0 WZL/Fraunhofer IPTCutting materials, tools and coolants for
machining with geometrically defined cutting edges part
1Manufacturing Technology ILecture 4Laboratory for Machine Tools
and Production EngineeringChair of Manufacturing TechnologyProf.
Dr.-Ing. Dr.-Ing. E.h. F. Klocke1Seite 1 WZL/Fraunhofer IPTContents
of the lectures 4 and 5 tool steels cemented carbides coatings
ceramics tool design cooling lubricants Lecture 4 Lecture 52Seite 2
WZL/Fraunhofer IPTStructure Introduction classification according
to hardness and toughness nomenclature and classification of
cutting materialsTool steelsCemented carbidesCoatingsSummary3Seite
3 WZL/Fraunhofer IPTMain requirements on tool materials Hardness
Abrasion Toughness Heavy cuts ( high feed values and depth of cut,
high cutting forces) Interrupted cuts High dynamics Heat resistance
Diffusion High cutting speed (heat generation) Heat shock
resistance4Seite 4 WZL/Fraunhofer IPTClassification of cutting
materialstoughness, flexural strength and feedCutting speed,Wear
resistance, thermal resistanceDPoptimal cutting material1BN1 in
consideration of hardness2 in consideration of hardnessand
temperatureDP:2fine and ultra fine graincementedcarbideAl2O3+
TiCCermetcoatedCermetCoated cemented carbideSi3N4-ceramicAl2O3
-ceramiccemented carbide basedon tungsten carbidecoated
HSSHSS5Seite 5 WZL/Fraunhofer IPTClassification of cutting
materialscold working steelhigh speed steelWC-CoTiC/TiN -
Co,NiWC-(Ti,Ta,Nb)C-Cooxide ceramicsilicium-nitride
ceramiccomposite ceramicsboron nitridediamondtool steelcemented
carbidesceramicssuper hard cuttingmaterialscutting materials for
processing with geometrically defined cutting edge6Seite 6
WZL/Fraunhofer IPTApplication GroupsP Group WC-(Ti,Ta,Nb)C-Cohigh
heat resistance, reduced toughnessMGroupKGroup(WC, Co)high
toughness, reduced heat resistance7Seite 7 WZL/Fraunhofer
IPTcemented carbidesdenotation cemented carbide groupHWuncoated
cemented carbide, main content tungsten-carbide (WC) with grain
size 1 mHT 1)uncoated cemented carbide, main content titanium
carbide (TiC) or titanium nitride (TiN) or bothHC cemented carbide
as above, coated1)these cemented carbides are also called
"Cermets"HFuncoated cemented carbide, main content tungsten-carbide
(WC) with grain size < 1 mClassification and application of hard
cutting materials (DIN ISO 513)8Seite 8 WZL/Fraunhofer
IPTClassification and application of hard cutting materials (DIN
ISO 513)ceramicdenotation group of ceramicCAoxide ceramic,major
content aluminum oxide (Al2O3)CMcomposite ceramic, major content
oxide ceramic(Al2O3), also non-oxide ceramicCNnitride ceramic,
major content silicon nitride (Si3N4)CRoxide ceramic,major content
aluminum oxide (Al2O3)reinforcedCCoxide ceramic as above, but
coateddiamonddenotation diamond groupDPpoly-crystalline diamond
DMmono-crystalline diamondboron nitridedenotation boron nitride
groupBLcubic-crystalline boron nitride with low content of boron
nitrideBHBCcubic-crystalline boron nitride with high content of
boron nitridecubic-crystalline boron nitride as above, but
coated9Seite 9 WZL/Fraunhofer IPTdenotation colorP blueMKhard
cutting materialsapplication groupwork piece
materialyellowredP01P10P20P30P40P50P05P15P25P35P45M01M10M20M30M40M05M15M25M35K01K10K20K30K40K05K15K25K35aincreasing
wear resistance of the cutting material, increased cutting speeds
possiblebincreasing toughness of the cutting material, increased
feed rates possibleaaabbbmachining main group (Source: DIN ISO
513)steel:all kinds of steel and cast steel,except rustproof steel
with austenitic microstructurestainless steel:stainless austenitic
and austenitic-ferriticsteel and cast steelcast iron:cast iron with
flake graphite, cast iron with spherical graphite, annealed cast
ironApplication of cutting materials (DIN ISO 513)10Seite 10
