Chip formation in the machining of hardened steel

Chip Formation in the Machining of Hardened Steel M.. The root cause o f high frequency, saw toothed chip formation i s found to be periodic gross Shear fracture extending f r o m the fr

Chip Formation in the Machining of Hardened Steel

M C Shaw (1) A Vyas, Arizona State University, Tempe, Arizona/USA

Received on January 4,1993

A b s t r a c t With the avai1abilit.y o f polycrystalllne cubic boron nitride (PCBN) i t i s possible t o machine vend hard gears, etc at speeds o f (60-150 m/min = 200-500 fpm) When

t h i s i s done using PCBN tools i n face milling, Chip formation i s of a cyclic saw toothed type This type of chip formation i s reviewed i n relation t o other types of

c y l i c and noncyclic chip formation The root cause o f high frequency, saw toothed chip formation i s found to be periodic gross Shear fracture extending f r o m the free surface of the chip toward the tool t.ip and not adiabatic shear as commonly believed

K e y w o r d s : Cutting, Cubic boron n i t r i d e (CBN), Chip formation

I n t r o d u c t i o n

With the appearance of superhard cutting tool materials i t

i s possible t o machine work materials such as case carburized

gears a f t e r heat treatment rather than by grinding (Hodgson and

Trendler,1901; Schwarzhofer and Kaelin, 1986; Koenig e t al,

1990) In the course of a general study of t h i s possibility some

very interesting cyclic chips have been obtained i n the practical

c u t t i n g speed range s i m i l a r t o ones described i n the l i t e r a t u r e

when machining materials of l o w e r hardness at very high speeds

In order t o optimize such machining operations, i t i s important t o

understand the chip forming mechanics of these cyclic chips i n

fundamental terms Before discusssing experimental r e s u l t s

obtained when face m i l l i n g case carburized steel specimens w i t h

polycrystalline cubic boron n i t r i d e (PCBN) tools, i t i s useful to

review c y c l i c chip formation from a broad point of Vie’w

Cyclic Chip Formation

Within a short t i m e a f t e r Merchant (1941, 1945) published

h i s w o r l d famous model of continuous chip formation (Fig la), i t

was suggested by several authors that a l l chips do not behave i n

accordance w i t h t h i s model I f the work i s relatively s o f t and not

prestrain hardened, chip formation w i l l involve a pieshaped zone

(Fig l b ) and an even more extensive shear zone i f the radius a t the

tool t i p (p) i s large relative to the undeformed chip thickness a

(Fig Ic)

Fig I Chip formation f o r - f l o w - type chips

a ) concentrated shear model f o r

Precoldworked softmaterial

b! Pie shaped shear zone for soft

annealed material

c) More extensive shear zone w i t h .::

subsurface plastic f l o w f o r tool

w i t h rounded t i p

rn

It was also soon discovered that a great deal o f c u t t i n g

involved c y c l i c chip formation The rnechanics of t h i s type of chip

formation has been thoroughly viewed by Komanduri and Brown

(198 1) and some important observations concerning t h i s topic

have been published by Nakayania (1974, 1988) Those interested

i n c y c l i c chip formation w i l l f i n d these three papers a valuable

s t a r t i n g point Only observs:ions that tixtend the concepts

presented i n these papers o r s h i f t the emphasis w i l l be presented

here

A l l types o f metal cutting involves fracture Even the

forma?ion o f continuous (so-called f l o w type) chips (Fig la)

involves extensive localized microfractures that do not extend

continuously across the w i d t h of the chip but are separated by regions undergoing subfracture p l a s t i c flow These microcracks are subsequently rewelded w i t h further deformation Evidence f o r

t h i s i s the fact that the mean shear stress-on the shear plane increases w i t h normal stress (Merchant, 1945) which would not be the case l f only p l s s t i c f l o w were involved Further evidence i s the presence o f the ends of localized microfracture planes on the back of a “ f l o w !ype” chip IFig.2) Since there i s no evidence of microfracture on the side surface of a continuous “flow” type chip, i t has been generally incorrectly assumed that no fracture i s involved

