Hermes Superabrasives - Hermes Schleifkörper GmbH

Bonded Abrasives
Hermes Superabrasives
CBNandDiamond
vitrifiedbondedabrasives
C on t en t s
Hermes Abrasives Group
TheHermesAbrasivesGroup........... 4
HermesSchleifkörperGmbH........... 5
Quality–ourtrademark............. 5
Fornatureandtheenvironment.......... 5
Abrasives
Diamond ................... 6
CBN(CubicBoronNitride)............ 7
Thebenefitsofvitrifiedbonded
CBNandDiamondgrindingwheels......... 6
Primaryapplicationsforvitrifiedbonded
CBNandDiamondgrindingwheels......... 7
Hermes solutions
Internalcylindricalgrinding ............ 8
Surfacegriding................ 9
Externalcylindricalgrinding............ 10
Rollgrinding................. 12
The first step to success
Yourinformationsforus ............. 13
Hermes Superabrasives
identification system
Shapesanddimensions............. 14
Specification ................. 16
Application recommendations
Process-andtoolparameter ........... 20
Machineparameter ............... 21
Coolinglubricants ............... 22
Dressingmethods ............... 23
Keydatainthegrindingprocess.......... 25
Internet
Whynotvisitourwebsite–
www.hermes-schleifkoerper.de.......... 26
H er m es A br asives G r oup
The Hermes Abrasives Group
TheHermesparentfactorywasfoundedintheLurupdistrictofHamburgin1927and
hasremainedthegroup‘sheadofficetothisday.
Hermesnowhasover11productionfacilitiesandsubsidiariesin4continentsthroughouttheworldandfordecades,hasbeenaworldmarketleaderintheproductionof
abrasives.
Themapoftheworldbelowillustratesourpresenceandourcommitment.
Dr. Siegfried Blankenburg
ManagingDirector,
HermesSchleifkörperGmbH,Dresden
DearHermesCustomers,
Iamdelightedtotaketheopportunity
presentedbythepublicationofour
“HermesSuperabrasives–CBNand
Diamondvitrifiedbondedabrasives”
brochuretothankallourfriendsand
businesspartnersverymuchfortheir
loyaltytothecompany.
Iwouldliketoassureyouthatwewill
continuetodoeverythingwecanto
satisfyyourrequirementsinfullby
developingandmanufacturingquality
products.
Youmayassumethatourtoppriority
isalwaystohavesatisfiedcustomers.
Eachdaywestartafresh,doingeverythinginourpowertoachievethis.
Headquarter Germany
Hermes Austria
Hermes USA
Hermes China
Hermes France
Hermes Great Britain
Hermes Germany
Hermes Poland
Withbestwishesforourcontinued
partnershipinaspiritofcooperation,
Bestwishes
Hermes Romania
Hermes China
Dr.SiegfriedBlankenburg
Hermes Singapore
Hermes Canada
Hermes USA
Hermes Austria
Hermes Bulgaria
Hermes Schleifkörper GmbH
Quality – our trademark
Ontheonehand,weoweagreatdealtotradition,butonthe
other,wearepioneersinthedevelopmentofinnovativeproducts;
Hermesplacesenormousvalueontheproductionofhigh-quality
abrasivestothelateststateoftheart.
Hermesvitrifiedbondedsuperabrasivesareoneoftheoutstanding
productstrengthsoftheHermesAbrasivesGroupanditsworldwideoperations.
Thebondedabrasivesactivitiesofthegrouparebundledin
Hermes Schleifkörper GmbHinDresden,withtwoproduction
facilitieslocatedinDresdenandinUetersen,nearHamburg.
Inbothplantsareworkingover160employees.Thismeansthat
HermesSchleifkörperGmbHisthethirdlargestmanufacturerof
bondedabrasivesinGermany.
Since1986,CBNandDiamondbondedabrasiveshavecomplementedtheinnovativerangeofprecisionceramicandresinbonded
abrasives,honingringsandPUR-bondedpolishingabrasives.
Tomaintainandexpandthishighqualitystandardinfuture,the
TÜVCERTtestingbodyhasawardedtheHermesGroupthequality
sealforsatisfyingtherequirementsofDINENISO9001andthus
confirmedit.