WZL/Fraunhofer IPTApplication of cutting materials (DIN ISO
513)NSHgreenbrowngreyN01N10N20N30non-ferrous metal:aluminum and
other non-ferrous metals, non-metal work
materialsN05N15N25S01S10S20S30special alloys and
titanium:high-temperature special alloys based upon iron, nickel
and cobalt, titanium and titanium alloysS05S15S25H01H10H20H30hard
work materials:hardened steel, hardened cast iron materials,
chilled cast ironH05H15H25denotation color hard cutting materials
work piece materialaaabbbmachining main group (Source: DIN ISO 513)
application groupaincreasing wear resistance of the cutting
material, increased cutting speeds possiblebincreasing toughness of
the cutting material, increased feed rates possible11Seite 11
WZL/Fraunhofer IPTStructureIntroduction Tool steels unalloyed tool
steels alloyed tool steels high speed steel (HS)Cemented
carbidesCoatingsSummary12Seite 12 WZL/Fraunhofer IPTMain design
features of tool steelsOrdinary tool steelsMatrix: Martensite,
primary carbidesHigh speed steelMatrix: Martensite, primary
carbides, secondary carbides13Seite 13 WZL/Fraunhofer IPTExamples
of unalloyed cold working steelsunalloyed cold working
steelcomposition [%] applicationC Si Mn Cr Mo V Whammer, axe,
shear, screw driver, chiselwood saw, hand saw, solid of composite
saw bladesfile, scraper, paper shearall kind of chiselsfile,
scraper, paper shearcutting tools, shear for steel cutting,
broaching
tools0,80-0,900,25-0,400,50-0,701,20-1,350,10-0,300,10-0,35-0,500,40-0,400,15-0,800,600,42-0,470,20-0,300,85-1,01,7-1,90,25-0,30
0,051,10-1,250,15-0,300,20-0,400,5-0,8--0,07-0,120,15-0,452,0-2,250,10-0,4011,0-12,0----0,6-0,8C45W1.1730C85W1.1830C125W1.156345CrMoV71.2328115CrV31.2210X210CrW121.2436alloyed
cold working steeldenotationNr.14Seite 14 WZL/Fraunhofer
IPTVariations and applications of high speed steelscutting steel
atmedium load maximum loadcompo-sitiondenotationW - Mo - V - Co<
850 N/mm2 > 850 N/mm2 roughing finishing18% WHS18-0-1HS18-1-2-
5+----+--12% WHS12-1- 4- 5HS10-4- 3- 10----(+)(+)++6% W + 5%
MoHS6-5-2- + - -HS6-5- 3- - (+) +HS6-5-2- 5- - + -2% W + 9%
MoHS2-9-1HS2-9-2HS2-10-1-8+---+---+---IIIIIIIVHigh-speed steels are
notated with the letters HS and the indication of the
percentalamount of alloying additions inthe sequence W-Mo-V-Co,
e.g. HS10-4-3-10. The classification of high-speed steels is raised
by their W- and Mo-concentraion intofour alloy- and performance
groups.15Seite 15 WZL/Fraunhofer IPTMain applications of the most
important high speed steelssteel groupdenotation according toDIN EN
ISO
4957HS6-5-2HS6-5-3HS6-5-2-5HS10-4-3-10HS2-9-2HS2-9-1-8mater-ialNr.1.33431.33441.32431.32071.33481.3247applicationstandard
material for roughing and finishing, twist drills, tapping tools,
milling tools, broaching tools, reaming tools, countersinker,
hobbing tools, saws, forming toolshigh performance tapping and
reaming tools, high performance millingtools, broaching tools,
twist drillshigh performance milling tools, turning and hobbing
tools, high performancetwist drills and tapping tools, cold working
tools, roughing tools with high tenacityuniversal roughing and
finishing tools, turning and high performance millingtools, free
cutting steel, tools for wood machiningtwist drill and tapping
tools, milling tool, reaming tool, broaching toolend milling tools,
turning tools for free cutting operations, twist drills, tapping
tools16Seite 16 WZL/Fraunhofer IPTProduction of high speed steel by
melting02004006008001000120014001600melting and foundingblock
turningblock annealing forging rolling final annealingtemperature T
/ Ctime t / hdenotation HS18-1-2-5 HS10-4-3-10 HS12-1-4-5 HS12-1-4
HS6-5-2hardening temperature C 1280 1240 1240 1240 1230annealing at
0,5 1 h3 560 C2 570 C1 550 C2 570 C2 560 C2 540 C17Seite 17
WZL/Fraunhofer IPTHeat treatement of high speed steel1. annealing2.