One of the f i r s t papers concerning cyclic Chip formation where the chip i s continuous but i s alternately thick and t h i n and rnOVeS i n a s t i c k - s l i p fashion up the face of the tool was described

by Bickel (1954) a t the ClRP General Assembly of t h a t year Bickel used a high frequency flash lamp t o produce a series of pictures showing the development of what i s generally referred to

as a wavy chip !Fig 3) This was the sit.uation f o r a r e l a t i v e l y

s o f t material machined at r e l a t i v e l y high but practical cutting speeds f o r the HSS and carbide tools then i n use As the chip was fot-med, the shear angle gradually decreased w i t h the chip stationary on the tool face u n t i l the component of force along the tool face was s u f f i c i e n t t o cause the chip t o move up the tool face

as the shear angle increased This was followed by the chip again Coming to r e s t and’a r e p e t i t i o n o f the cycle 01 variation In shear angle, forces and chip thickness With t h i s type o f chip there was

no gross fract.ure (i.e fracture where t.he plane of fracture extends clear across the ‘width of the chip) and when viewed f r o m the side, i t had the same appearance as a continuous “flow” type chip except that there were signs of greater and less s t r a i n having taken place I n the t h i n and thick chip v i c i n i t i e s respectively (Fig.3) S i m i l a r c y c l i c chips were described by Eugene (1957) a

short t i m e a f t e r Bickel Albrecht !I9621 has presented a discussion of wavy chip formation that involves the Cycllc variation of shear angle but no gross fracture

Fig 2 Back (free) surface of ‘flow’

type chip showing ends of rnicrorfracture planes

Fig 3 Wavy chip

A I I other c y c l i c Chip tormation involves periodic gross

fracture that extends clear across the w i d t h of the Chip Periodic

gross fracture may begin at the tool t i p o r a t !he free back surface

of the chip The f i r s t type which leads t o r e l a t i v e l y small

drsconnected segments i s generally termed discontinuous chip

formation

D i s c o n t i n u o u s C h i p F o r m a t i o n

Figure 4 shows cyclic chip formatjun where gross fracture

originates periodically from the tool t i p (A) The numbers under

the sketches are motion picture frame numbers The l a s t sketch

on the l e f t i s a composite showing how a single chip segment i s

formed I n t h i s case, the chip does not slide over the tool face as

i t is formed but r o l l s down upon t.he tool face as the center of the

chip i s extruded upward When frame 40 i s reached, the free

surface of the chip i s tangential t o the t.ool face and tool face

f r i c t i o n i s essentially zero a t the tool tip

Fig 4 Cyclic chip formation f o r Beta brass(after Cook et al; 1954)

Figure 5 shows the elastic stress pattern when a

concentrated horizontal force P is acting at the tool point (tool

face f r i c t i o n essentially zero) OF i s a line of constant shear

stress direction and since the magnitude o f the shear stress

rncreases as point 0 i s approached, OG o r a related l i n e curving

upward f r o m 0 and t o the left should be the fracture surface f o r

discontinuous chip formation The importance of tool face f r i c t i o n

being essentially zero when a new crack forms at 0 i s that tool

face f r i c t i o n a t 0 would give r i s e t o a compressive stress there

t h a t would tend t o prevent crack i n i t i a t i o n a t A i n Figure 4 The

condition that determines when a new gross crack forms at A i s

when the shear stress a t A i s high enough and the normal stress i s

l o w enough consistent w i t h the shear strength o f the material a t

A to cause fracture

P

Fig 5 Elastic stress pattern f o r cutting force P and zero tool face

f r l c t i o n force a t t l p of Sharp t o o l l a f t e r Marlelloti, 1941)

Fig 6 Situation when crack running from A t o E ext.endS below

path 01 c u t t i n g edge A-C

a) side v i e w b) top view showing crack region (gray)

and burniqhed cut region (shiny)