Hermesisafounder-memberoftheOrganisationfortheSafety
ofAbrasives–oSa,themembersofwhichhaveundertakento
manufactureandsellsafebondedabrasiveswhichprevent
accidents.HermesSuperabrasivesaccordinglysatisfyallthe
safetyrequirementsofDINEN13236andalltheprecisionrequirementsofDINISO22917.
Ourcustomers–inotherwordsyou–derivegreatbenefitfrom
thissecurity.
For nature and the environment
Compliancewithnationalandinternationallawsandregulations
isoneofthemostimportantprinciplesofHermes‘environmental
policy.
The“Environmentalprotection”departmentatHermestakes
painstakingcaretoensurethateverybusinessprocesssaves
naturalresources.Thismakesprotectionoftheenvironmenta
cornerstoneofHermes‘commercialpolicyandakeycomponent
ofourcorporateresponsibility.
A br asives
Diamond
Diamondhasthegreatesthardnessandresistancetowearofallknown
substancesandisthereforesuitableformachining(grinding)hardandbrittle
materialssuchashardenedmetal,cermets,glassandceramic.Syntheticallyproduceddiamondismainlyusedforabrasivesnowadays.
Thestartingmaterialiscarbon(graphite)which,undertheeffectsoftemperature,
pressureandcatalysts,issynthesizedintothediamondcrystallattice.Diamond
hasahighaffinityforcarbon,i.e.carbon-containingmaterialsuchassteeldraws
carbonoutofthediamondundertheactionofheat,destroyingthecrystalline
structureofthediamondintheprocess.Diamondisthereforesuitableonlyin
specialcases,ifatall,fortheeconomicgrindingofsteelsandgreycastiron.
Carbon atom
Material properties
Hardness
10ontheMohsscale
Thermal
conductivity
thehighestofall
substancesatroom
temperature
Coefficientoffriction
extremelylow
Chemical
resistance
toacidsandbases
upto800°C
Density
3.51g/cm³
Chemicalsymbol
C
Unitofweight
carat(1carat=0.2g)
Crystal morphology
Thepossibleshapes(morphology)ofsyntheticdiamondcrystalsextendfrom
thecubetotheoctahedron.
Octahedron
Cube
The benefits of vitrified bonded
CBN and Diamond grinding wheels
Incontrasttootherbondsystems,itispossibletodressvitrified
bondedgrindingwheels(resetthebond)without subsequent
sharpeningwhichiswhythedressing process can be both
reproducedandautomated.
Intheproductionofthesebondedabrasives,theporosityof
thismaterialcanbesetfromclosedtoveryopen.Amongother
features,theoptimizedporosityofvitrifiedbondedCBNand
Diamondgrindingwheelsmeansthattheyalsogeneratecool
grindingbecausetheporesguidethecoolinglubricanttothe
pointofgrindingandtransportthechipswhichformawayfrom
thecontactzone.
Specificadjustmentofthevolumetricratiobetweenabrasiveand
poresallowsgrinding forces to be kept lowandhigher performance parameters to be achieved in the grinding process.
6
Theuseofmaterialswhicharedifficulttomachineandwhich
cannotbegroundeconomicallyusingconventionalabrasiveshas
increasedsignificantlyinrecentyears.
Moreandmoresteelsproducedbythepowdermetallurgymethod
arebeingused,forexampleandthesearegroundwithvitrified
bondedCBNgrindingwheels;theuseofhardenedmetalsand
oxideceramicsisalsoincreasingandconsequentlysoistheuse
ofvitrifiedbondedDiamondgrindingwheels.
CBN (Cubic Boron Nitride)
CBN(CubicBoronNitride)hasthesamecrystallinestructureasdiamondandis
thereforelikewiseextremelyhard.InCBN,boronandnitrogenatoms,ratherthan
carbonatoms,formthecrystallattice.
Cubicboronnitridedoesnotoccurinnatureandisthereforeproducedonly
syntheticallyinasimilarprocesstothatforsyntheticdiamond.In1957,
GeneralElectricwasthefirstcompanytosynthesizeCBN.
BecauseCBN,incontrasttodiamond,isfreeofcarbon,itisparticularlysuitable
forgrindinghardenedsteelscontainingcarbon.