annealingoil / airair air air airheating in vacuum furnaceannealing
time in each case: 1 2 htime t / hslow furnacedown
coolingtemperature T / Ccompensating
temperatureheatingaustenizeannealingstress relief annealingpre
machiningfinishing3. annealingABCDEFGA 600 - 650 C B 1. pre-heating
stage ca. 400 C (in salt bath)C 2. pre-heating stage 850 C D 3.
pre-heating stage 1050 CE hardening temperature ~1200 CF salt bath
500 - 600 CG 50-80CTo realize their endhardness HSS-Tools are
preapared by a heattreatment. In a first stepthey are hardend (
heated, held on austenite temperature and cooled down with high
speed), afterwards several times tempered. 18Seite 18
WZL/Fraunhofer IPTTemperature dependent effects on the hardness in
tempering HS~ 600 ASMA1A2M1M2~ 66 temper temperature T / Chardness
/ HRCTempering of high-speed-steel takes place bei temperatures
between 540 580 C and isfor this reason in the temperature range of
secondary harndess. This pickup of hardnessleads under normal
hardening- and temperconditons to hardness values, which can
beclearly higher then these after quenching.The cutting material
hardness resulting from the overlay of the different processes
isshown as a sum graph S depending on the tempering
temperature.19Seite 19 WZL/Fraunhofer IPTTools made of high speed
steel - examplessource: Forstsource: Sandviksource: PWStools for
gear shapingcylinder gearspline shaft chain wheelinternal gear
broaching tools forinternal broachingexternal broachinghard
broachingtools fordrillingmillingtapping thread millingthread
forming20Seite 20 WZL/Fraunhofer IPTStructureIntroductionTool steel
Cemented carbide WC-Co-based cemented carbide (HW) TiN/TiC-based
cemented carbide cermet (HT) fine grain cemented
carbideCoatingsSummary21Seite 21 WZL/Fraunhofer IPTMilestones in
the development of cemented carbidespatent for manufacturing of
WC.Co-HM,K. SchrterSpring Fair Leipzig: 1. WC-Co-HMManufacturer
Krupp, Denotation WIDIACarboloy (General Electric)WC-TIC-Co
cemented carbidesTiC-Mo2C-Ni (1. cermet-generation )Manufacturer
Plansee, denotation Titanit STitanit (Plansee), Bhlerit
(Bhler)Coromant (Sandvik)presentation of coated cemented
carbidesfine grain Spinodal - Cermet ( 1. Cermet with TiN
)increased development of Cermetsultrafine and nanocrystalline
grainhardness HV30flexural strength N/mm2mean grain diameter
mstandard (1,4 - 1,8)fine grain (< 1)ultra fine grain (<
0,5)uncoatedmulti layer0 1000 2000 3000 4000tool
life1923100%360%19271928193119341937194268/691970197373/741993(
)22Seite 22 WZL/Fraunhofer IPTProduction process of cemented
carbide components23Seite 23 WZL/Fraunhofer IPTInfluences on wear
resistance and toughness of cemented carbidesWith regard to the
wear- and performance abillity of uncoated and coated
cementedcarbides the features of cemented carbide substrates play a
key role24Seite 24 WZL/Fraunhofer IPTMicrostructure of conventional
cemented carbide and cermetIn conventional cemented carbides based
on WC the tungsten carbides mostly exist in prism shape with a
triangular base. The carbide skeleton is filled up with the
bindingphase. The structure of cermets is only made of chamfered
mixed carbonitrides. Characteristiclyfor their microstructure is
the core-shell-structure of the hard material.25Seite 25
WZL/Fraunhofer IPTComposition and properties of conventional WC-Co