Eased on the foregoing sequence of events leading to

discontinuous chip formation i t IS t o be expected, as observed,

that the size and shape o f each segment will be auuroxlmately the

same f o r a reasonably homogeneous work mat.erial Figure 6 shows the situation when the fracture curve extends below the

l i n e of tool t i p travel This i s then a source of surface roughness

f o r discontinuous chip formation and the finished surface w i l l consist of alternale unburnished (dull) and burnished (shiny) regions when the finished surface i s viewed from above (Fig 6b) cast i r o n and unleaded 70130 o r 60/40 brasses are materials that tend t o give discontinuous chips that are easily disposed of I t i s found that the s t i c k - s l i g freauency of segment formation i s influenced i n a minor way by the s t i f f n e s s of the tool-work machine tool system

Saw T o o t h Chip F o r m a t i o n Still another type of cyclic Chip i s obtained w i t h cold worked 60/40 brass Figure 7a shows a Chip root f o r such a material w h i l e Figure 7b i s a diagrammatic interpretation In t h i s case, perlodic gross fracture occurs at the free surface where normal stress on the shear plane i s zero and runs clear across the surface t o the tool t i p In Figure 7a a new crack i s l u s t about t o occur and run t o the tool tip Nakayama

reasons why FG i s parallel t o the resultant

(1988) has given good force (R) on the tool

Fig 7 a) Optical Photomicrograph o f p a r t i a l l y formed continuous

chip of60/40 cold worked brass (rolled to 60% reduction

i n area before cutting) Rake angle = -150; undeformed chip thickness O.16mm (.0063 in), cutting speed = 0.075 m min-1(2.95 ipm) (Nakayama, Toyama Universit-y)

b) diagrammatic representaion of a)

As soon as a crack runs f r o m B t o A i n Figure 7b material

i s displaced f r o m cross hatched region 1 1.0 2 w i t h further advance

of the tool This forces the block of material A B W outward t o i t s

rinal position EFGD w i t h essen!ially no deformation except f o r

that associated w i t h f r i c t i o n sliding along AB, DG and the tool

face AH In the case o f Figure 7, f r i c t i o n on the tool face i s

r e l a t i v e l y low and the resultant force on !he tool i s approximately horizontal and the fracture angle 4 i s 45O The f a c t that the direction o f the cold worked f l o w lines i n Figure 7aremains unchanged i n the uncut material and i n the bulk o f the chip i s consistent w i t h the foregoing mechanism (Nakayama 1988)

The work done i n t h i s type of chip formation w i l l involve

f r i c t i o n a l sliding resistance along planes AB and 0 6 and tool face

AH plus a r e l a t i v e l y small amirunt o f extrusion related energy associated w i t h the displacement of material from 1 t o 2 (Fig 7b)

.A new fracture plane w i l l develop when the total sliding distance i s s u f f i c i e n t t o again produce the fracture stress a t the free surface The dotted planes 8'A' etc are subsequent fracture planes which w i l l be uniformly spaced f o r a homogeneous work material It should be noted that i n Figs 7 the sliding that occurs i s l i k e t h a t of a f r i c t i o n slider w i t h essentially zero subsurface p l a s t i c f l o w

Fig.8 Optical photomicrographs of Coninuirus titanium chips a) st low cut.ting speed of 25 mm/min ( 1 ipm)

b) a t relatively high cutting speed o f 53 m/min (175 fpm)

c i diagrammatic interpretation of b) ( a f t e r Shaw etal, 1954)

Figure 8a shows a t i t a n i u m chip produced at low speed

where a saw toothed chip i s produced due t o shear fracture

surfaces running periodically i r o m the free surface t o the tool t i p

i n the manner of Figure 7 Here the m a j o r expenditure of energy i s

again involved i n overcoming sliding f r i c t i o n along the tool face

and fracture surfaces L i t t l e evidence of p l a s t i c f l o w i s evident

w i t h i n the segments Figure 8 b shows the chip produced f r o m the

same material but a t a more normal cutting speed 153 m / m i n (175

fpm)] Several differences between 8a and 8b are evident:

0 There i s considerable secondary deformation along the

tool face i n Figure 8b but not i n 8a

The secondary deformation along the tool face i s

very inhomogenenus i n Figure 8b

There i s evidence of considerable subsurface deformation

along the fracture surfaces i n Figure 8b

C o m p o s i t e Chip F o r m a t i o n

Figure 8c shows a diagrammatic interpretation of Figure

8b I n this case, gross fracture extends only part way to the tool

tip The gross fracture crack w i l l be stopped a t a point where the

compressive stress on the shear plane reaches a ralue s u f f i c i e n t l y

high t o stop the crack This rneans that the layer below the

stopped crack must be removed by the flow type cutting

mechanism while the upper part involves sliding f r i c t i o n a l

resistance Deformation i n the secondary shear zone along the

t o o l face i s very inhomogeneous There i s evidence of unusually

large p l a s t i c s t r a i n i n the secondary shear zone along extensions

of the gross shear cracks (indicated by dots in Figure 8c) This

suggests that weakening associated w i t h the generation of

noncontinuous microcracks along the dotted crack extensions

shown in Figure 8c i s responsible for the concentrated shear bands

i n the secondary shear zone

The shear bands eviden! i n Figure Rb l i e along the shear

fracture planes and are evident when materials having l o w

thermal properties (conductivity and volume specific heat) are cut

at r e l a t i v e l y high speeds A t high speeds of sliding, considerable

thermal energy develops and w i t h l o w thermal properties, t h i s

results i n thermal softening and considerable subsurface f l o w

along the sliding f r i c t i o n (fracture) surfaces These concentrated

shear bands are frequently referred t o as being due t o adiabatic

shear While t h i s i s true enough regarding the end result,

adiabatic shear i s not the root cause of t h i s type o f cyclic Chip

formation but merely evidence of the presence o f high thermal

energy due t o high speed sliding along already formed periodic

fracture surfaces The cyclic formation of these fracture

surfaces i s the actual cause of the i n s t a b i l i t y and not adiabatic

shear as suggested by Shaw e t al (1954) Saw tooth chips are

obtained w i t h (Fig 8b) and without (Fig 8a! the presence of

adiabatic shear

When a titanium rrlloy i s cut a t extremelu l o w speed (-0.001

rn/min = 0.004 fpm) continuous chips of the type shown i n Figlire 4

w i t h individual segments welded together are obtained !Komanduri

and Turkovich, 1981) In t h i s case, periodic fracture begins a t the

tool tip However, a t more practical speeds but as l o w as

2 5 mm/min [ I ipm]) chip format.ion i s as shown i n Figure 8 w i t h

periodic lractiure st-arting at the free surface as suggested by

Nakayams ( 1 988)

Kornanduri and tiis associates have obtained turning chips

very s i m i l a r to that of Figure 8b when cutting materials having

l o w thermal properties a t very high speeds Figures 9a and 9b are

two examples Figure 9a is a saw toothed chip produced when

machining AlSl 4340 steel of moderate hardness (% = 325

Kg/mm*) a t a high speed 250 m/min (800 f p m i This i s seen to be

s i m i l a r t o Figure 8b except !hat the very high speed of sliding

along the extensions o f the gross fracture surfaces !dots i n Fig

8c) and along the tool face results i n what appears t o be melting

as indicated by the whit.e [unet-ched ) bends i n Figure 9a Figlure

9a shows periodic m e l t i n g a t points A, 6, C, etc along the ton1

face As Komanduri has suggested, the speed of the chip

luctuates periodically and w i l l have i t s maximum velocity j u s t

a f t e r gross fracture occurs This appears t o correspond t o the

regions of greatest depth o i melting where the r a t e o f heat

g e n m t i o n will be B maximum A t higher cutting speeds than that pertaining i n Figure 9a an w e n thicker w h i t e layer was evident along the tool face