Material properties
Hardness
9.5ontheMohsscale
Thermal
conductivity
high
Coefficientoffriction
low
Chemical
resistance
veryhigh
Density
3.48g/cm³
ChemischeElemente
B(Boron),N(Nitrogen)
Unitofweight
carat(1carat=0.2g)
Boron atom
Nitrogen atom
Crystal morphology
ItsmorecomplexatomicstructuremeansthatCBNhasmorecrystalshapes.
Inadditiontotheshapesbetweencubesandoctahedronsalreadyknown
fromdiamond,CBNhasothercrystalmorphologiesbetweenoctahedraand
tetrahedra.
Cube
Octahedron
Tetrahedron
Primary applications for vitrified bonded
CBN and Diamond grinding wheels
CBN
Diamond
• Iron/carbonmaterialswithahighproportionofalloywhichare
hardtomachine,especiallysteel;hardnessprimarily>55HRC
• Hard,brittle,short-chippingmaterialswhichdonotcontainiron
• High-speedsteel(HSS),caststeel,rollingbearingsteel,grey
castiron,stainlesssteels,temperedcastiron,heat-resistant
steels,steelsproducedbythepowdermetallurgymethod
• Hardenedmetal,glass,ceramic,quartz,semiconductor
materials,plastics,glassfibre-reinforcedplastics,natural
stone,concrete,compositematerialsandplasticingeneral
7
H er m es s olu t ions u sing CBN bonded abr asives
Internal cylindrical grinding
Product description
HermesCBNvitrifiedbondedabrasivesforinternalcylindrical
grindinghaveprovedoutstandinginmediumtolarge-scale
production.
Inthecourseofintensiveresearchwork,wehavedeveloped
anextraordinarilysharp,high-performancebondforinternal
cylindricalgrinding.
Thisbondenablesourbondedabrasivestoachievelongertool
lifes(chipvolume)anditsexcellentself-sharpeningproperties
reducegrindingtimes.
Bondedabrasivescanalsobesuppliedwithasteelorhardened
metalshaft.Hermesofferscustomersanadditionalserviceof
gluingbondedabrasivestoshaftsprovidedbythecustomer
(e.g.whenabrasivecoatingsareworn).
Product benefits
Applications
Hermes solutions for bores
• Considerablyreduceddressingtimes
Specification
20B 76 M-N4-5 V24 200
Operating speed
63m/s
Dimensional example
1A1W40x55x16-X5
Material
16MnCr5
Applications:
• Automotiveandautomotivesupplierindustry
(e.g.rockers,valvebodies)
• Transmissionengineering
(e.g.boresforgearwheels,guiderings)
• Electricalindustry
• Longtoollifesmeansreducedtoolcosts
Hermes solutions for rolling bearing races (outer rings)
Specification
Material
28B 64 X4 V31K 240
100Cr6
Hermes solutions for bore bushes
Specification
Material
8
20B 46 P3 V24 175
100Cr6
• Shortergrindingtimesincreaseproductivity
Comparison of performance, vitrified bonds
130%
120%
110%
Tool life
Specification
12B 64 X4 V31K 240
Operating speed
63m/s
Dimensional example
1A87x12x4.5
Material
16MnCr5
Applications:
• Rollingbearingindustry
• Mechanicalengineering
(e.g.boresforhydraulicparts,nozzles,bushes)
• Verygoodsurfacequalities
100%
90%
80%
70%
60%
50%
Reference
V31
at conc. > 200
V24
at conc. <_ 200
Surface grinding
Product description
Hermessurfacegrindingwheelsarecharacterizedbytheideal
balancebetweenthethreemaincomponents:abrasive,poresand
ceramicbond.
Thisfacilitatescoolgrinding,highrelativemetalremovalratesand
outstandingtoollifes.
Hermessurfacegrindingwheelsarevitrifiedbonded,socanbe
dressed.Theycanbeusedforabroadrangeofmaterialsrequiring
machining.
CBNbondedabrasivesforhigh-performancesurfacegrindingfrom
80m/soperatingspeedareavailablewithmetalcorebodies.
Product benefits
Applications
Hermes solutions for reciprocating grinding
• Preventthermaloverloadoftheworkpiece
Specification
Material
• Flexiblewithregardtothematerialforgrinding
23B 126 N6 V24 125
16MnCr5
• Saveretoolingtime
Hermes solutions for creep feed grinding
• Highdegreeofprofilestability
Specification
Material
• Increasedproductivity
23B 91 N6 V24 100
X155CrVmo12-1
• Longtoollifes
• Reducedworkpiececosts
9
H er m es s olu t ions u sing CBN bonded abr asives
External cylindrical grinding using Quickpoint method
Product description
SegmentedHermesSuperabrasivesforpeelgrindingallow
operatingspeedsofupto140m/s.
