Seco - Turning

Seco Seco Core curriculum of metalcutting -- page page 11

1/56COPYRIGHT © 2008, Seco Tools AB

TurningTurning


Turning Turning toolholderstoolholders



Right-handedtoolholder

Neutraltoolholder

Left-handedtoolholder

Toolholder hand, left or right?Toolholder hand, left or right?

Turning Turning toolholderstoolholders


ANSIANSI norm for norm for externalexternal toolholderstoolholders

Page 8

Hol di ng met hodHol di ng met hod

Insert sha peInsert sha pe

Tool hol der styleTool hol der style

Insert cl ea ra nce a ngl eInsert cl ea ra nce a ngl e

Ha nd of toolHa nd of tool Pocket styl ePocket styl e

Sha nk si zeSha nk si ze

ICIC( # 1/8”)( # 1/8”)

Qua lified l engthQua lified l ength

Ma nu fa ctu rersMa nu fa ctu rers

opti onopti on



ANSIANSI norm for norm for internalinternal toolholderstoolholders

Ba r ma teria lBa r ma teria l

Sha nk dia meterSha nk dia meter

B ori ng ba r lengthB ori ng ba r length


ICIC( # 1/8”)( # 1/8”)

Insert sha peInsert sha peTool hol der styleTool hol der style


Ha nd of toolHa nd of tool

Page 9


ISO norm for ISO norm for external toolholdersexternal toolholders



Tool hol der styleTool hol der style


Ha nd of toolHa nd of tool Sha nk hei ghtSha nk hei ght

Sha nk w idthSha nk w idth

Tool l enghtTool l enght

Cu tti ng edge Cu tti ng edge lengt hlengt h


opti onopti on



ISO norm for ISO norm for internal toolholdersinternal toolholders

Ba r ma teria lBa r ma teria l

Sha nk dia meterSha nk dia meter

B ori ng ba r lengthB ori ng ba r length


Insert sha peInsert sha pe Tool hol der styleTool hol der style


Ha nd of toolHa nd of tool

Cu tti ng edge Cu tti ng edge lengt hlengt h


opti onopti on


Negativeangle

Positiveangle

0°

Negative rake

Positive rake

Neutral rake

Rake Rake geometriesgeometries



Negative rake, used for steel, steel alloys, stainless steels, cast iron.

Positive rake, used for gummy materialsand some high–temperature alloys.

Neutral rake, used for threading, grooving, profiling and form tools.

Use negative rake whenever possible

Rake Rake geometriesgeometries


The working cutting edge (entering) angle Κ influences the chip formation, chip removal direction and the size and direction of the cutting forces.

Major cutting edge and κ

Cutting Rake γ − positive gives lowcutting forces and negative gives better chip breakage.

Κ

Back Rake λ – negative gives a robust cutting edge and positive gives a weaker cutting edge.

The nose radius and geometry(minor cutting edge)influence the surface finish.

Toolholder geometryToolholder geometry



D type holderFirst choice for general externalturning.

For negative inserts with a central hole.

P type holderFor negative inserts with a central hole.

No clamp on the top, facilitates free chip flow

Toolholders


C type holderDesigned mainly for Seco PCBN inserts without hole.

S type holderFor external and internal turning with positive inserts.

Toolholders



Choose as large a shank as possible (depends on machine)

ShankShank SizeSize

External Tool Holder


(Typical example )

Toolholders



ff

Impact of (changing) entering angle.

Toolholders


PTJNR, PTTNR

Entering angle, 93°, 60°

Insert, TN..

Toolholders



PVJNR

Entering angle, 93°

Insert, VN..

Toolholders


In the case of a slender workpiece, for example,these aspects can solve a practical problem (vibrations).

Toolholder Toolholder -- cuttingcutting forcesforces



MMulti ulti DDirectional irectional TTurningurning


Advantages of MDTSmaller number of tools.

Shorter adjustment times.

Shorter insert change times.

Less extra time.

Disadvantages of MDTLonger effective cutting time due to lower cutting speed.

Evaluation of effective time versus extra time is important. Thisdepends on the batch size and complexity of the workpiece.

(share of longitudinal turning)

MMulti ulti DDirectional irectional TTurningurning



Mini Shaft


Mini Shaft

• ID Turning

• ID Grooving

• Back facing

• Chamfering

• Profiling

• Threading

Exchangeable Head Small Diameter Boring SystemExchangeable Head Small Diameter Boring System



InsertsInserts


ANSIANSI norms norms for insertsfor inserts


Si de cl ea ra nce Si de cl ea ra nce a ngl ea ngl e

Tol era ncesTol era nces

TypeType

IC si zeIC si ze

Thi cknessThi ckness

N ose ra diu sN ose ra diu s

Cu tti ng edge Cu tti ng edge conditi onconditi on

Chi pb rea kerChi pb rea ker



ISOISO norms norms for insertsfor inserts


Si de cl ea ra nce Si de cl ea ra nce a ngl ea ngl e

Tol era ncesTol era nces

TypeType

Cu tti ng E dge L engt hCu tti ng E dge L engt h

Thi cknessThi ckness

N ose ra diu sN ose ra diu s

Cu tti ng edge Cu tti ng edge conditi onconditi on

Chi pb rea kerChi pb rea ker


CuttingCutting

edgeedge

lengthlength

InscribedInscribed circlecircle

ThicknessThickness

NoseNose radiusradius

InsertsInserts



The insert shape and size determines the maximum cutting depth.

