chapter 3 material removal mechanisms

23

3 Material Removal Mechanisms

3.1 SIGNIFICANCE

3.1.1 INTRODUCTION

Knowledge of the basic principles of a process is a prerequisite for its effective improvement andoptimization. During grinding, surface formation is one of the basic mechanisms. In the case ofcutting with geometrically defined cutting edges, a singular engagement of the cutting edge definesthe removal mechanism. The consequent removal mechanisms can be directly observed by meansof modern investigation methods.

In the case of grinding, the investigation of removal mechanisms is complicated due to manydifferent factors. The first problem is posed by the specification of the tool. The abrasive grainsare three-dimensional and statistically distributed in the volume of the grinding wheel. The geometryof the single cutting edges is complex. Moreover, there is a partially simultaneous engagement ofthe cutting edges involved in the process. The surface formation is the sum of these interdependentcutting edge engagements, which are distributed stochastically. Furthermore, the chip formationduring grinding takes place within a range of a few microns. The small chip sizes make theobservation even more difficult.

3.1.2 DEFINING BASIC BEHAVIOR

In spite of the complexity, some statements can be made on the removal mechanisms, surfaceformation, and the wear behavior during grinding. Analogy tests and theoretical considerations onthe basis of the results of physical and chemical investigations are used for this purpose. In thepast few years, chip and surface formation have been modeled with the help of high-performancecomputers and enhanced simulation processes.

• Indentation tests—In analogy tests, the engagement of the cutting edge in the materialsurface is investigated first. The advantage of this method is that single cutting edgescan be investigated before and after the process, and their geometry is known. With thehelp of so-called indentation tests with singular cutting edges, the material behavior toa static stress can be observed without the influence of the movement components typicalfor grinding. On the basis of these indentation tests, elastic and plastic behavior as wellas crack formation can be observed in the case of brittle-hard materials at the momentthe cutting edge penetrates the material.

• Scratch tests—A further method is the investigation of the removal mechanisms duringscratching with single cutting edges, which allows the accurate examination of thegeometry and the wear of the cutting edges. Contrary to the indentation tests, there ischip formation during this test method. Furthermore, the influence of different coolinglubricants can be investigated.

• Cutting edge geometry—A further prerequisite of a comprehensive understanding of thematerial removal during grinding is the geometrical specification of the single cuttingedges. This mainly takes place in analogy to the geometrical relations at geometricallydefined cutting edges.

© 2007 by Taylor & Francis Group, LLC

24 Handbook of Machining with Grinding Wheels

• Thermal and mechanical properties—The thermal and mechanical characteristics of theactive partners of the grinding process also have a significant influence. Heat is generatedin the working zone through friction. This contact zone temperature influences themechanical characteristics of the workpiece as well as of the tool.

• Surface modification—As a result of the removal mechanisms, the subsurface of themachined workpiece is influenced by the grinding wheel due to the mechanical stress.Residual stresses develop depending on the specification of the machined workpiecematerial. These stresses can have a positive effect on component characteristics; hence,they are in some cases specifically induced. Due to the mechanical stresses, cracks orstructural and phase changes may occur on the subsurface that have a negative effect onthe component characteristics.

This shows the complexity of the mechanisms of surface formation during grinding. The betterthe surface formation is known, the more specifically and accurately the process parameters, thetool specification, and the choice of an eligible cooling lubricant can be optimized.

3.2 GRINDING WHEEL TOPOGRAPHY

3.2.1 INTRODUCTION

In the case of grinding, the cutting process is the sum of singular microscopic cutting processes,whose temporal and local superposition leads to a macroscopic material removal. As a consequence,the cause-and-effect principle of grinding can only be described on the basis of the cutting behaviorof the individual abrasive grains [Sawluk 1964]. The most important parameter is the number ofthe currently engaged cutting edges [Kassen 1969]. An exact determination of the geometricalengagement conditions of the single cutting edges, however, is not possible for manufacturingprocesses like grinding or honing. Due to the stochastic distribution of the geometrically not definedcutting edges, their position and shape cannot be exactly determined.

Therefore, the position, number, and shape of the abrasive grains are analyzed statistically andrelated to the process kinematics and geometry to achieve a specification of the engagementconditions of the abrasive grain. Thus, grinding results can be related to events at the effective areaof grinding contact for particular input values of machine and workpiece parameters and otherspecifications of the process. The main cutting parameters of the removal process are the theoreticalchip thickness, length, and engagement angle. Knowing the overall relations between input values,cutting and chip values, as well as process output values, the behavior of the process can becohesively described and used to improve the set-up of the machining process. This implies a wheelspecification suitable for the grinding situation and the choice of parameters leading to an econom-ical grinding process.