cemented carbidescemented carbide classificationsource: DIN ISO
513HW - K05 HW - K10 HW - K25 HW - K40sort WC - 4Co WC - 6Co WC -
9Co WC - 12Co15,1 14,9 14,6 14,21730 1580 1420 12905700 5400 5000
45001600 2000 2350 2450650 630 590 5806,9 9,6 12,3 12,70,21 0,22
0,22 0,2280 80 70 655,0 5,5 5,6 5,9source: ISO 3369source: ISO
3878source: ISO 4506source: ISO 3327source: ISO 3312density /
(g/cm-3)hardness HV 30compression strength(cyl.-specimen) /
(N/mm2)flexural strength / (N/mm2)Youngs Modulus/
(103N/mm2)fracture toughness / (Nm1/2/mm2)Poisson ratiothermal
conductivity / (Wm-1K-1)thermal expansion coefficient (293 K1073 K)
/ (10-6K-1)Cemented carbides of this group exist almost completely
out of hexagonal tungstenmonocarbide and the binding phase cobalt.
They can contain up to 0,8 mass% VC and/orCR3C2 and/or up to 2
mass% (TaNb)C as doping additives to controle the grain size and
constancy.26Seite 26 WZL/Fraunhofer IPTMicrostructure of micro
grain and sub micro grain cemented carbidesturning of chilled cast
iron( 80 shore )024681014mintool lifestandard micro grain sub
micronstandardmicro grainsub micronWC - 6-Co carbides(H): hardness
HV30(B): flexural strength N/mm2source: Krupp Widiavc = 16 m/minf=
0,1 mmap = 1,0 mminsert:SPGN 120308sharp cornered,= 7527Seite 27
WZL/Fraunhofer IPTDependency of grain size, hardness and
toughnesssource: Widia nano: < 200 nm fine:0,8 - 1,3 m super
fine: 0,5 - 0,8 m ultra fine: 0,2 - 0,5
m1000120014001600180020002400hardnessHV30500100015002000250030004000flexural
strengthN/mm4 6 8 10 12 16cobalt content / % 1428Seite 28
WZL/Fraunhofer IPTCutting edge after hard milling 55
HRCconventional cemented carbide 9.5% Comilling time 90 minultra
fine cemented carbide 7.5% Comilling time 175 min29Seite 29
WZL/Fraunhofer IPTApplication of ultra fine grain cemented carbide
- micro millingwork piece: X5CrNi18-10cutting speed: 6
m/minrevolutions: 8000 min-1feed per tooth: 1 to 5 mdepth of cut:
64 mwidth of cut: 254 m1 mm30Seite 30 WZL/Fraunhofer IPTComposition
and properties of WC-(Ti,Ta,Nb)C-Co cemented carbidescemented
carbide classification source: DIN ISO 513HW - P10 HW - P15 HW -
P25 HW - P30 HW - M10 HW - M15composition (mass-%)WC(Ti, Ta,
Nb)CCo31,060,09,025,564,510,017,372,710,010,078,511,59,584,56,011,082,56,510,6
11,7 12,6 13,0 13,1 13,31560 1500 1490 1380 1700 15504500 5200 4600
4450 5950 55001700 2000 2200 2250 1750 1900520 500 550 560 580
5708,1 9,5 10,0 10,9 9,0 10,50,22 0,23 0,22 0,23 0,22 0,2225 20 45
60 83 907,2 7,9 6,7 6,4 6,0 6,0source: ISO 3369source: ISO
3878source: ISO 4506source: ISO 3327source: ISO 3312density /
(g/cm-3)hardness HV 30compression strength(cyl.-specimen) /
(N/mm2)flexural strength / (N/mm2)Youngs Modulus/
(103N/mm2)fracture toughness / (Nm1/2/mm2)Poisson ratiothermal
conductivity / (Wm-1K-1)thermal expansion coefficient (293 K1073 K)
/ (10-6K-1)Cemented carbides of this group contain besides tungsten
mixed carbides (MC) out of titanium- tantalum- niobium- and/or
zirconiumcarbide. Compared to the WC-Co-cemented carbides they show
improved high temperature abbilities.31Seite 31 WZL/Fraunhofer
IPTsource: Pulvermetallurgie der Hartmetallecermet group source:
DIN ISO 513HT P05 HT P10 HT P20composition (mass-%)carbon
nitrideadditional
carbidesCo/Ni89,00,610,485,70,813,582,31,016,7source: ISO 33696,1
7,0 7,0source: ISO 38781650 1600 1450source: ISO 45065000 4700