Theiroutstandinggrindingpropertieswereachievedbya
newly-developed,vitrifiedbondmatrixinconjunctionwith
specially-selectedCBNgritqualities.
ThetoolsareusedonJunker‘sQuickpointmachines,
forexample.
Hermes solutions for das Hochleistungs-Schälschleifen
Product benefits
Specification
Operating speed
Dimensional example
Material
Workpiece
23B 126 R4 V241 161
125m/s
3A1400/J297.5x25x127-U8-X5
temperingsteel,sinteredmetal
camshaft
Specification
Operating speed
Dimensional example
Material
Workpiece
10B 126 T3 V42 161
125m/s
3A1406/J342x18x127-U6-X8
temperingsteel
camshaft
Applications
Productivity comparison
Diagram illustrating
the principle of peel
grinding
%
140
Directionofgrinding
120
100
80
Surface
grinding
60
Grinding
radii
External
cylindrical
grinding
40
20
0
Standard bond
V241
Grindingproovesandinfeeds
• Longtoollifes
• Automotiveandautomotivesupplierindustry
• Considerablyreduceddressingtimes
• Cuttingtoolindustry
• Lowwearongrindingwheels
• Transmissionengineering
• Increasedproductivity
• Machinetoolengineering
• Verygoodsurfacequalities
• Textilemachineengineering
• Printingpressengineering
• Electricalindustry
10
External cylindrical grinding of crankshafts
Product description
HermescrankshaftgrindingwheelswithsegmentedCBNcoatings
canbemanufacturedinexternaldiametersupto750mm.
Furtheroptimizationofhigh-performancebondV24hassignificantlyimprovedgrindingproperties.Thesignificantlyincreased
profilestabilityoftheCBNcoatinginparticularleadstoshorter
grindingtimesandlongertoollifes.
HermesSuperabrasivesforexternalcylindricalinfeedgrindingcan
beusedatoperatingspeedsofupto160m/s.
Hermes solutions
Specification
Operating speed
Dimensional example
Material
30B 126/181 R6/T6 V04 150/125
Sandwichdesign
125m/s
1L1-450x24x127-U21-R1.8-X5
temperedsteel
Specification
Operating speed
Dimensional example
Material
23B 151 N7 V241 161
125m/s
3A1-600/J275x40x140-U20-X8.5
temperedsteel(e.g.16MnCr5)
Product benefits
• Preventthermaloverloadsontheworkpiecedespite
extremelyhighmetalremovalrate
• Saveretoolingtime
• Highdegreeofprofilestability
• Longtoollifes
• Increasedproductivityfromreducedworkpiececosts
Applications
• Grindingpinsandjournalsoncrankshafts
Also:
• Grindingbearingseatsontransmissionshafts
• Otherexternalcylindricalinfeedgrindingprocesseswith
extremelyhighRequirementswithregardtoreducedgrinding
timewithtightestadherencetosurfaceanddimensional
tolerancesontheworkpiece
External cylindrical grinding of pump cams
Grinding process
Workpiece
Operating speed
Material
Hermes solutions
pumpcamsoncamshafts
125m/s
16MnCr5(1.7131),58HRC
Specification
Dimensional example
23B 126 M7/6 V241 125
Form14A1
400/J192x27x127-U25-X5
11
H er m es s olu t ions u sing CBN bonded abr asives
Roll grinding
Product description
High-alloymaterialsrequiresuitablehigh-performanceabrasives
forrollgrinding.
Ournewly-developedCBNgritmixturemeetsthisneed.The
performancepotentialofCBNrequiredisexploitedtothefullin
combinationwithahigh-performancebond.
