Ferro-Titanit®

Guidelines on Machining

Contents04 The material06 General information on machining08 The individual types of machining22 Product forms

Sintering furnace

02

03

Ferro-Titanit® is the trademark used by Deutsche Edelstahl-

werke GmbH for machinable and hardenable alloys produced

by powder metallurgy techniques. Materials that have so far

been available for tools and wearing parts have included tool

steel and tungsten carbide alloys. Ferro-Titanit® material

combines the properties of steel and tungsten carbide alloys.

It is possible to machine this material by conventional methods in

the asdelivered condition. When hardened (up to 69 HRC), Ferro-Titanit® can

be used to economically solve many wear problems. The advantages of powder

metallurgy compared with usual melting methods - no fibering, no segregation,

homogeneous fine-grained carbide distribution, no impurities, etc. - allow Ferro-

Titanit® to be alloyed with one of the hardest carbides (titanium carbide) by as

much as 45% by vol. without losing the machinability.

The material

Titanium carbides in steel matrix,scale approx. 1:2000

04

Advantages of Ferro-Titanit®

lowspecificweightof6.5g/cm3

machinable by sawing, milling, turning,

drilling,etc.

hardenableupto69HRCwithverylittle

distortion

changeindimensions<0.1%

frequent possibility of recycling by

annealing, machining and rehardening

good possibilities of combination with

tool steel due to favourable technological

properties

minimum pick-up with other materials

good damping properties

The composition of the machinable

Ferro-Titanit® alloys consists of approximately

45%byvol.titaniumcarbideand55%

byvol.ofasteelmatrixthatistailoredto

theintendedapplication.Thematrixcan

be pearlitic, or nickel-martensitic for

precipitation hardening grades, or also

austenitic(seetable).Thecarbidesare

embedded in the particular matrix (see

figureontheleft).

Ferro-Titanit® grades

Microstructural condition HardnessCarbide- after Servicealloyed annealing hardnessmaterials HRC annealed hardened HRC

C-Spezial 49 pearlite martensite 69

WFN 51 pearlite martensite+precipitations 69

S 51 pearlite martensite+precipitations 67

Nikro128 52 nickelmartensite nickelmartensite+precipitations 62

Nikro143 53 nickelmartensite nickelmartensite+precipitations 63

U 51 austenite austenite 51

Cromoni 52 austenite austenite+precipitations 54

05

Production steps: powder, pressed blank, sintered blank, machined sleeve of Ferro-Titanit®

General information on machining

Ferro-Titanit® material contains twice as

manycarbidesassteel(morethan45%by

vol.comparedwith28%byvol.).The

carbides are relatively uniform in their

shape and distribution over the

wholecross-section.Thetitaniumcarbides

which,withahardnessof3200HV,

predominate along with chromium

carbides, are considerably harder than

the carbides, for example in high-speed steels

(WC=2400,VC=2800,Mo2C=1500,

Cr3C2=1300,Fe3C=approx.1100HV).

Variousalloysareusedasbindersinthe

steel matrix of Ferro-Titanit®.Totallydifferent

microstructuralconstituents,ormodifications

with very dissimilar hardnesses,

suchas80to90HVforferrite,210HVfor

pearlite,180HVforaustenite,900HVfor

martensite,and900to1000HVfor

ledeburite, come about as a function of

thealloycontentsandtheheattreatment.

Machiningisperformedonlyinannealed

condition.

Adherence to the greatly reduced cutting

06

speeds, that are required in comparison with

steelmachining,isessential.

Finish-machininginoneoperation,i.e.with

fulldepthofcut,isanadvantageousmethod.

Except for the case of grinding machining

shouldnotbeconductedwithrinsingfluidsor

coolants.Machiningwithrinsingfluidsorcoolants

isnotallowedexceptinthecaseofgrinding.

07

The individual types of machining

Turning

It is possible to machine Ferro-Titanit®

using high-speed steel at low cutting

speeds.However,heavynotchandedge

wearoccurswhichleadstorapidtoolfailure.

For this reason, it is preferable to use

tungsten carbide with a supporting chamfered

edge(seeillustration).Forguidelinevalueson

turningoperations,pleaserefertotable.