4600source: ISO 3327 2000 2300 2500source: ISO 3312 460 450 4407,2
7,9 10,00,21 0,22 0,219,8 11,0 15,79,5 9,4 9,1density /
(g/cm-3)hardness HV 30compression strength(cyl.-specimen) /
(N/mm2)flexural strength / (N/mm2)Youngs Modulus/
(103N/mm2)fracture toughness / (Nm1/2/mm2)Poisson ratiothermal
conductivity / (Wm-1K-1)thermal expansion coefficient (293 K1073 K)
/ (10-6K-1)Composition and properties of CermetsIn comparison with
conventional cemented carbides cermets show a lower density.
Significant differences compared to WC-based cemented carbides are
the clearly lowerheat conductivity and at the same time higher
thermal extension.32Seite 32 WZL/Fraunhofer IPTTurning of steel
using cermetsDue to the high edge strength, the high resistance
against abrasive wear, and littleadhesive wear cermets are
particularly suited for finishing steels.33Seite 33 WZL/Fraunhofer
IPTMilling with Cermetsend mill,carbide K25Pend mill,cutting speed
vc34Seite 34 WZL/Fraunhofer IPTApplication of different cemented
carbide qualitiesWC-Co-carbide: + high hardness and wear resistance
because of tungsten carbide(K-group) + high edge toughness because
of high solubility of WC in the WC-Co binder- reduced heat
resistance because of diffusionWC-(Ti,Ta,Nb)C-Co: + high heat
resistance, resistance against oxidation and (P-group) diffusion
because of high content of TiC, TaC and NbC- reduced edge toughness
because of poor solubility of carbidesin the bindercermet (TiC/TiN)
: + high heat resistance, high resistance against oxidation and
diffusion + high surface quality because of low adhesion - low
toughness- low thermal shock resistance35Seite 35 WZL/Fraunhofer
IPTStructureIntroductionTool steelCemented carbide Coatings
Chemical vapour deposition (CVD) Physical vapour deposition
(PVD)Summary36Seite 36 WZL/Fraunhofer IPTWear phenomena on coated
cutting toolsdiffusionoxidationabrasiondelaminationadheasionsurface
effectsvolume effectsstressesfracture formationoutbreakbreakPrimary
task of the hard material layer is to prevent the contact between
work material and tool during machining in order to reduce the tool
wear caused by adhesion, abrasion, diffusion and oxidation at the
surface of the cutting material. 37Seite 37 WZL/Fraunhofer
IPTDesign of a CVD coating
installationCHH2H2+TiCl4liquidTiCl4evaporatorgas exitcoating
furnacegas entranceH2To produce a TiC-layer for example
Titantetrachlorid??? (TiCl4) is vaporized and lettogether with
methane to a reaction vessel which can hold a couple of thousands
of cutting inserts. Thereby the titaniumcarbide is produced in a
chemical reaction at a temperature between 900 C and 1100 C and a
pressure below atmospheric pressure. 38Seite 38 WZL/Fraunhofer
IPTTTT-curve of a WC Co alloy at coating temperaturesWC Eta
Eta'Co3W200400600800100012000,01 0,1 1,0 10 100 1000temperatureT /
Ctime t / hCo - 5 W - 0,23
CHT-CVDMT-CVDP-CVDPVDTime-Temperature-Transformation chart of a
cobalt aloy. Listed are typical coatingtemperatures and times for
the processes HAT-CVD, MT-CVD, PA-CVD and PVD. The figure shows
that in the classical HT-CVD and middle temperature-CVD-process
thearea of eta-phase-precipitation is run through respectively
affected.Compared to that in low temperature processes like PA-CVD-
and PVD-processes no changes of constitution is to be expected.