Different authors have described the material removal mechanisms of diverse grinding pro-cesses. Thereby, a distinction is made between topography, uncut chip thickness, grinding force,grinding energy, surface, and temperature models in relation to different basic models [Kurrein1927, Pahlitzsch and Helmerdig 1943, Reichenbach et al. 1956, Kassen 1969, Werner 1971, Inasaki,Chen, and Jung 1989, Malyshev, Levin, and Kovalev 1990, Lierath et al. 1990, Toenshoff et al.1992, Paulmann 1990, Marinescu et al. 2004].

3.2.2 SPECIFICATION OF SINGLE CUTTING EDGES

The geometry of single cutting edges may be described statistically by measurement of cuttingedge profiles. The depiction of the form of a cutting edge of an abrasive grain represents the averageof all measured geometries. The main characteristic of the cutting edges acting during grinding isthe clearly negative rake angle (Figure 3.1).


Material Removal Mechanisms 25

3.3 DETERMINATION OF GRINDING WHEEL TOPOGRAPHY

3.3.1 INTRODUCTION

The determination of the grinding wheel topography can be divided into static, kinematic, anddynamic methods [Bruecher 1996]:

• Static methods—All abrasive grains on the surface of the grinding tool are considered.The kinematics of the grinding process is not taken into account.

• Dynamic methods—In this process, the number of actual abrasive grain engagementsare measured. The active cutting edge number is the totality of cutting edges involvedin the cutting process.

• Kinematic methods—Kinematic methods combine the effects of the kinematics of theprocess with the statically determined grain distribution for the specification of microki-nematics at the single grain, that is, for the determination of cutting parameters.

3.3.2 STATIC METHODS

If static assessment methods are used, basically all cutting edges in the cutting area are includedin the topography analysis. There is no distinction, whether a cutting edge of the grinding processis actively involved or not in the cutting process. Static processes are independent of the grindingconditions [Shaw and Komanduri 1977; Verkerk 1977].

Figure 3.2 shows a schematic section of a cutting surface of a grinding wheel. All abrasivegrains protruding from the bond have cutting edges—the so-called static cutting edges. Sincegrains usually have more than one cutting edge, the distance between the static cutting edgesdoes not correspond to the average statistical grain separation on the grinding wheel. Therefore,instead of the distance between the static cutting edges, the number of cutting edges is specifiedper unit length, that is, the static cutting edge number Sstat, the cutting edge density per surfaceunit Nstat, or the number per unit volume of the cutting area Cstat [Daude 1966, Lortz 1975,Kaiser 1977, Shaw and Komanduri 1977, Verkerk 1977, Rohde 1985, Treffert 1995, Marinescuet al. 2004].

FIGURE 3.1 Average shape and analytic description of a cutting edge. (From Koenig and Klocke 1996. Withpermission.)

Direction of cut

Chip thickness hcu

Cutting edgeradius rs

αγ

Abrasive grain



3.3.3 DYNAMIC METHODS

In contrast to static methods, dynamic methods depend on the grinding conditions. Giving consid-eration to the grinding process, the parameters, and the geometrical engagement conditions, infor-mation is obtained about which areas of the effective surface of the grinding wheel are actuallyinvolved in the process [Verkerk 1977, Gaertner 1982].

Figure 3.3 shows some of the existing cutting edges actively involved in the process. Thenumber and density of the active cutting edges Sact and Cact are therefore smaller than those of thestatic cutting edges Sstat and Cstat. Their value is mainly determined by the geometric and kinematicparameters. As a result of constant wheel wear and of the consequent topography changes of thewheel, the cutting edge density has continually changing values.

3.3.4 KINEMATIC SIMULATION METHODS

In the kinematic approach, the process kinematics is additionally taken into account for thespecification of the effective cutting area. On the basis of the kinematically determined cuttingedge number, the trajectories of the single grains are reproduced when considering the grinding

FIGURE 3.2 Static cutting edges. (From Koenig and Klocke 1996. With permission.)

FIGURE 3.3 Kinematic cutting edges. (From Koenig and Klocke 1996. With permission.)

Abrasive grain

Static cuttingedge spacing

S2S1

S3

S4S5 S6 S7 S8

S9

BondGrinding wheel

Lst

S1S3

S5 S7 S9

BondAbrasivegrain

Workpiece feed speed Vw

Grinding wheelperiphral speed Vs

Kinematicaledge distance

Workpiece

S2S8

S4 S6



process, the setting parameters, and the geometrical engagement conditions [Lortz 1975, Gaertner1982, Steffens 1983, Bouzakis and Karachaliou 1988, Stuckenholz 1988, Treffert 1995].