An even lower cutting speed down to as little

as4m/minmaybenecessaryfordiameters

lessthan10mmandfortoughcarbide-alloyed

materials with a matrix of nickel martensite

(Ferro-Titanit®128,143)oraustenite

(Ferro-Titanit®UandCromoni).

Drilling

Carbide-alloyedmaterialswithasteel

matrix can be drilled in annealed condition

using tungsten carbide or highspeed steel

(seetable).Lubricationorcoolinghasto

be omitted, since detached carbides in

combinationwithfluidsandpastesactas

anabrasive.Drillingsareconvenientlyremoved

fromdrillholesbymeansofcompressedair.

If drilling is performed by hand, a constant

contactforcemustbeensured.Whendiameters

greaterthan10mmaredrilled,thecentreline

between cutting edges is shortened by point

thinning.Themaincuttingedgeshouldnot

be shortened by more than one-third in this

respect.Thefeedforceistherebyreduced

while, at the same time, the start of drilling is

madeeasier.

Turning guideline values

Drilling guideline values

Cutting edge geometry Tool Tooland cutting conditions Tungsten carbide High-speed steel K 10/K 20/M 10

Cutting edge geometry Tooland cutting conditions Tungsten carbide K 10 High-speed steel

Clearanceangle a 6° 6°

Rakeangle g -6to0°(+6°) -6to0°(+6°)

Inclination angle l -4° 0°

Cuttingedgeangle x 60to70° 60°

Cornerradius r 1.0mm 1.0mm

Cuttingdepth a ifpossible,over1mm ifpossible,over1mm

Feedrate s 0.02to0.1mm/rev 0.02to0.1mm/rev

Cuttingspeed v 5to18(20)m/min 3to9m/min

Feedrate s 0.05mm/rev

Cuttingspeed v 2to4m/min

Angle of twist l 15to20°(20to30°)

Point angle e 90to120°

Carbide-tippedtoolchamfered

for turning Ferro-Titanit®,

conformingtoDIN4971(ISO1)

08

Planing guideline values

Milling guideline values

Cutting edge geometry Tool Tooland cutting conditions Tungsten carbide K 20 High-speed steel

Cutting edge geometry Tool Tooland cutting conditions Tungsten carbide High-speed steel K 10/K 20

Clearanceangle a 8° 8°

Rakeangle g 0° 0°

Inclination angle l -8to0° 0°(-5°)

Point angle e 120° 120°

Cuttingedgeangle x 45° 45°

Cornerradius r 1.0mm 1.0mm

Cuttingdepth a ifpossible,over1mm ifpossible,over1mm

Feedrate s 0.2mm/doublestroke 0.2mm/doublestroke

Cuttingspeed v 8to12m/min 6to8m/min

Clearanceangle a 8to10°

Rakeangle g 0to+8°

Edgeradius r 0.5mm

Cuttingdepth a ifpossible,over1mm ifpossible,over1mm

Feedrate s 0.1to0.2mm/tooth 0.1to0.15mm/tooth

Cuttingspeed v 6to15m/min 2to6m/min

Milling

Millingismostlymoreeconomicalthan

planing.Althoughthesurfacesproduced

by down-milling are rougher than those

produced by up-milling, down-milling is

recommended for Ferro-Titanit®.Up-milling

quicklybluntsthetool.Indown-milling,

the workpiece and tool have the same

directionofmovement.Spiral-flutedendmilling

cutters(15to25°)haveprovensuitablein

vertical milling machines, while face milling

cutters are preferable when working on

horizontalmillingmachines.Bothhigh-speed

steel and tungsten carbide tools can be used

foreithertypeofmilling.

Tungsten carbide tools allow higher cutting

speeds and result in longer cutting

distanceswithoutfailure.

For guideline values on milling work,

pleaserefertotable.

In slot milling and end milling, the sharp

edgesonthefacesmustberoundedoff.