Hermes solutions for high-performance peel grinding
Specification
Operating speed
Dimensional example
Material
73B 107 P7/6 V04 100
50m/s
1A1-600x40x203.2-X3
e.g.ASP2023
Product benefits
• Surfacesarestableinthelongterm,yetcanhavevarying
designs(adjustablebymeansoftheappropriatedressingand
grindingparameters)
• Saveretoolingtime
• Generatesurfaceswithouttwistsorpatterns
• Longtoollifes
• Increasedproductivity
Applications
• Workingandback-uprollersincold-rollingapplications
• HighlysuitableforservicingSendzimirstands
• Grindinghigh-alloy,wear-resistantsteels,e.g.high-speedtool
steelwith12%Cr(e.g.1.2379)andhigh-performancehighspeedsteelproducedbythepowdermetallurgyprocess
(ASP2023)
12
T he f ir s t s t ep t o su c c es s
Your information for us.
Note
Your process data and optimization objectives form the basis for us applying our expertise and thus for our shared success.
Please fax the form to +49 (0)351 2801-390
Company name
Address
Street
Town/Postcode
Shape and dimensions of grinding wheel (if not ISO standard, please send a drawing as well)
Grinding method (e.g. surface, internal cylindrical or external cylindrical grinding)
Grinding machine
Operating speed v C in m/s or grinding spindle speed of rotation n S in rpm
Description of workpiece (e.g. valve)
Material, hardness of material
Surface quality required (R a or R z or R t in μm)
Grinding overmeasure, infeed control in mm
Wet or dry grinding
Specification used to date
Optimization objective
Annual requirement for this item
13
H er m es Sup er abr asives Id ent ificat ion S ys t em
Shapes and dimensions
14L1R
D/J
Shapeofwheel
Diameterofwheel
x
T
x
Thicknessofwheel
H
- U - R - X
Borediameter
Coatingdimensions
Core body basic shape
Grinding coating shape
14
L
1
2
A
AA
B
BF
3
4
BT
C
D
E
6
9
EF
ET
F
GN
K
L
M
Q
60°
10
11
<=30°
12
14
14
>30° bis <60°
13
TheshapesofCBNandDiamondbondedabrasivesaredescribedinDINstandard69800.
Theshapesofgrindingwheelsaredescribedbymeansof4primarycharacteristics:
1.Basicshapeofcorebody;2.Shapeofgrindingcoating;3.Arrangementofgrindingcoating;4.Modification.
Arrangement of grinding coating
Modification
1
R
1
2
On circumference
On the side, one side
3
4
On the side, two sides
Inner chamfer or inner curve
5
6
Outer chamfer or outer curve
Part of the circumferential surface
B
C
H
Countersink for
cylinder bolts
Countersink for
countersunk bolts
Continuous
bores
M
P
R
Continuous and
threaded bores
Coating relieved on
one side
Coating relieved on
both sides
Q
Y
V
Inside
Concave on inside
Concave coating
W
7
8
K
Part of the side surface
Continuous
With keyway
With shaft or spindle
NEW
NEW
9
10
Corner
Inside
S
SS
Segmented
Segmented and slit
15
H er m es Sup er abr asives Id ent ificat ion S ys t em
Specification (e.g. 23B 126 P5 V241 150 125 m/s)
Manufacturers mark vitrified bonded CBN and Diamond abrasives in accordance with a company-specific code. On the following pages, we show the Hermes Identification System using the example specification mentioned above.
Type
Grit type
Grit size and surface quality
23B
126
Application
FEPA
Nominal
mesh width
[µm]
US-Mesh
RZ
[µm]
Rt
[µm]
Ra*
[µm]
6.3
6 - 12
10
8 - 15
3000
0.17
0.10 - 0.30
0.02
1800
0.30
0.20 - 0.50
0.04
25
20 - 30
800
0.43
0.52
0.30 - 0.70
0.40 - 0.80
0.06
0.08
46
38 - 45
325/400
0.65
0.50 - 1.00
0.10
64
53 - 63
230/270
0.77
0.86
0.60 - 1.20
0.65 - 1.40
0.12
0.14
76
63 - 75
200/230
1.00
1.07
0.70 - 1.60
0.80 - 1.70
0.16
0.18
91
75 - 90
170/200
1.20
0.90 - 1.90
0.20
107
90 - 106
140/170
1.45
1.70
1.95
1.10 - 2.30
1.30 - 2.70
1.50 - 3.00
0.25
0.30
0.35
CBN
11B
29B
High performance
e.g. for external cylindrical and internal cylindrical grinding
12B
22B
28B
High performance
e.g. for internal cylindrical grinding
13B
16B
23B
High performance
e.g. for for external cylindrical and surface grinding
10B
20B
30B
Standard
e.g. for external cylindrical, internal cylindrical
and surface grinding
Diamond
12D
14D
High performance
e.g. for external cylindrical, internal cylindrical
and surface grinding
126
106 - 125
120/140
10D
11D
Standard
e.g. for external cylindrical, internal cylindrical
and surface grinding
2.20
2.45
1.70 - 3.40
1.90 - 3.80
0.40
0.45
151
125 - 150
100/120
3.45
4.60
2.70 - 5.20
3.70 - 7.00
0.65
0.90
181
150 - 180
80/100
5.45
6.35
5.20 - 9.50
4.50 - 8.20
1.10
1.30
213
180 - 212
70/80
7.10
6.00 - 10.00
1.50
301
250 - 300
50/60
8.45
11.20
15.10
19.40
20.60
7.10 - 12.50
9.60 - 16.50
13.00 - 22.00
17.00 - 28.00
18.00 - 30.00
1.80
2.50
3.50
4.50
5.00
External cylindrical method, further dependent on dressing conditions, materials.