InsertsInserts


Choose as small a diameter as possible!

Choose as large a diameter as possible!

.... CONFLICT!

Length

Dia

F

Boring BarsBoring Bars



Steel Densimet Carbide

Less than 3 : OK OK OK

Less than 6 : Vibration Risk of vibration OK

Less than 9 : Vibration Vibration Risk of Vibration

Greater than 9 : Vibration cannot be avoided using normal tools

Length

Dia

LengthDiameter

Overhang ratio =



In order to minimize vibration problems, change direction and size of

cutting force by, for example;

Entering angle = 90°Smaller nose radius and/or sharper cutting edge.Smaller cutting depth and larger feed.Change cutting speed.

Tang

entia

l




Tang

entia

l

Deformation

Practical consequence



The difference between milling and turning

Varying cutting forces (stress).Varying cutting temperatures (tension in insert).

Turning gradesTurning grades



Toughness!Toughness!




Economic tool life Economic tool life –– 15mins in steel & 10mins in stainless steel15mins in steel & 10mins in stainless steel



Wear resistance

Toughness

NN

H

SS

P TP3000TP2000TP1000

TP2500

M TP2500 TM2000 TP40TM4000

K TK1000 TK2000

TK1000 TK2000

Turning grades Turning grades –– CVD coatedCVD coated


Wear resistance

Toughness

NN

H

SS

P

M

K

890 883

Turning grades Turning grades –– uncoateduncoated



Wear resistance

Toughness

NN

H

SS

P

M

K

CP200 CP250 CP500

CP200 CP250 CP500

CP500

Turning grades Turning grades –– PVD coatedPVD coated


Wear resistance

Toughness

NN

H

SS

P

M

K

CMP CM

CM

Turning grades Turning grades –– CermetCermet



Range of chipbreakers

1 2 3 4 5 6 7 8 9

FF

F

MF

M

MR

R

RR

MF4

RR9

R8R7WR6

MR7

R4W

R 5

RR6

MR3 MR4

M1M3W M5

MF2W

MF1 MF3

F1W

F2W

FF1

MF5


WNMG080408W-M3

High productivity - wiperSemi-finishing and finishingTurning with very small cutting depths

Good surface finish - wiperFeed x 2 = the same surface finishThe same feed = Ra / 2

High feed inserts



Copying with D- and T-style wiper insertsSince D- and T-style Wiper inserts not are designed within ISO-tolerances an adjustment in the tool offset must be made.

A deviation from the nominal nose radius shape, will always occur (D1, D2) when going towards a corner.

High feed inserts


Inch

0.24

0.2

0.16

0.12

0.08

0.04

0.008

0.003 0.006 0.009 0.012 0.015 0.018 0.021 0.024 0.027 0.03 Inch

Feed Rate

Dep

th o

f Cut

MF2

MF5

M5

MF3

MF4F1

MR7

Application areas for chipbreakers



Prevents damage to the workpiece, tool and operator.

Avoids production stoppage.

Avoids chip evacuation problems.



Less power required to break.

Less stress on cutting edges.

Smaller increases in cutting forces.

Easier to evacuate.

Higher power required to break.

Higher stress on cutting edge.

Possible deflection & vibration.

Preferred—Short spiral chips

Avoid—Very short, tight chips

Avoid—Long, stringy chips

Extremely difficult to evacuate.

Can recut and damage the workpiece or tooling.




Plastic deformation of workpiece material due to shearing. (chiplamellae or chip segments).

Most of the energy required for machining is used in the shearing surface.

ChipWorkpiece

Tool

Sheare surface

Chip formationChip formation


Long chip materials have a flow zone on the underside. The thickness of the flow zone is influenced by the workpiece material, the machining angle and the cutting speed.

Flowzone

Chip formationChip formation



May not be larger than 2/3 of the cutting edge

length and no smaller than the nose radius.

ap = depth of cut

Turning applications


ap = depth of cut

ap influences the:• Metal removal rate (productivity).• Power consumption.• Chip formation.

ap is limited by: • Cutting edge length.




Feed rate (inch/rev)

If the feed rate is too low, the materialwill be compressed and the contactpressure will lead to premature wear ofthe tool and a poor surface finish. f

f = feed rate (inch/rev)



f = feed rate (inch/rev)

f influences the:Metal removal rate.Power consumption.Chip formation. Surface finish.

f is limited by:Nose geometry.Chipbreaking geometry.

f




Vc must be adapted to the insert gradeand the material of the workpiece.

Vc

Vc = Cutting speed (inch/min)



Vc = cutting speed (ft/min)

Vc influences:Metal removal rate (productivity).Power consumption.Tool life.

Vc is limited by:Cutting temperature.

Vc




RPM (n) is equal to

Vc x 123.14 x Ø

where Vc is the cutting speed.

n



Example



Example


TurningTurning

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