Planing (slotting)

As already mentioned, milling is mainly

more economical than planing, which is

why the latter machining method is used

less.Inexceptionalcases,theshapeof

the tool being manufactured makes planing

indispensable.Animportantaspect

during planing is that the machining tool

lifts off on the return stroke, as otherwise

the tip of the cutting edge is easily damaged,

resulting in a poor surface and a high rate

oftoolwear.

Ifthispreconditionisfulfilled,however,

a superior-quality surface is mostly

producedincomparisontomilling.

For guideline values on planing,

pleaserefertotable.

In case of rollers and roller face cutters made ofHSS,thetypesnormallyusedforsteel-workingcanbeemployed.Spiral-flutedmillingcuttershaveprovenwellsuitable.

09

Countersinking

The cutting edge geometry and cutting

conditions for the countersinking of

Ferro-Titanit® are the same as for drilling

withHSSortungstencarbide.

Reaming

Reamingwithsmallmachiningallowances

isdifficultandleadstoimperfectsurfaces.

Topeeloutthefinecarbides,anallowance

ofaround0.25mmonthediameter

isadvisable.Theabradedmaterialmust

beremovedwithcompressedair.Cutting

speed:HSS3-5m/min,tungstencarbide

6-8m/min.

Band sawing

The sawing of Ferro-Titanit® requires

blades with a coarser pitch and a lower

cutting speed than are normally used for

steel.Thesawbladesmustbeset,as

otherwisethetoothflanksbluntquickly

andthebladesbecomestuck.Thecontact

pressure applied during sawing should

be greater than for steel and should not be

allowedtodecreaseduringcutting.The

numberofteethis3perinch.Thin-walled

partsrequire8-10teethperinch.The

cuttingspeedis5to10m/min.Band

sawbladeswitha2%tungstenalloy

content are equally as economical as

thosemadefromhigh-speedsteel.

Sawing of Ferro-Titanit®

10

Tapping

Tapped holes should be forgone if the

carbide-alloyed material workpieces are

tobesubjectedtohighlevelsofstress.

The acute threads can be starting points

forstresscrackingandfatiguefractures.

Athreaddepthof1.5xDissufficientfor

fasteningpurposes.Overlongthreadsonly

increasethetoolcosts.Femalethreads

smallerthanM6canbeproducedonlyby

carefully keeping to all the appropriate

guidelines.Suchsmallthreadsshouldbe

avoided,especiallyinblindholes.Whatever

the circumstances, the guidelines given

below should be followed:

Where possible, through-going threads

should be provided; for blind-hole

threads, an adequately deep drillhole

mustbeselected.

The core hole diameter should be 3 to

5%largerthanforsteelworkpieces.

Examples:

-uptoM5thread

corediameter1/10mmlarger

-greaterthanM5thread,uptoM10

corediameter2/10mmlarger

- for larger threads

M12x1drillholediameter11.1mm

M14x1drillholediameter13.0mm

Thetapisturnedslowlyforwards.

Beforeandwhilethetapisturnedback,

the drillings must be removed by blowing

outwithcompressedair.Giventheir

grainy form, they very easily become

stuck between the tool and thread, with

the result that the cutting edges run the

riskofchipping.

If the tap becomes hot to the touch, the

operation must be discontinued immediately,

as the steel tap will jam in place

as a result of its greater expansion compared

with the carbide-alloyed material

andmaybecomedamaged.

So-called“thread-cuttingstrands”have

proven particularly advantageous for

tappinginblindholes.Thestearin-like

strands, which are available for any diameter,

act as lubricants and convey the

abradedmaterialtothesurface.

Liquidlubricantsarenotrecommendable

since they cause the drillings to

stick together and the thread to consequently

become chipped when the tap

isturnedbackwards.

Recognisedthreadtapmanufacturers

supply special tools for Ferro-Titanit®

which are characterised by an extensive

“undercut”,awidechipchannelanda

rakeangleof0°.Inmanycases,itissufficient

to work with only one bottoming tap

whose cutting-face rake angle has been

reducedbygrinding.