39Seite 39 WZL/Fraunhofer IPTCoating process and flexural
strength14,52,6FPA-CVDPVDPVDCVDchangeof flexuralstrength/
%10100-10-20-30-40-50-600 2 4 6 8700C550C1000C400Ccoating thickness
/ mTiNTiN/Ti(C,N)PVDCVD PVDPVDPA-CVDThe comparing examination of
the bending strength of thin, differently coated WC-Co cemented
carbides shows which influence the coating temperature and layer
thicknesshave on this important paramater of toughness
performance.40Seite 40 WZL/Fraunhofer IPTCoating method and cutting
performance10000050000100005000100050010060 80 100 200 400
300impactsncutting speed vc/ (m/min)work mat.:42CrMo4+QTRm= 980
N/mm2substrate:P30/40SPUN 120312f = 0,2 mmap= 2,5
mmMT-CVDuncoatedArc-PVDThe MT-CVD- as well as the PVD-coated
cemented carbide are clearly superior in theirperformance compard
to the uncoated cemented carbide.Coming to lower cuttingspeeds the
PVD-layer shows advantages.41Seite 41 WZL/Fraunhofer IPTCommonly
used layer structuretypical multi-layer with functionalIntermediate
layersmultilayer (nano-structure)graded layermonolayer (thin hard
layer)t = 0.5 ... 50 mt = 0.5 ... 10 mt = few atomic cells ... 100
nmhard and soft compounds(MoS2, WC/C, graphite etc. .)hard film +
solid lubricantfilm(a-Me-C:H)super hard coatings(CVD-DP /
BN)42Seite 42 WZL/Fraunhofer IPTIncreased tool life using
Middle-Temperature-CVD-coatings43Seite 43 WZL/Fraunhofer
IPTPerformance of Plasma-CVD coated cemented carbidecarbide P25 /
TiN, PA-CVD - coateddisk millingwork material: 60WCrV8,220
HBcutting material: HW-P25vc= 80 m/minfz= 0,08 mmae= 42 mmap= 6 mm
type of coatingworktravellf/ mPA-CVD none HT-CVD0412168The
attributes of PA-CVD-coated cemented carbides have a positive
affect on theirperformance in machining higher-strength steel
workmaterials in interupted cut.The sensitivity of the composite
against Kammrissbildung ??? and failure throughdecomposotion is
much smaller compared to HAT-CVD-coated cutting materials.44Seite
44 WZL/Fraunhofer IPTImproved wear resistance and tenacity using
multilayer coatings010203040607080%1001 m / 9 m4 m / 6 m6 m / 4
mAlONTiNAlONTiNAlONTiNAlONTiN3 mprobability of tool breakagesingle
layer thickness Al2O3
/TiCPVDCVDPVDP-CVDCVDwearresistancetenacitycoating
thicknesstransientcoatingsubstrateCVD -coatingAl2O3 / TiCtotal
coating thickness for all tools 10 msource: Widia, SumitomoWith
rising coat thickness the wear resistance of CVD-coated cemented
carbidesincreases, at the same time however the bending strength
and therewith the toughnessdecreases.45Seite 45 WZL/Fraunhofer
IPTIncreased fracture resistance using graded subsurfaces360%P
251000 1200 1400 1600hardness HVmultilayercoating
ongradedsubsurface100%tool lifeworkpiece: C25vc=200 m/minf=0,15 -
