line

Performed on shearingPerformed on shearingmachinesmachines

May be foot, hand or powerMay be foot, hand or poweroperatedoperated

Cutting action occursCutting action occursprogressively along the bladeprogressively along the blade

Used to cutUsed to cut

Blanks for automotive panelsBlanks for automotive panels Narrow stripsNarrow strips

To square edgesTo square edges

To be classified as cutoff,To be classified as cutoff,

cutting action maycutting action may be along abe along a

line, angle or curveline, angle or curve

May involve one or more cutsMay involve one or more cuts

CutoffCutoff


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ShearingShearing


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Shearing CharacteristicsShearing Characteristics

The shearing process characteristics include:The shearing process characteristics include:

Its ability to make straightIts ability to make straight--line cuts on flat sheetline cuts on flat sheetstockstock

Metal placement between an upper and lower shearMetal placement between an upper and lower shearbladesblades

Its trademark production of burred and slightlyIts trademark production of burred and slightlydeformed metal edgesdeformed metal edges

Its ability to cut relatively small lengths of material atIts ability to cut relatively small lengths of material at

any time since the shearing blades can be mountedany time since the shearing blades can be mountedat an angle to reduce the necessary shearing forceat an angle to reduce the necessary shearing forcerequired.required.


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PartingParting

Parting is anParting is an

operation in which tooperation in which to

single line cuts aresingle line cuts are

made to cut blanksmade to cut blanksfrom the stripfrom the strip

Blanks do not nestBlanks do not nest

perfectlyperfectly

Results in scrapResults in scrap

To be classified as blanking,To be classified as blanking,

the cutting action must bethe cutting action must be

about a complete or enclosedabout a complete or enclosed

contourcontour

Results in excessive wasteResults in excessive wasteMost inefficient operation forMost inefficient operation for

cutting blanks from sheetcutting blanks from sheet

metalmetal

The waste left after blanking isThe waste left after blanking is

in the form of a ribbonin the form of a ribboncommonly known ascommonly known as skeletonskeleton

BlankingBlanking


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BlankingBlanking


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Characteristics of BlankingCharacteristics of Blanking

Its ability to produce economical metal work piecesIts ability to produce economical metal work pieces

in both strip and sheet metal during medium orin both strip and sheet metal during medium or

high production processes,high production processes,

The removal of the work piece from the primaryThe removal of the work piece from the primary

metal stock as a punch enters a die,metal stock as a punch enters a die,

The production of a burnished and sheared sectionThe production of a burnished and sheared section

on the cut edge,on the cut edge,

TheThe productionproduction of burred edges,of burred edges,

The control of the quality by the punch and dieThe control of the quality by the punch and die

clearance,clearance,

The ability to produce holes of varying shapesThe ability to produce holes of varying shapes

quickly.quickly.


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Down Side Effects of BlankingDown Side Effects of Blanking

The blanking process has some downside effects. TheseThe blanking process has some downside effects. Theseinclude:include:

Generating residual cracks along the blanked edges,Generating residual cracks along the blanked edges,

Hardening along the edge of the blanked part or workHardening along the edge of the blanked part or workpiece, andpiece, and

Creating excess rollCreating excess roll--over and burr if the clearance isover and burr if the clearance isexcessive.excessive.

The most common materials used for blanking includeThe most common materials used for blanking include

aluminum, brass, bronze, mild steel, and stainlessaluminum, brass, bronze, mild steel, and stainlesssteel. Due to its softness, aluminum is an excellentsteel. Due to its softness, aluminum is an excellent

material to be used in the blanking process.material to be used in the blanking process.


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PunchingPunching

When holes are cut in blankWhen holes are cut in blank

Involves the cutting of cleanInvolves the cutting of cleanhole with resulting scrap slughole with resulting scrap slug

PiercingPiercingproduces hole byproduces hole by

tearing action so is nottearing action so is notpunchingpunching

Some people prefer to call theSome people prefer to call thecutting of elongated andcutting of elongated andrectangular holes by termrectangular holes by termslottingslotting

When many holes areWhen many holes arepunched in pattern techniquepunched in pattern techniqueis calledis called perforatingperforating

Notching is an operationNotching is an operationfor removing a piece offor removing a piece ofscrap metal from thescrap metal from theedge of the stripedge of the strip

When notch like cutoutsWhen notch like cutoutsare made in centralare made in central portionportionof the progressive stripof the progressive stripthe operation used isthe operation used issemisemi--notchingnotching

NotchingNotching


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Punching HolesPunching Holes


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NotchingNotching


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Characteristics of NotchingCharacteristics of Notching

Characteristics of the notching process include:Characteristics of the notching process include:

Only removes metal from the outside of a workOnly removes metal from the outside of a work

piecepiece

Is capable of making different angle notchesIs capable of making different angle notches

(accomplished by adjusting the location of the(accomplished by adjusting the location of the

work piece)work piece)

Produces cuts not possible when using theProduces cuts not possible when using theshearing processshearing process

Can be used as a process to facilitate later rollCan be used as a process to facilitate later roll

forming or stamping processesforming or stamping processes


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LancingLancing

When a cut is madeWhen a cut is made

partway through thepartway through the

metal, and no scrapmetal, and no scrap

metal is freed frommetal is freed fromthe strip, thethe strip, the

operation is calledoperation is called

lancinglancing

Frequently combinedFrequently combined

with bendingwith bending

The cutting off of theThe cutting off of the

excess or damagedexcess or damaged

metal after a drawingmetal after a drawing

operation is calledoperation is calledtrimmingtrimming

TrimmingTrimming


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ShavingShaving

Involves cutting offInvolves cutting off

metal in a chipmetal in a chip

fashionfashion

The clearance usedThe clearance usedbetween cuttingbetween cutting

edges is close to zeroedges is close to zero

The cutting up of aThe cutting up of a

wide coil into severalwide coil into several

coils for usability iscoils for usability is

called slittingcalled slittingPair of circular knivesPair of circular knives

or blades are usedor blades are used

SlittingSlitting


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SlittingSlitting

The slitting processThe slitting process

characteristics include:characteristics include:

being restricted to cuttingbeing restricted to cutting

relatively thin materials (0.001relatively thin materials (0.001

to 0.125 in.),to 0.125 in.),leaving leftleaving left--over burrs on slitover burrs on slit

edges of the narrower coals,edges of the narrower coals,

its ability to be used on bothits ability to be used on both

ferrous and nonferrous metals,ferrous and nonferrous metals,

its categorization as a highits categorization as a highproduction designed to controlproduction designed to control

metal coil widthmetal coil width


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SummarySummary

Cutting operationsCutting operations

ShearingShearing

CutoffCutoff

PartingParting

BlankingBlanking

Operations for cutting holesOperations for cutting holes

PunchingPunching

SlottingSlotting

PerforatingPerforating

NotchingNotching

LancingLancing

TrimmingTrimming

ShavingShaving

SlittingSlitting


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QuestionsQuestions

09-10 cutting operations

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