11

Turning of a round bar of Ferro-Titanit®

Ondrillingmachines,threadsarecut

directly after drilling, without changing

thechuckingdevice.Thetapwithcentre

pin is inserted into the drill spindle in

placeofthetwistdrill.Thetapertapis

used for the in-line starting cut or

roughing out of the thread, and for this

reason,hasacentrepin.Whenthreads

are cut in through-holes, the operation is

performedwithoutaplugtap.Aplugtap

is required only for threads in blind holes,

to fully rough out the depth of thread

reducedbythetapertapcentrepin.

The bottoming tap renders the thread true

togauge.Ifhandtapsareusedwhose

cutting geometry and type are tailored to

Ferro-Titanit®, it is necessary to also heed

the following working conditions:

coreholediametertoDIN336,seriesII

(corresponding to the diameter of the centre

pinonthetapertap).Atthetimeofordering,

it must be indicated that the taps are

intended for Ferro-Titanit®.Ifthreadsareto

becutonlathes,pitcheslessthan0.5mm

arenotrecommendable.

12

13

Grinding

The high carbide content and the titanium

carbide‘s high hardness make it self-evident

that special attention must be paid when

grinding.Inwhichrespect,itisofdecisive

importance whether the carbides are present

in a soft-annealed or in a hardened steel binder

phase.Grindinginhardenedstateleads

tosignificantlyhighergrindingwheelwear.

For guideline values on grinding, please refer

totable.

If possible, Ferro-Titanit® should be extensively

preground in unhardened condition, in which

respectanallowanceof0.02-0.08mmper

sideissufficient.

This permits economical grinding after

hardening, as the dimensional changes

duringheattreatmentareextremelysmall.

Corundumwheelswithaceramicbond

and porous structure have proven a

suitablemedium.Diamondwheelsmade

from plastic-bonded, nickel-coated synthetic

diamonds with a concentration of

75c-100cinadiamondgritsizeof

D107-D151arerecommended

particularlyforthefinish-grindingof

Ferro-Titanit®inhardenedstate.

Attention must be paid to the following

basic rules when grinding:

Grind with a powerful, rinsing stream of

coolant directed as close as possible to

thewheel/workpiececontactpoint.

Selectthesmallestpossiblein-feedrate.

Grinding guideline values

Surface grinding

Cylindrical grinding

Internal cylindrical grinding

Cuttingspeedofthewheel vc 20to30m/sec

Feed rate vft 10to25m/min

Transverse in-feed ap 1/4mm/strokeofwheelwidth

In-feed ae 0.01mm/stroke

Cuttingspeedofthewheel vc 20to30m/sec

Table velocity vfa 1to2m/min

Workpiece circumferential velocity vw 10to20m/min

In-feed ae 0.01mm/stroke

Cuttingspeed vc 20to25m/sec

Table velocity vfa 1to2m/min

Workpiece circumferential velocity vw 15to20m/min

Workpiece feed rate ae 0.01mm/stroke

14

Grinding with diamond wheels

To gain maximum performance from carbide-

alloyed materials, grinding with diamond

wheels-chieflymadefromsynthetic,

reinforced diamonds in a plastic binder - is

recommended.Thefollowingadvantages

are derived compared with natural diamonds:

Betteradherenceofthereinforced

diamondstothebinder.

Higherthermalconductionthroughthe

metalreinforcement.

Greater material removal rate due to the

irregular crystalline structure of the synthetic

diamonds.

In the course of diamond grinding, the titanium

carbides are both peeled off and ground by

thediamondtips.Toquicklyandcompletely

remove the material abraded from the diamonds,

as well as the particles ground from the binder

and workpiece, it is necessary to operate

with a powerful, possibly double, jet of rinsing

fluidand/orcoolant.Thisapplieschieflywhen

grinding larger surface areas involving a high

volumeofmachining.Coolantscontaining

ahighamountofoilmustbeavoided.

Purewaterdissipatesheatfivetimesbetter

thanoil.Whengrindingwithdiamondwheels,

an adequate in-feed must be ensured so that

the wheel can constantly work out and does

notslideovertheworkpiece.Manyadditional

factors besides absolute roundness and

correct dressing of the wheel are essential

foreconomicalgrinding.Forthisreason,

there should be no hesitation to make use of

the technical advisory services provided by

experienceddiamondwheelmanufacturers.