Figure 9b shows a saw toothed chip produced when turning a nickel base tlirbine alloy at what i s 8 high speed f o r t h i s material The chip of Figure 9b i s very s i m i l a r t.o !.hose o f Figures 8b and 9a From Figure 9c i t i s evident that when periodic gross cracks

do not penetrate a l l the way t o the t.ool tip, t w o t-ypes o f chip formrjtion are superimposed - that COrreSpOnding to Figure 7b

where sliding f r i c t i o n i s predominant and that corresponding t o

very nonhomogeneous f l o w type chip iormat.ion w i t h extensive secondary s h e w flow along the tool face

Lindberg and Lindstrom (1983) studied saw toothed chip

formation of A l S l 1035 steel and found that saw toothed chips were not formed even at very high speeds if the undeforrned chip thickness (feed) had a low value For examDle, saw toothed chips were formed a t a frequency of about 14000 Hertz a t a cutting Speed of 150 m / m i n (490 fpm), a feed of 0.315 m m i r e v (0.012 ipr)and a depth of cut of 2 rnm (0.080 in) but continuous chips were formed a t the same speed and depth of cut when the feed was reduced to 0.100 mm/rev (0.004 ipr) Since the highest natural frequency of any of the components of the tool-work-machine tool systern i s only about 1000 Hz, i t follows that the stiffness o f the System shoulU have no influence on the frequency of segment formation This has been found t o be so for a l l cases of saw tooth chip formation (Komanduri e t 81, 1982)

n e l t i n g This Is not the f i r s t t i m e what i s believed to be a molten layer has been observed i n metal cutting Schaller (1962) in studying the machining of specially deoxidized steels having a

l o w tendency t o cause cratering o f carbide tools a t high cutting speeds has observed a nonetching w h i t e layer along the tool face (Fig 10) This appears t o be a material that has melted and then cooled so rapidly that an unresolvable grain size o r none at a l l (amorphous) develops In t h i s case relatively low melting ternary (Si$-AI,O,-CuO inclusions spread over the tool face and act as

a diffusion barrier

Fig 4 U p t i i a l photomicrographs of continuous saw toothed chips produced when machining d i f f i c u l t materials a! high speel

a) AlSl 4340 steel (Hg = 325 z HRC = 34) turned w i t h AI,O,/Ti ceramic tool at cutting speed of 250 m/min !800fprn), feed of O.Smm/rev.(O.O I8 ipr),depth

o f clut of 3.75 mm (0.1 Soin), rake angle of - 5O no cutting f l u i d ( a f t e r Kornanduri e t al, 1982)

b! Solution t-reated and aged lnconel 718 (y= 300 s

4 3 ) nickel based turbine alloy turned w i t h

A1,0, /TIC ceramic tool at cut.ting speed of 92 m i m i n (300 fpm), feed of O.2Omm (0.008 ipr), dept.h o f cut of 2.5 mm (0.100 in!, rake angle, -5O no c.utt.ing f l u i d ( a f t e r Komanduri and Schroeder, 1’3861

DeSalvo and Shaw (1969) have investigated the possibilities

what a t first glance appears to be a f i l m that i s inclined i n the

wrong direction f o r positive hydrodynamic pressure development

w i l l actually give positive pressure This becomes clear by

reference t o Figure I 1 Figure I l a shows the classical slider

bearing w i t h a stationary inclined pad and an extensive member

moving w i t h a velocity V to the l e f t w h i l e Figure 1 l b shows the

chip moving parallel t o the stationary tool Figure 1 IC i s the

kinematic equivalent o f Ilb which i s seen t o be identical t o Ila

of hydrodynamic action w i t h such a situation and have shown that of I

Fig 10 Formation of l a y e r on tool face when turning specially

deoxidized steel a t high speed ( a f t e r Schaller, 1962)

Venuvinod e t a l (1983) have also found a structureless

w h i t e layer when using an externally driven r o t a r y tool to turn

m i l d steel The presence of such a f i l m led to l o w force levels

which were a t t r i b u t e d to hydrodynamic action No such f l u i d

f i l m s were found f o r m a t e r i a l s having higher thermal

conductivity (Cu, Al, brass)