3.3.5 MEASUREMENT OF GRINDING WHEEL TOPOGRAPHY

Figure 3.4 summarizes different methods for measuring the topography of grinding wheels. In thecase of the carbon paper method, white paper and carbon paper are put between the grinding wheeland a slightly conical, polished plastic ring. The grinding wheel topography is reproduced on thewhite paper by rolling the grinding wheel on the plastic ring. Due to the conical shape of the ring,the measurement of the cutting edge distribution is expected to be dependent on the cutting areadepth [Nakayama 1973].

3.3.6 ROUGHNESS MEASURES

Various surface parameters, RZ, RK, RVK, and RPK, are available as measures of topography and, inparticular, the maximum profile height, Rp, is useful due to its integrating character for the speci-fication of the grinding wheel topography [Schleich 1982, Werner and Kentner 1987, Warneckeand Spiegel 1990, Uhlmann 1994, Bohlheim 1995]. A further value derived from static methodsis the static cutting edge number per length or surface unit N′S or NS [Daude 1966, Lortz 1975,Kaiser 1977, Shaw and Komanduri 1977, Verkerk 1977, Rohde 1985, Treffert 1995]. The cuttingedges are determined on the basis of the envelope curve of the effective area of the grinding wheels,which is defined by the external cutting edges. With increasing depth, the cutting edges penetrateequidistant intersection surfaces or lines. Similar to a material ratio curve, a frequency curve ofthe static cutting edge numbers is formed depending on the cutting edge depth z S .

FIGURE 3.4 Methods for characterizing topography of grinding wheels. (From Bruecher 1996. With permission.)

Methods for the determination of the grinding wheel topography

Static method Dynamic method Kinematical method

In-processPost-process Post-process Post-process

Carbon paper method-static cutting edgenr. NS

Photoelectr. method-act. cutting edge nr.

NSact

Scratching-method-act. cutting edge nr.

NSact

Profile method-surface parameters(RZ, Rp, RK, RVK, RPK)-stat. cutting edge nr. NScutting edge density CS

Profile method,kinematical simulationof the process-kin. cutting edgenumber NSkin

Piezoelectr. method-act. cutting edge nr.

NSact

Thermoelectr. method-act. cutting edge nr.

NSact

Reproduction method-spec. s. roughness (Rtb)-end s. rough. (Rtaus)-effective s. rough. (Rtw)

Transition resistance-act. bond ridge

Microscop. methoda. grinding wheelb. print-qual. impression-statistical counting-stat. cutting edge nr. NScutting edge density CS



3.3.7 QUALITATIVE ASSESSMENT

SEM, optical, and stereo-microscopic images are used for the qualitative evaluation of wearprocesses [Schleich 1982, Stuckenholz 1988, Dennis and Schmieden 1989, Warnecke and Spiegel1990, Wobker 1992, Uhlmann 1994, Marinescu et al. 2004].

3.3.8 COUNTING METHODS

Microscopic processes can, however, also be used to make quantitative statements on the state ofthe grinding wheel effective area. For this purpose, grains or different wear characteristics werestatically counted [Buettner 1968, Bohlheim 1995]. The measurements are either carried out directlyon the grinding wheel surface or indirectly on a print of the surface.

3.3.9 PIEZO AND THERMOELECTRIC MEASUREMENTS

Piezoelectric and thermoelectric processes for the determination of the active cutting edge numberare based on the measurement of force signals or temperature peaks of single active cutting edges[Daude 1966, Kaiser 1977, Shaw and Komanduri 1977, Verkerk 1977, Damlos 1985]. The piezo-electric process is only applicable for small contact surfaces, since it has to be ensured that nomore than one cutting edge is engaged in the contact zone at any time. Small samples of a widthof circa 0.3 mm [Kaiser 1977] are ground with relatively small feed. In the thermoelectric process,a thermocouple wire of a small diameter is divided by a thin insulating layer from the surroundingmaterial within the workpiece. Every active cutting edge or bond ridge destroys the insulating layerand creates a thermocouple junction through plastic deformation. This leads to the emission of ameasurable thermoelectric voltage signal from which a corresponding temperature can be estab-lished. Therefore, the material has to be electrically conductive and sufficiently ductile. Hence, thisprocess cannot be applied to ceramics [Shaw and Komanduri 1977]. A contact resistance measure-ment can be applied for diamond and cubic boron nitride (CBN) grinding wheels with an electricallyconducting bond for the purpose of distinguishing between active cutting edges and active bondridges [Kaiser 1977].