All leading diamond wheel manufacturers

supply wheels for the machining of hardened

Ferro-Titanit®.WheelsmadeofBorazoncan

alsobeused,inplaceofdiamondwheels.

15

1 2

Surface grinding

Vibrations,whenthewheelcomesintocontact

with the workpiece, should be kept to a minimum

by using stable grinding machines with very

littlebearingclearance.Thisalsoincludesthe

reversing movement of the table taking place at

areasonabledistance.Thevaluea=0.4xDmm

(diameter of the grinding wheel) has proven

useful as the average interval for the start-up

andoverrunpositionsofthegrindingwheel.

It is possible to work with coolants on all surface

grindingmachines.Wetgrindingshouldtherefore

be selected, especially for carbidealloyed

materials.HardenedFerro-Titanit® should be

handledwiththesmallestallowancepossible.

Cylindrical grinding

Wheel compositions similar to those used

for surface grinding are recommended for

cylindricalgrindinginannealedcondition.

Here,too,theruleappliesthatonlypreferably

small allowances should be given before

hardening.Smalldiameterswithgreater

lengths can easily distort during heat treatment

so that, occasionally, a bigger allowance

maybenecessary.Thesurfacequality

required for a long tool life therefore has to

be achieved by subsequent lapping of the

outside diameter with a diamond paste and

bydiamondgrindingonthetop(e.g.fora

piercingmandrel).

16

1) Milling of Ferro-Titanit®

2) Turning of a composite-sintered part made of steel and Ferro-Titanit®

3) CNC machining of a composite part

3

Internal cylindrical grinding

Borazongrindstoneshaveprovensuitable

fortheinternalgrindingofdrillholes.

Normal grindstones can be used for

rough-grinding if diamonds are used for

finish-grindingafterthehardeningtreatment.

According to operating experience, it is

possibletoachievea30-50%savingin

machiningtimewhenusingBorazon

grindstones, compared with carbon

compounds.

17

Turning of a Ferro-Titanit® ring

Lapping (polishing)

Lappingisamethodbywhichsurfacesof

a high quality and great geometrical accuracy,

as well as precise compliance with the closest

tolerances,arepossible.Itisalsopartlysuitable

foreliminatingstructuraldeficienciesleftby

previousoperations.Wherecarbide-alloyed

materials in particular are concerned, the quality

of the surface is instrumentally important, just

as much for the life of the tools and machine

components as for the precision of the parts

thataretobemanufactured.Toreducelapping

to a minimum, it is necessary to pre-grind with

adiamondwheel.Thewheelsusedcomprise

synthetic, reinforced diamonds in a plastic binder

withadiamondgritsizeofD120toD70,

depending on the surface roughness and surface

zone.Ifdiamondwheelswithdifferinggritsizes

are employed, grinding must be performed

inalternatingdirections.

Thisisthenfollowedbylapping.Onelapping

toolmaybeusedonlyforacertaingrainsize.

In case of machine-lapping, a lapping paste

is applied to the workpiece, while for manual

lappingitisappliedtothelappingtool.This

should be commenced with a minimum of

diamond paste and light pressure on the lapping

tool.Thepastewilldarkenincolourandthicken

duetotheabrasion.Asolventsuitedtothe

diamond paste, as well as fresh paste itself,

must now possibly be added in order to re-

increasethepolishingefficiency.Rough-polishing

isperformedwithdiamondgritD15,and

finish-polishingwithD3.Ifnecessary,afollow-up

polishwithgritsizeD1ispossible.Polishingis

carried out using hardwood or hard felt wheels

18

that are obtainable from the diamond product

manufacturers.Givenbelowareafewtips

that deserve particular attention:

Beforelappingiscommenced,andbetween

eachoperationwithdifferentgritsizes,itis

necessary to thoroughly clean the surfaces

byrinsingwithbenzene,orsimilargrease-free

cleaner‘ssolvents,andwithcottonwadding.

If each piece of advice is followed, and the

pre-grinding and subsequent lapping of the

workpiece are performed well, a scratch-free

polish will come about after approximately

10minutesoveranareaof2cm2 of hardened

Ferro-Titanit® in which the carbides lie freely

exposedatthesurface.