0,3 mmap=0,5 - 1,5 mmgradedsubsurfacehardness10 mmultilayer
coating46Seite 46 WZL/Fraunhofer IPTImprovement of edge stability
using Ti(C,N)-transition layers47Seite 47 WZL/Fraunhofer
IPTCVDmultilayer-coatings with ZrSEM-picturecarbidecalotte
crater48Seite 48 WZL/Fraunhofer IPTC-based
coatingshydrogen-contenthardnesscrystal latticeof graphitecrystal
lattice of diamondclassification of C-based coatings basedon
hydrogen-content and hardnessdiamondgraphiteplasma-poymeramorphous
carbon(DLC)49Seite 49 WZL/Fraunhofer IPTCVD-diamond thin-film
coatingsmicro-crystalline (standard) nano-crystalline (even)
multi-layer (even)micro-crystallinenano-crystallinesource:
CemeCon50Seite 50 WZL/Fraunhofer IPTReduced adhesion and abrasion
by smooth CVD-diamond coating100 m5 m900 m900 mrake face900 m900
msevere adhesions900 msevere adhesionsflank facePVD-TiB2CVD-diamond
coated tool (coating thickness 4m)New lc= 40 m lc= 40 mvc= 200
m/minfz= 0,15 mm dry HC-K20 end mill with two teethd = 10 mmap= 3
mmslot milling51Seite 51 WZL/Fraunhofer IPTPhysical Vapour
Deposition (PVD) coatings ~500C instead of 1000C (CVD) limited
chemical bonding with substrate preservation of compressive
stresses during the substrate grinding process sharp edges
preservation of the toughness in the substrate material HS coatable
lower layer thicknesses compared to CVD52Seite 52 WZL/Fraunhofer
IPTPVD-process vacuum platinggas inletinert processgasreaction
gasvacuum plating device- electrical heatingor- electron beam
(EB-PVD)vacuum pumpenergy supplyevaporatorspecimen holder,bias
voltagewater cooledrecipientelectron beam (EB-PVD)target
materialmetal ionsplasmaandreaction gas ionscoatingBeim
Vakuumverdampfen wird das Schichtmaterial in einem Tiegel im
Hochvakuum verdampft. Die Dampfatome weisen bei diesen Drcken
mittlere freie Weglngen von bis zu mehreren Metern auf. Sie treten
deshalb i. Allg. nicht in Wechselwirkung miteinander und gelangen
geradlinig zum Substrat. Da dieses erheblich klter ist als der
Dampf, kondensieren die Teilchen auf dem Substrat. Aufgrund des
geradlinigen Teilchenflugs muss der Substratwerkstoff in der
Beschichtungskammer bewegt werden, um Abschattungseffekte und
ungleichmige Schichtdicken zu vermeiden. 53Seite 53 WZL/Fraunhofer
IPTPVD-process sputteringvacuum pumpadditionalmagnet systemsputter
device- without additionalmagnetic field:diode-sputter-source- with
additionalmagnetic field:magnetron-sputter-source1-5 kVelectrode as
additionalion source- +gas inletinert processgasreaction gasmetal
ionsplasmaandreaction gas ionscoatingspecimen holder,bias
voltageevaporatortarget materialIn einem Niederdruckplasma wird ein
Inertgas (z.B. Argon) durch Anlegen einer Hochspannung ionisiert.