3.3.10 PHOTOELECTRIC METHOD

Photoelectric methods according to the scattered light principle are based on light reflected by thecutting area and collected using a radiation detector. In this method, the scattered light distributionand the duration and number of light impulses in the direction of the regular direct reflection areevaluated [Werner 1994].

3.3.11 MIRROR WORKPIECE METHOD

The topography of the grinding wheel can be depicted in a control workpiece. For this purpose, amirroring workpiece angled diagonally to the grinding direction is ground once. Counting the scratchmarks, a conclusion can be drawn to the number of active cutting edges per unit surface area. Sincethe scratch marks of successive cutting edges might overlap each other, it is not possible to determinethe overall number of engaged cutting edges [Shaw and Komanduri 1977, Verkerk 1977].

3.3.12 WORKPIECE PENETRATION METHOD

A further method is the penetration of a thin steel plate or a stationary workpiece by the effectivearea of the grinding wheel. The roughness profile of the ground test piece results from theoverlapping of the profiles of the cutting edges active in the removal process. The roughnesses ofthe test pieces are called specific surface roughness, Rtb, end surface roughness, Rtaus, or effectivesurface roughness, Rtw [Karatzoglu 1973, Saljé 1975, Fruehling 1976, Weinert 1976, Jacobs 1980,



Gaertner 1982, Rohde 1985, Stukenholz 1988]. These processes are suitable for a comparativeassessment of the cutting edge topographies. It is, however, not possible to make any statementson the shape and number of cutting edges [Lortz 1975, Werner 1994].

3.4 KINEMATICS OF THE CUTTING EDGE ENGAGEMENT

In order to compare a variety of grinding processes, it is necessary to define general and comparableprocess parameters. With these parameters, different processes can be compared with each otherallowing an efficient optimization of the process. The most important grinding parameters are thegeometric contact length, lg, chip length, lcu, and the chip thickness, hcu.

The kinematics and the contact conditions of different grinding processes are represented inFigure 3.5. They constitute the basis of many process parameters.

Neglecting the elastic deformation of the active partners of the grinding process, the grindingwheel penetrates the workpiece with the real depth of cut, ae. The arc contact length is defined bythe geometric contact length, lg:

(3.1)

For the same depth of cut values, different contact lengths result in the case of cylindrical andsurface grinding. The equivalent wheel diameter deq is a calculation method of representing geo-metric contact length independent of the grinding process, where

(3.2)

applies to the equivalent grinding wheel diameter in external cylindrical grinding. In the case ofinternal cylindrical grinding, the equivalent grinding wheel diameter is:

(3.3)

FIGURE 3.5 Contact conditions for different peripheral grinding processes.

l a dg e eq

= ⋅

dd d

d deqw s

w s

=⋅+

dd d

d deqw s

w s

=⋅−

a

c

e

db

(A) Surface or face grinding

c

de

(B) Cylindrical grinding

(a) Grinding wheel, (b) Workpiece, (c) Cutting speed, (d) Feed speed, (e) Resulting effective speed



The equivalent grinding wheel diameter deq indicates the diameter of the grinding wheel, whichhas the same contact length in surface grinding. Thus, the equivalent grinding wheel diametercorresponds to the actual grinding wheel diameter in surface grinding.

The movement of the wheel relative to the workpiece is put in related to the speed quotient q.In up-grinding, it is negative:

(3.4)

In peripheral grinding with rotating grinding tools, the cutting edges move on orthocycloidal pathsdue to the interference of the speed components.

Figure 3.6 demonstrates the paths of two successive cutting edges. Both points have the sameradial distance from the wheel center. The path the center travels between the two engagements ofthe wheel results from the feed movement and the time required.

The cutting edge engagement and the resulting uncut chip parameters depend on the statisticalaverage of the cutting edges distributed on the grinding tool. The equation

(3.5)

relates the maximum uncut chip thickness hcu to the cutting edge distribution, the grinding param-eters, and the geometric values [Kassen 1969]. The mean maximum uncut chip cross-sectionalarea is a further characteristic parameter of the grinding process. Like the maximum uncutchip thickness hcu, it depends on the parameters, the cutting edge distribution, and the geometry ofthe active partners of the grinding process. The mean maximum uncut chip cross-sectional areais calculated from

(3.6)

FIGURE 3.6 Contact conditions for two cutting edges.