The unetched w h i t e layers i n Figure 9 represent a t h i r d case

i n metal c u t t i n g where molten layers appear t o be involved No

l e g i t i m a t e evidence of melting i n grinding exists even though the

specific energy in fine grinding i s more than an order o f

magnitude greater than that f o r metal cutting (Shaw, (1984)

A t c u t t i n g speeds even higher than those f o r Figures 9a and

9b the chips are no longer continuous (Komanduri e l al, 1982) but

consist of individual segments This i s apparently due t o m e l t i n g

of a continuous layer separating individual segments

Fig 1 1 a) Classical hydrodynamic s l i d e r bearing w i t h f l u i d layer

decreasing i n thickness i n direction of motion

b) Inclined 'fluid' layer between stationary tool and s o l i d

chip surface moving parallel t o tool face

c) kinematic equivalent of b) which i s the same as a)

Milling H a r d Case C a r b u r i z e d Steel

When case carburized A l S l 8620 steel (b = 61 and 0.050 i n

case depth ~ 1 2 5 mm) is subjected t o a plane m i l l i n g operation

under the following conditions, saw-toothed chips very s i m i l a r t o

those in Figure 3 are obtained (Fig 12):

Cutting speed: 500, 200 fpm (152, 6 1 m/min)

Depth of cut: 0.010, 0.005 i n (0 25, 0.13 mm)

Feed: 0.0 10, 0.005 i p r (0.25, 0.13 mm/rev)

Rake angle: -7

Tool: Five PCBN inserts each 0.500 x 0.188 i n (12.5 x

4.80 mm), 0.031 in (0.78 mm) nose radius, 3 i n

c u t t e r diameter (76mm) 80"x100" diamond shaped inserts w i t h 100' corner used

These chips are seen t o h a w t.he same appearance as those 'igure 9 including the following:

periodic gross cracks extending part way from free slurface of chip t.o tool t.ip

0 very Iit-tle evidence of plastic f l o w i n t.he "teeth' of the

chip

0 heavy p l a s t i c f l o w i n ?he region of the chip below the extent of gross cracks and along the tool face

0 w h i t e unetched layers along ?he too! face and gross frac!ure surfaces

Fig 12 a) Optical photomicrograph of continuous saw toothed chip

produced when face m i l l i n g case carburized steel (61

kl a t cutting speed of 500 fpm (152 m/min), feed of 0.0 10 i p r (0.25 mm/rev), depth o f cut 0.0 10 i n (0.25

mm), rake angle of - 7,and using no cutting fluid b) Scanning electron micrograph o f portion of a) a t 5x the magnification

Chips produced a t other feeds and speeds were s i m i l a r t o those of Figiure 12 The material i n the w h i t e layer along the tool face in Figure 128 i s seen t o be essentially wihout structure This was even found t o be the case in SEN micrographs of the w h i t e

layer at 3500~

Figure 8c holds equally w e l l f o r Figures 9, 8b and 12 When

the gross cracks extend only part way t o the tool t i p there are t w o shear angles Q:

9, = the gross fracture plane shear angle (459)

0 +2 = the p l a s t i c defomation shear angle f o r the f l o w type chip formation region ( @ 2 < Q,)

Also, i n Figure Eic, p i s the spacing of successive gross fracture planes on the work surface and pc i s the corresponding spacing on the chip (p>p,) The cutting r a t i o for such a composite model

w i l l be

As Nakayama !I3881 has shown, the resultant force on the tool face i s as shown in Figures 8a and 9 and the included angle at the

t i p o f each "tooth" should be 4S0 as indicated in Figure 9

C o n c l u d i n g Remarks

Considerably more information may be extracted by

examination of a saw tooth chip than f r o m a cant-inuous f l o w type

LhiP but t o consider t h i s would carry the present, diSclJSsion too

f a r a i l e l l j The main objective of t h i s paper was t o demonstrate

!hat Saw tooth chips are obtained no! onlq when

a highly cold wYorked b r i t t l e material i s machined even a t

l o w Speeds [Fig 7 f o r brass)

a a d i f f i c u l t t o machine material w i t h low thermal

properties (k, pc) i s niachirted over a wide range of

speeds (Fig 8, T i ) and Fig 9b (Ni base alloy

a a somewhat d i f f i c u l t to machine material and moderate

hardness i s machined at very high Speed (Fig.98,

AlSl 4340 steel)

but also when

0 a very nard b i t t l e material i s machined at relatively l o w

speed (Fig 12 - case caburized hard steel)