Die positiv geladenen Inertgasionen werden auf das als Kathode
geschaltete Target (Schichtwerkstoff) hin beschleunigt und schlagen
dort durch Impulsaustausch Atome, Atomgruppen und Molekle des
Beschichtungsmaterials heraus.54Seite 54 WZL/Fraunhofer
IPTPVD-process Arc-ion platinggas inletinert processgasreaction
gasvacuum pumpmagnets for arc stabilizingresp. steering rotating
arcplasma channel105000 V - +bias voltagespecimen holdermetal
ionsplasmaandreaction gas ionscoatingBeim Ionenplattieren wird das
Substrat mit einer negativen Spannung, die sog. Biasspannung,
beaufschlagt. Der Metalldampf wird durch im Gasraum angeordnete
Elektroden und elektromagnetische Felder ionisiert. Ein Teil der
ionisierten Teilchen wird zum Substrat hin beschleunigt. 55Seite 55
WZL/Fraunhofer IPTExample for a coating machine56Seite 56
WZL/Fraunhofer IPTCoating prevents built-up edges0,2 mm0s005 9 0
35mPVD - TiN - coatedvC = 63 m/min broaching oil vC = 63 m/min
dryvC = 63 m/min dry vC = 63 m/min dryworkpiece material:17CrNiMo 6
BGtool material: WC 6 Corise per tooth:h - 0,1 mmcutting tool
geometrie:Becaue of the use of PVD-TiN- coated instead of uncoated
cemented carbides the built-up-edge formation is supressed in the
complete examined cutting speed area of vc= 10 63 m/min because of
the decreased adhesion between the chip and cutting material.
57Seite 57 WZL/Fraunhofer IPTPhysical and chemical properties of
coatings*data for the cubic NaCl-structure at 50% TiC/TiN or
TiN/AlNverygoodverygoodmean good mean chemical resistance8,0 9,4
7,7coefficient of thermal exspansion 25/1000/ 10-6/K-1675,7 -156,3*
-260,0* -337,6 -184,1enthalpy of forming H298K / kJ/mol23002400
-33002600 -34002300 3100micro hardness/ HV 0,05 -Al2O3(Ti,Al)N
Ti(C,N) TiN TiC58Seite 58 WZL/Fraunhofer IPTNotch Wear and
AbrasionHW-P10HC-P10(TiAlN)Dry Synthetic Ester
SubstrateSpalling100mNotch= 37 minVBN= 0,2 mmProcess:Turning
(external)Material:42CrMo4VInserts:HW-P10, HC-P10(SPUN
120304)Cutting parameter:vc= 150 m/minf = 0,12 mmap= 1,0
mmAbrasion= 69 min= 48 min = 23 min59Seite 59 WZL/Fraunhofer
IPTOxidation Resistant Coating Systemsester with
additivesoverviewwear of minor cutting edge600 m300
mVBNmax(Ti,Al)N/Al2O3tc= 57 minProcess:Ext. cyl.
turningMaterial:X5CrNi18-10Cutting material: :HC-K20(SPUN
120308)Cooling lubricant::Ester without add.Cutting parameters::vc=
150 m/minf= 0,12 mmap= 2,5 mm050100150200mWidthof wearland VB Nmax,
VB Nn(Ti,Hf,Cr)N (Ti,Al)N-Reference-VBNntc= 40 min tc= 57 min
VBNmaxVBNnVBNmax60Seite 60 WZL/Fraunhofer
IPTStructureIntroductionTool steelCemented carbideCoatings
Summary61Seite 61 WZL/Fraunhofer IPTQuestions Which are the main
components in high speed steel (HS), WC-Co-based cemented carbides
(HW) and cermets (HT)? Why are complex tools such as broaching and
gear hobbing mills often made of high speed steel (HS)! Why do
cermets (HT) have a higher thermal strength than WC-Co-based
cemented carbides (HW)? A given finishing turning process does not
deliver the required surface finish. The surface obtained is too
rough. What measures can be taken to increase the surface finish.
Cemented carbides from the P-group have high content of TiC, TaC
and NbC carbides, low content of WC. What is the benefit of this
composition, what are the disadvantages? What are the advantages of
CVD-coatings compared to PVD-coatings? A high speed steel has to be
coated. What type of process (CVD, PCD) do you consider. What wear
effects can be influenced by a coating? What are main failure
effects of coating?62Seite 62 WZL/Fraunhofer IPTQuestions How does
particle size in cemented carbides influence toughness What can be
done to overcome build up edges What are the main conditions to
promote adhesive wear What can be done to prevent adhesion Which
material more sensitive to adhesion (compare against tool steel):
Aluminum, carbon steel (0,6% C) or grey cast iron (GG 15) Show for
K - grade carbides the dependence of grit size and cobalt contend
on toughness Show for K - grade carbides the dependence of grit
size and cobalt contend on hardness