Workpiece

a

M′ M

S2

S1

vwt

p

A ∆han

ωst ψ

ψ

M = Center of grinding wheelS1 = Leading cutting edgeS2 = Trailing cutting edge

qv

vs

f

= ±

h kl

C

v

v

a

dcuc

e

eq

f=

1

α β γγ

Qmax

Qmax

QA

Cv

v

a

dN

f

c

e

eqmax

( )=

−

− −2

1

1 12

β

α α



On the basis of these values, a theoretical assessment can be made of the grinding process.There is a direct relation between the cutting parameters and the resulting surface quality. Equations(3.5) and (3.6) lead to the conclusion that the surface quality improves with increasing cuttingvelocity and grinding wheel diameter. With increasing feed speed and higher depth of cut, however,the surface quality decreases.

The value of the uncut chip parameters, however, are only applicable to a real grinding processto a limited extent, since the kinematic relations were only derived for idealized engagementconditions [Marinescu et al. 2004]. The cutting process is not a simple geometric process; thereare also plastic and elastoplastic processes in real grinding so that chip formation is different fromthe geometric theory. It is for this reason that experiments are indispensable to gain knowledge andunderstanding about the material removal mechanisms.

3.5 FUNDAMENTAL REMOVAL MECHANISMS

3.5.1 MICROPLOWING, CHIPPING, AND BREAKING

The removal process during the engagement of an abrasive cutting edge on the surface of aworkpiece mainly depends on the physical properties between the active partners. A basic distinctioncan be made between three different mechanisms: microplowing, microchipping, and microbreaking(Figure 3.7).

In microplowing, there is a continual plastic, or elastoplastic, material deformation toward thetrace border with negligible material loss. In real processes, the simultaneous impact of severalabrasive particles or the repeated impact of one abrasive particle leads to material failure at theborder of the traces. Ideal microchipping provokes chip formation. The chip volume equals thevolume of the evolving trace. Microplowing and microchipping mainly occur during the machiningof ductile materials. The relation between microplowing and microcutting basically depends on theprevailing conditions such as the matching of the active partners of the grinding process, grindingparameters, and cutting edge geometry.

Microbreaking occurs in case of crack formation and spreading. The volume of a chip removedcan be several times higher than the volume of the trace. Microbreaking mostly occurs during themachining of brittle-hard materials such as glass, ceramics, and silicon.

Hence, the mechanisms of surface formation during grinding consist of these three basicprocesses. Which of them predominates strongly depends on the workpiece material. Therefore,material removal mechanisms will be presented in Section 3.6 for ductile materials on one hand,and for brittle-hard materials on the other.

FIGURE 3.7 Physical interaction between abrasive particles and the workpiece surface. (From Zum 1987.With permission.)

Microplowing Microchipping Microbreaking



3.6 MATERIAL REMOVAL IN GRINDING OF DUCTILE MATERIALS

During grinding, the cutting edge of the grain penetrates the workpiece on a very flat path causingplastic flow of the material after a very short phase of elastic deformation. Since the anglebetween cutting edge contour and workpiece surface is very small due to the cutting edgerounding, no chip is formed initially. The workpiece material is only thrust aside, forms materialoutbursts or side ridges, and flows to the flank underneath the cutting edge [Koenig and Klocke1996]. Figure 3.8 shows the chip formation during grinding of ductile materials.

Only if the cutting edge penetrates the workpiece to a depth that the undeformed chip thickness,hcu, equals the so-called critical cutting depth, Tµ, does the actual chip formation begin. Sincedisplacement processes and chip formation occur simultaneously in the further process, it is crucialfor the efficiency of the material removal how much of the uncut chip thickness, hcu, is actuallyremoved as chip, and what the effective chip thickness, hcueff , is.

Grof [1977] has further differentiated the chip formation process during the machining ofductile materials with high cutting velocities. On the basis of experiments, he determined altogethersix phases of singular chip formation during grinding (Figure 3.9). In the first quarter of the contactlength (phase 1), the engaging abrasive grain first makes a groove, causing plastic and elasticdeformation in the material, which is then thrust aside from the groove. The surface is presumedto consolidate during this contact phase [Werner 1971] without chip formation.

Through the further advance of the cutting edge (phase 2), a flow chip is removed with anearly parallelogram-shaped cross section. This chip is compressed and bent in dependence ofthe pore space. Due to the large point angle of a cutting edge, the chip is very flat and offersa big surface for heat discharge through radiation and convection. In case of small infeeds orfeeds, the working contact ends in the third phase, forming almost exclusively thread-shapedchips.

In case of large infeeds and feeds, the cutting edge penetrates the material deeper. This leadsto a distinctive shear zone at approximately three fourths of the maximum engagement lengthresulting in strong heat development (phase 3). The strong material accumulation through the highpressure causes an increase of the contact zone temperature. Due to the small effective surface ofthe cooling lubricant, this heat cannot be discharged. This leads to a melting of the formed chipabove the plastic state.