This information is only intended as a guide! The surface values which can be achieved are significantly affected by the grinding method, the conditions of use and
the concentration of hard substance in the coating specification.
* CLA (Centre Line Average)
[µ"] = R a [µm] / 0.0254
RMS (root mean square average) [µ"] ~ CLA [µ"] / 0.85
16
Hardness
Structure
P
5
Code
letter
Hardness
Use
Code numbers
Description
H, I, JOT,
K
soft
primarilyforheat-sensitive
materials
2-3
densestructure
L, M, N, O
medium
standard
4-7
mediumstructure
P, Q, R, S
hard
forverygoodprofileand
edgestability
8 - 10
openstructure
T, U, V,
W, X
veryhard
forhighprofileandedgestability
(e.g.Quickpoint)
Number / 2 ... 8
withartificalpore-former
Explanation of surface values
1
2
3
4
5
R Z2
R Z4
R Z1
Rt
Ra
R Z3
R max
R Z5
Reference profile
Actual profile
Mean profile
Base profile
Area
Ra
Rz
Rt
Rmax
arithmetical mean roughness value
averaged surface roughness
maximum surface roughness
maximum individual surface roughness
17
H er m es Sup er abr asives Id ent ificat ion S ys t em
Specification (e.g. 23B 126 P5 V241 150 125 m/s)
Bond
Concentration
V241
150
Name
Hardness
Grinding process
V04
Moderate
Universal
Concentration
Per cent by
volume of
Diamond/CBN
CBN
in carat/cm3
Diamond
in carat/cm3
V31
Internal cylindrical grinding
25
6.30%
1.09
1.10
V24
Internal cylindrical and surface grinding
50
12.50%
2.17
2.20
V42
External cylindrical grinding
75
18.80%
3.26
3.30
V242
Internal cylindrical grinding
100
25.00%
4.35
4.40
V41
External cylindrical grinding and
surface grinding
125
31.30%
5.44
5.50
150
37.50%
6.53
6.60
175
43.80%
7.61
7.70
200
50.00%
8.70
8.80
220
55.00%
9.57
9.68
240
60.00%
10.44
10.56
V241
18
Extremely
strong
External cylindrical grinding e.g. cam shape
Permitted circumferential speed
125 m/s
Maximum operating speed
(m/s)
Number of stripes
below 50
none
50
1xblue
63
1xyellow
80
1xred
100
1xgreen
125
1xblue+1xyellow
140
1xblue+1xred
Coding colour of stripes
19
A pplic at ion r e c omm endat ions
Influence of process and
tool parameters on outcome
Grinding force (y)
Grindability
of steel (x)
high
high
y
y
y
y
difficult
x
easy
low
difficult
x
easy
low
y
y
y
y
low
x
high
low
low
x
high
low
low
x
high
low
high
high
high
high
y
y
y
y
low
x
high
low
low
x
high
low
low
x
high
low
high
high
high
high
y
y
y
y
poor
x
high
low
poor
x
high
low
poor
x
high
low
high
high
high
high
y
y
y
y
low
x
high
low
low
x
high
low
low
x
high
low
high
high
high
high
y
y
y
y
low
x
high
low
low
x
high
low
low
x
high
low
high
high
high
high
y
y
y
y
low
Hardness (x)
low
high
low
Grit size (x)
easy
high
low
Concentration (x)
x
high
low
Effective
roughness from
dressing (x)
difficult
high
low
Lubricity of cooling
lubricant (x)
Burning risk (y)
high
low
Metal removal rate
(Infeed control,
feed rate) (x)
Roughness (y)
high
low
Cutting speed (x)
Wear (y)
low
x
high
low
low
x
high
low
low
x
high
low
high
high
high
high
y
y
y
y
low
low
x
high
low
low
x
high
low
low
x
high
low
difficult
x
easy
low
x
high
low
x
high
poor
x
high
low
x
high
low
x
high
low
x
high
low
x
high
Structure
Structure is specified mainly by the process and should only be varied within narrow limits. In general, it
holds true that the longer the contact length, the more open the structure (the higher the structure number).