A second objective was t o show the relationship of saw

tooth chip formation t o other modes of cyclic chip lormation as

w e l l as t o f l o w type Chips A l l types o f chip formation involve

fracture as w e l l as plastic flow The f l o w type chip involves

localized microfracture and rewelding i n conjunction w i t h p l a s t i c

f l o w &haw et al, 1991) I t i s important t o keep this i n mind

when attempting analytical simulation of any chip forming

process Use of the Von Mises f l o w c r i t e r i o n i s inadequate as a

constitutive relation even f o r f l o w type chip formation and i s

particularly inadequate f o r cyclic Chips, since i t does not take the

important fracture aspect i n t o account

An important r e s u l t i s t h a t what appears t o be a liquid layer

of chip rnaterial i s formed along the tool face when a very hard

b r i t t l e material such as hardened case carburized steel i s

macnineu a t ordinary speeds This means that the contact area

between Chip and tool w i l l be 100% of the apparent area of

contact This coupled w i t h the very high temperature involved

(M.P of work material) greatly increases the likelihood of crater

wear on the tool face Polycrystalline CBN i s w e l l suited t o the

machining of superhard work materials because o f i t s hardness,

chemical s t a b i l i t y i n contact wit.h high tmperature i r o n and i t s

outstanding thermal properties

R e f e r e n c e s

A1brecht.P (1962) Self Induced Vibrations i n M e t a l Cutting,

Bicke1,E ( 1 954) Hochlrequenten Zeitlupenaufnahmen (Spanbildung)

Cook,N.H.; Finnie, 1.; and Shaw, M C (19543 Discontinuous Chip

Formation, Trans ASME a 153-162

DeSalvo, G.J and Shaw, M.C 11968) Hydrodynamic Action a t Chip-

Tool Interface, Advances i n Pergamon P r e s s 2 96 1-97 1 m Tool -

Ernst, H J and Merchant, M C (1941), Chip Formation, Friction,

and Finish, Trans Am SOC Metals 29,299

Eugene, E (1957) Etude Experimentale sur I'lnfluence Conjointe de

la Pente D'Affutage de I'Outil et de la Vitesse de Coupe sur

les Modalites de l a Formation de Copeau, Annals of CIRP

A 121

Hodgson, T and Trendler, P.H.H (198 I ) Turning Hardened Tool Steel

w i t h Cubic Boron Nitride Inserts, &&&J&, r m 6 3

Koenig, W.; Klinge, M.; Link, R (1990) Machining Hard Materials

w i t h Geomtrically Defined Cutting Edges - Field of

Applications and Limitations, Annals of CIRP 59/1.61-6

Komanduri, R and Brown, H (1981) On the Mechanics of Chip

Segmentation i n Machining J Ena f o r lnd (Trans m,

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Annals of CIR P 3.90-9 1

Kornanduri, R and yon Turkovich ( I 9 8 1 New 0bSerVat.ions on the

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Komanduri,R; Schroeder, T.A., H a p , J; von Turkovich, 6.F; (198 1 )

New obsevations on the Mechanism of Chip Formation When

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(Trans.ASME) 104- I2 1 - I 3 I

Advanced M a m n i n g Research Program, J Eno f o r InU

(Trans ASME) 107 325-335

Komanduri, R and Schroeder, T.A (19863 On Shear Instability i n machining a Nickle-Iron Base Superalloy

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Komandluri, R.; Flom, 0 G., and Lee, m ! 1'?851 Highlights of DARPA

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