FIGURE 3.8 Removal process during the machining of ductile materials. (From Koenig and Klocke 1996.With permission.)

FtS FnS

veη

Chip

hcu

Materialoutbursts

Elasticdeformation,friction grain/

material

Elast. and plast.deformation,friction grain/material, inner

Elastic and plasticdeformation and chip removalfriction grain/material inner

material friction

I II III

Tµhcu eff



If the cutting edge engagement is terminated in this phase, tadpole-shaped chips are formed(phase 4). If the engagement takes place along the entire contact length, the whole material isliquefied in the pore space after the thread-shaped chip falls off (phase 5).

Due to the surface tension, the molten chip becomes spherical after leaving the contact surface.This takes place in a zone where there is none or only a small amount of cooling lubricant (phase 6).The fact of sphere formation has been observed by other researchers as well [Hughes 1974,Marinescu et al. 2004].

A further model of cutting edge engagement has been presented by Stephens [1983]. The cuttingedge engagement can be ideally considered as an even-yielding process. In this model, the contactzone is divided into layers that are arranged parallel to the movement axis. The material starts

FIGURE 3.9 Removal process during the machining with high cutting speeds. (From Grof 1977. Withpermission.)

Phase 1

Phase 2

Phase 3

Phase 4

Phase 5

Phase 6



to yield in different directions at the cutting edge engagement. Thus, the individual layers are thrustaside at the point of engagement of the first cutting edge. When successive cutting edges engage,these areas are removed or thrust aside anew. Through these processes, the number of kinematiccutting edges increases partially in a subarea. Since these changes are statistically distributed tothe whole surface, there is overall no material accumulation.

The description shown in Figure 3.10 can serve as a model for the alternative description of alayer as an interaction of all displacement processes. A further prerequisite for the application ofslip line theory is the knowledge of the rheological properties of the material, which is supposedto be inelastic ideal plastic.

On the basis of these theoretical considerations and experimental investigations, statements canbe made on the friction conditions, which are decisively influenced by the lubrication [Koenig,Steffens, and Yegenoglu 1981, Steffens 1983, Vits 1985]. If the friction is increased, the criticalcutting depth decreases, which is additionally influenced by the radius of the cutting edge of the

FIGURE 3.10 Idealization of the cutting edge engagement through plain yielding. (From Steffens 1983. Withpermission.)

Cutting edge arrangementat the time t0

Cutting edge s1

s2s3

6 5 4 3 2 1Material displacement

to layers 2 and 3

Time t1, cutting edgeengagement s1

4 36 5 2 1Material displacement

to layers 3 and 2

Time t3, after cutting edgeengagement s3

4 36 5 2 1

Time t2, after cutting edgeengagement s2

Plain model of thecutting edge engagement

vc

Material displacementto layers 4 and 2



grain [Koenig et al. 1981, Steffens 1983]. Improved lubrication increases the plastic deformationtoward a higher critical cutting depth. Thus, there is a reduction of friction between the activepartners. With constant uncut chip thickness, hcu, the effective chip thickness, hcueff (thickness ofthe formed chip), decreases simultaneously with a reduction of friction [Steffens 1983, Vits 1985].

3.7 SURFACE FORMATION IN GRINDING OF BRITTLE-HARD MATERIALS

3.7.1 INDENTATION TESTS

Fundamental mechanisms of crack formation and spreading in the case of brittle-hard materialswere carried out by Lawn and Wilshaw [1975]. The stressing of a ceramic surface with a cuttingedge causes hydrostatic compression stress around a core area in the subsurface of the workpiece.This leads to a plastic deformation of the material (Figure 3.11a). If a certain boundary stress isexceeded, a radial crack develops below the plastically deformed zone (Figure 3.11b), whichexpands with increasing stress (Figure 3.11c).

After discharge, the radial crack closes in the initial phase (Figure 3.11d). During a furtherreduction of the stress state, axial stresses occur around the plastically deformed zone leading tolateral cracks below the surface (Figure 3.11e). The lateral cracks grow with decreasing stress. Thisgrowth can continue up to the surface of the material after complete discharge (Figure 3.11f) leadingto the break-off of material particles, which form a slab around the indentation zone [Lawn andWilshaw 1975].

3.7.2 SCRATCH AND GRINDING BEHAVIOR OF BRITTLE-HARD MATERIALS

Despite the low ductility, elastoplastic deformations occur as removal mechanisms alongside brittlefracture during the grinding of brittle-hard materials (Figure 3.12). Thereby, material removal throughbrittle fracture is based on the induction of microcracks. Ductile behavior of brittle-hard materials duringgrinding can be derived from the presumption that, below a threshold of boundary chip thickness definedby a critical stress, the converted energy is insufficient for crack formation and the material is plasticallydeformed [Bifano et al. 1987, Komanduri and Ramamohan 1994]. It is supposed, however, that cracksthat do not reach the surface are also formed under these conditions.