Bond
Hermes uses the bond best suited to the process.
20
Selecting machine parameters
for CBN grinding
Grinding process und machine parameters
Settings
External cylindrical grinding
Traverse grinding
Cutting speed vC
30 - 140
m/s
Workpiece speed v W
15 - 200
m/min
Workpiece advance v fa
0.5 x bS x nW mm/min
Infeed ae
0.005 - 0.05 mm
Plunge grinding
Cutting speed vC
30 - 140
m/s
Workpiece speed v W
100 - 200
m/min
Advance speed v fr
0.1 - 2.0
mm/min
Centerless grinding
Cutting speed vC
30 - 100
m/s
Workpiece speed v W
30 - 150
m/min
Workpiece advance v fa
50 - 2000
mm/min
Infeed ae
0.005 - 0.05 mm
Surface grinding
Reciprocating grinding
Cutting speed vC
25 - 60
m/s
Workpiece speed v W
10 - 20
m/min
Infeed ae
<= 20% of grit size
Crossfeed
0.5 x bS mm
Cutting speed vC
15 - 80
m/s
Workpiece speed v W
30 - 120
m/min
Infeed ae
0.001 - 0.02 mm
Crossfeed
Short-stroke oscillation
Internal cylindrical grinding
Oscillation grinding
Plunge grinding
Cutting speed vC
35 - 80
m/s
Workpiece speed v W
60 - 120
m/min
Advance speed v fr
0.1 - 2.5
mm/min
21
A pplic at ion r e c omm endat ions
Cooling lubricants
Note: In principle, vitrified bonded CBN/diamond abrasives should be used only in wet-grinding methods.
Conventional cooling lubricants perform the tasks “lubricate”, “cool” and “flush” to varying degrees of satisfaction.
A distinction is generally made between three types of cooling lubricants:
1. Grinding oils with EP additives
In addition to their cooling action, their good lubricating properties have a favourable impact primarily on friction forces, thus allowing
longer tool lives to be achieved for better surface qualities.
2. Emulsions (water with 0.2 - 15% oil fraction)
Good wettability, high level of heat dissipation and consequently good cooling action. Suitable for CBN and diamond grinding wheels at elevated metal removal rates and moderate roughnesses.
3. Transparent solutions of synthetic products with EP additives
In addition to good wettability, their transparency should be mentioned as a particular benefit. It allows the grinding process to be observed better.
Suitable for CBN and diamond grinding wheels at elevated metal removal rates and moderate roughnesses.
Product comparison
Cooling lubricant
Lubricating action
Cooling performance
Cleaning effect
Resistance to ageing
Mineral oil, pure
very good
poor
moderate
good
Emulsion 15%
good
moderate
good
poor
Emulison 5%
moderate
good
good
moderate
Synthetic solution 3%
poor
very good
very good
very good
Semi-synthetic solution 3%
good
good
good
good
Comparison of applications
Material
Abrasive
Grinding process
Reciprocating
grinding
Hardened metal
Hardened metal + steel
Ceramic
Spray-on alloys with
tungsten carbide
Diamond
HSS
Chrome steel
Metal spray-on alloys
CBN
Long-chipping types of steel
e.g. 100Cr6, 16MnCr5
Special materials
CBN
22
Creep
feed
grinding
X
X
X
X
X
X
X
X
X
X
X
X
Cooling lubricant
recommended
Water fraction
Emulsion
Emulsion
Fully-synthetic solution
Semi-synthetic solution
98 - 95%
95 - 90%
98 - 97%
98 - 97%
Emulsion
Fully-synthetic solution
Semi-synthetic solution
Fully-synthetic solution
Semi-synthetic solution
Mineral oil with EP if appropriate
98 - 95%
97 - 95%
97 - 96%
Emulsion
Mineral oil with EP if appropriate
95 - 80%
Dressing methods and parameters
Note:
It is generally necessary to dress the bonded abrasive after changing the tool (to generate concentricity) and during the
grinding process once the tool life criterion (surface quality, profile deviation) has been reached.