This should be the aim of any polishing!

When the titanium carbides lie freely exposed,

they can exert their resistance to wear and

pick-up.Ifasurfaceispoorlylapped,the

carbides only remain in the background because

theyhavebeensmearedoverbythesteelmatrix.

The reason for this is that polishing has not

been carried out for long enough, or that too

finealappingabrasivehasbeenused.Silicon

carbide and boron carbide are similarly less

suitable for the lapping and polishing of hardened

Ferro-Titanit®.

Undesirable pores develop during pregrinding,

e.g.whenusingcorundumwheels.Forthis

reason, attention is drawn again to the fact that

especially diamond grinding is very important

beforepolishing.Because,onlyadiamond

can cleanly cut the hard titanium carbides and

thus create the precondition for a closed

surfacestructure.

19

Charging of knife bars

The polishing of a wrongly ground surface

can take hours, as a high amount of material

hastoberemoved.Whenthegrainsizeis

changed, the diamond grain becomes stuck

in the pores and repeatedly causes grooving

(“curves”,“shootingstars”).Agoodpolishis

recognisable by extremely little roughness

(lessthan1μm)andalsobytheso-called

“dull”lustre,i.e.thesurfacesappeara

milkymatt-bluishcolour.Thisappearanceis

due to the minor differences in height between

carbideandalloymatrix.Ifcarbide-alloyed

materials are poorly polished, the surface

always has a bright, clear lustre, comparable

toametalorcrystalmirror.

These characteristics are of special importance

forpracticians.Particularattentionmustbe

paidwhenlappingonbuffersorlathes.The

circumferential velocity of the part undergoing

polishingshouldbe10to12m/min.Athigh

speeds and pressures, it is possible for carbides

to also be torn out by diamond abrasives and

for the surface to become smeared over with

alloymatrixmaterial.

Finishing after hardening

Any of the spark erosion and electrochemical

abradingprocessescanbeusedforthefinishing

of Ferro-Titanit®(primarilyinhardenedcondition).

It is, however, essential to bear in mind that

Ferro-Titanit®, in the same way as high-speed

steel, for example, consists of different

20

Internal turning of a sleeve

components (matrix - carbides) and that these

alsoreactdifferently.Thesteelmatrix,for

instance, reacts much more strongly than

carbides,inspiteofdifferentiablecomposition.

The structure is strongly fragmented, from which

thecarbidesareabletobreakout.Itthusfollows,

and has been proven many times in practice,

thatfinishingisalwaysnecessaryaftermachining

by means of the mentioned processes if maximum

performance is to be obtained from Ferro-Titanit®

orothermaterials.

21

Product forms

The machinable and hardenable Ferro-Titanit®

gradesaresuppliedmainlyassemi-finished

material in soft-annealed condition, with

a machining allowance of approximately

0.5to1.0mmontheordereddimensions.

Typical product forms include

disks and cylinders

ground round bars

rings and sleeves

square dimensions

inturnedormilledexecution(finished

partsuponrequest).

Any tool shop therefore has the possibility

to machine tools and other wear-exposed

parts, as opposed to tungsten carbide

materials, on equipment normally used for

machiningsteels.

Basically,partsmadeofhardenablecarbide-

alloyed material are rough-machined as far as

possible in the annealed, assupplied condition

and are then hardened, preferably in a vacuum

furnace,aswellastempered.Ferro-Titanit®

can be hardened with little distortion, the

changeindimensionsbeinglessthan0.1%

oftheas-supplieddimensions.

Ferro-Titanit® can be joined permanently to

22

steelbyspecialmethods.Thispossibility

can be used to apply the material only

toparticularlyexposedareas.

General note (liability)

Statementsastotheconstitutionorutilisation

of materials or products are for the purpose

ofdescriptiononly.Anyguaranteesinrespectof

the existence of certain properties or a particular

application require special written agreement

atalltimes.

23

DEUTSCHEEDELSTAHLWERKEGMBH

Oberschlesienstr.1647807Krefeld,Germanysales@ferro-titanit.comwww.dew-stahl.comwww.ferro-titanit.com