FIGURE 3.11 Mechanisms of crack spread in case of punctual stress. (From Lawn and Wilshaw 1975. Withpermission.)

+ + +

− −

(a) (b) (c)

(d) (e) (f )



Thus, not only the amount of stress, defined by the uncut chip thickness, is responsible for theoccurrence of plastic deformations, but also the above-mentioned hydrostatic compression stressbelow the cutting edge [Komanduri and Ramamohan 1994, Shaw 1995]. The transition from mainlyductile material removal to brittle friction is decisively determined by uncut chip thickness at thesingle grain by grain shape and by material properties. Large cutting edge radii promote plasticmaterial behavior and shift the boundary of the commencing brittle friction to larger engagementdepths. As a consequence, Hertzian contact stresses occur below the cutting edge, which causehydrostatic stress countering the formation of cracks [Uhlmann 1994].

Roth [1995] investigated removal mechanisms during the grinding of aluminum oxide ceramics.He observed the influence of different grain sizes of the material as well as different diamondgeometries on the material removal processes.

3.7.2.1 Fine-Grained Materials

When a scratching tool enters a fine-grained material, an entry section is formed by pure plasticdeformation. The length of the entry section strongly depends on the corner radius of the diamond. Ifthe material-specific shear stress is exceeded due to increasing scratching depth, a permanent deformationoccurs thrusting aside the material and causing bulgings along the scratched groove. The base of thescratch and the flanks are even and cover a thin layer of plastically deformed material (Figure 3.13a).

Different scratches occur in the material from a critical scratch depth on with the boundarycondition linked to it. Along with lateral crack systems observed during penetration tests, a mediancrack occurs through a succession of semi-elliptical radial cracks at the base that runs verticallyto the surface in the direction of the scratch. Similar scratch structures were observed during Vickersindentation tests. Also, V-shaped cracks are formed vertically to the surface and spread. The apertureangle is between 40° and 60° and grows with the increasing distance from the scratch. Obviously,they are crack structures that develop due to the shear stress of the tangential scratching force(shear scratches). If lateral cracks grow until the V-shaped cracks extend vertically to the surface,whole material particles break off on both sides of the scratch.

3.7.2.2 Coarse-Grained Materials

In the case of coarse-grained materials, the removal processes take place in a different way. A sharpdiamond plastically divides the grains in the structure under high energy input. With increasinginfeed cracks develop mainly along the grain boundary. This is accompanied by intercrystallinefailure, which leads to a break-off of grains near to the surface (Figure 3.13b).

FIGURE 3.12 Material removal process in machining of brittle-hard materials. (From Saljé and Moehlen1987. With permission.)

I II III

Chipfragments

Abrasive grain

Pressuresoftening ScratchingElastic

deformations

FnSFtS



In the case of blunt scratching grains, however, strong plastic deformations occur deeper, sincethe maxima of the shear stresses grow. Thin, strongly deformed flakes occur on the workpiecesurface. Through the extremely negative rake angle, the material is pushed forward and “extruded,”not provoking ductile material removal. The stress increases with further growing infeed until thestability is exceeded at the grain boundaries and the top grain layer breaks off in the form of wholeplates (Figure 3.13b).

On the basis of scratch tests and transmission electron microscopic (TEM) structure analyses,Uhlmann assembles the mechanisms of surface formation during ceramic grinding [Uhlmann 1994].

Surface formation can be divided into three types of mechanisms:

• Primary mechanisms, which act during the penetration of the cutting edges into thematerial

• Secondary mechanisms, which occur through the discharge by the first cutting edge andthe multiple stress by successive cutting edges

• Tertiary mechanisms, which prevent the spread of cracks in the case of materials with ahigh glass phase ratio.

The individual mechanisms are summarized in Table 3.1. These material-removal processes also occur during the machining of glass. For the industrial

application of optical glass, however, the conditions must allow a ductile surface formation. Thus,the development of an extensive crack system on the surface can be prevented. Figure 3.14summarizes the conditions for a model of ductile grinding of glass on the basis of scratch tests.According to this, a flattened blunt grain has to penetrate the material with a very small, singleuncut chip thickness. The single uncut chip thickness has to be below the critical chip depth,allowing an almost crack-free surface of glass materials.

FIGURE 3.13 Material removal mechanisms during the scratching of aluminum oxide. (From Roth 1995.With permission.)