Dressing method
Diamond profile roller dresser
1
Vfrd
2
Diamond form roller dresser
VR
VR
Vfad
Vfrd
Vsd
Vsd
CBN grinding wheel
CBN grinding wheel
3
4
Diamond dressing wheel
7°
VR
Vfad
Vrel = 0
Vfrd
CBN grinding wheel
Steel profile roll
Vsd
CBN grinding wheel
Application recommendations
Variables affecting dressing outcome
Dressing/speedratio
Dressing method
qd
Semi/counterdirection
1,2,3
1,2,3
vsd
2,3
Peripheraldresserspeed
vR
1,2,3
Transverseoverlapratio
Ud
2,3
Dressinginfeed
aed
2,3
Dressingfeedrate
v frd
1,4
Peripheralgrinding
wheelspeed
Contactpressure
Dressingcontactwidth
Formulae
Transverse overlap ratio
Ud =
bR .
n
vfad sd
Dressing/speed ratio
v
qd = R
vsd
4
bR
2,3
Recommended settings for dressing methods 2 + 3
qd > 0.5
aed = 2; aed – total = max. 10% of grit diameter
Ud = 5 (Ud:numberoftimesdressingtoolcontactsapointonthecircumferentialsurfaceoftheabrasivetool)
23
A pplic at ion r e c omm endat ions
Dressing methods and parameters
Effect of speed ratio and dressing infeed on effective surface roughness
16
14
Radial feed
for dressing
[µm/revolution]
frd = 0.72
frd = 0.54
frd = 0.36
frd = 0.18
Effective surface roughness (µm)
12
10
8
6
4
2
Same direction
0
2
1.5
Counter direction
1
0.5
0
Speed ration q
-0.5
-1
Source: Schmitt, R. – Dressing grinding wheels with diamond-coated rolls - dissertation from the Technical University in Braunschweig, Germany
24
-1.5
-2
Key data in the grinding process
G ration
The G ratio allows a direct comparison to be made between two different grinding wheels in the same grinding process with identical parameters.
The ratio is calculated as follows:
G =
Volume of workpiece reduced [mm3]
Wheel coating consumed [mm3]
General guidelines
Diamond on hardened metal
CBN on HSS
50 - 300
150 - 800
Relative metal removal rate Q'W
The relative metal removal rate describes the removal rate of a grinding wheel per second per millimetre of grinding wheel thickness. This allows a direct comparison of different grinding processes to be made.
Formulae for calculating Q'W [mm3/mm . s]:
Q'W =
Key
ae . vt
Surface and creep feed grinding
60
a e
Infeed control [mm]
v t
Advance speed [mm/min]
DW Diamater of workpiece [mm]
Q'W =
Q'W =
ae . nW . D W . π
60
vf . DW . π
60
External cylindrical longitudinal grinding
nW Speed of rotation of workpiece [rpm]
v f
Radial advance speed [mm/min]
External cylindrical infeed grinding
25
In t er n e t
Why not visit our website?
Virtually all the information
useful for planning and purchasing
Hermes Bonded Abrasives
is available on our website which
is based on a database and is
equipped with numerous other
functions:
•
•
•
•
New products
Detailed product information
Application solutions
Information about the company
It goes without saying that the
Hermes site is multilingual, so it
can be used all over the world.
This website is constantly being
updated and is an important
information platform.
www.hermes-schleifkoerper.de
You have the option of downloading information material
via the Web for instant
availability.
Our website also lists all your
relevant contacts, whether field or
office-based staff.
26
For more information
about Hermes bonded abrasives
Hermes Schleifkörper GmbH
Lohrmannstrasse21
01237Dresden,Germany
Phone+493512801-0
Fax+493512801-390
[email protected]
www.hermes-schleifkoerper.de
33E21.30.Therighttomakeamendmentsisreserved.