Tabulargrain break-off

(b) Slight plastic deformation and break-offs in case of coarse-grained material

(a) Different crack systems and plastic deformation in case of fine-grained material

Friction crack

Lateral crack

Lateral crack

Lateral crack

Micro crack

Micro cracks

Heavily plasticallydeformed scales

Median crack

Median crack

Bulging

Scratching direction

Outburst



Monocrystal silicon is the most frequently applied substrate material in microsystems technol-ogy. The full range of physical properties of the material can only be exploited by a high degreeof purity, homogeneity, and crystal perfection. However, machining wafers induce damage in thesubsurface and its monocrystal structure. Therefore, the subsurface damage has to be removed bypolishing and etching prior to the processing of the electronic structures on the wafer front side.A concerted implementation of ductile material removal for the grinding process represents apossibility to improve the surface and subsurface quality as well as the economic efficiency of theentire process chain for wafer production [Holz 1994, Menz 1997, Kerstan et al. 1998, Tricardet al. 1998, Lehnicke 1999, Tönshoff and Lehnicke 1999, Klocke, Gerent, and Pähler 2000].

In grinding, surface formation mechanisms can be classified as ductile and brittle mechanisms.In brittle surface formation, microcracks and microcrack spread are generated in the subsurface bytensile stresses caused by the engagement of the abrasive grains of the grinding wheel into thesurface of the wafer [Cook and Pharr 1990, Lawn 1993, Holz 1994, Menz 1997, Brinksmeier et al.1998, Lehnicke 1999, Tönshoff and Lehnicke 1999]. In ductile surface formation, the inducedtensile stresses are insufficient to cause microcracks or crack propagation. The induced shear stressstrength causes deformation and movement of dislocations that promote ductile material behavior(Figure 3.14). This leads to better surface qualities and smaller depths of subsurface damage [Lawn1993, Menz 1997, Brinksmeier et al. 1998, Kerstan et al. 1998, Tönshoff and Lehnicke 1999].However, the basic mechanisms of ductile material removal are not known. It is further controversialwhether chip formation is actually taking place or whether brittle-effective mechanisms continueto cause chips, through which the grooves on the surface are covered by plastified material. In thiscase, the surface seems to be formed in a ductile mode. The subsurface below would neverthelessbe severely damaged by microcracks.

TABLE 3.1Mechanisms of Surface Formation [Uhlmann 1994]

Surface Formation

Primary MechanismsMechanical Stress Thermal StressMaterial condensationFormation of obstructionsCrack inductionBrittle break-off of particles in front of and alongside

the cutting edge (particle formation)

Plastification or melting of the material or material phases

Ductile removal of material in front of the cutting edge (chip formation)

Secondary MechanismsMechanical Stress Thermal StressBreak-off of particles behind and alongside the cutting edge

Induction of deep-lying cracks Spread of deep-lying cracks through multiple stress of successive cutting edges

Break-off of particles after crack spread toward the workpiece surface

Crack spread through thermal stresses due to temperature gradients

Induction of deep-lying cracks Blistering of ceramic particles after crack spread toward the workpiece surface

Tertiary MechanismsThermal StressCrack stopping effects at thermally plastified grain boundary phases Crack diversion at partially plastified grain boundary conditions in surface-near areas



The mode, size, and shape of the subsurface microcrack system depend on the induced contactstresses during the engagement of the abrasive grain. The contact stress field is basically determinedby the geometry of the indenter and the modulus of elasticity, hardness, and fracture toughness ofthe indenter and the workpiece material [Lawn 1993]. In the case of monocrystal silicon asworkpiece material, the anisotropy of these properties, as well as the position of the slip system,is also decisive. The formation of such microcrack systems was frequently investigated in analogytests with several brittle-hard materials such as silicon [Cook and Pharr 1990, Holz 1994].

The transition of elastoductile to mainly brittle surface formation can be classified into fourdifferent scratching morphologies (Figure 3.15). The individual areas of the scratches were iden-tified and marked under the microscope. To provide a three-dimensional image, the transition areasbetween the areas of different scratch morphologies were measured at a length of 1 mm. Then thescratch depths were determined on the individual profiles.

Knowing the material removal mechanisms during the machining of silicon, it is possible to realizea damage-poor process with the adequate settings and tools during the grinding of semiconductors.

FIGURE 3.14 Theoretical prerequisites for ductile grinding of optical glass. (From Koch 1991. With permission.)

Diamond grain Bond

Workpiece

Grain bondprotrusion

Shell crack

Depth crack

Pointed grain andexcess of the critical

chipping depth causebrittle fracture

Flattened grain andexcess of the critical

chipping depth causebrittle fracture

Flattened grain andexcess of the criticalchipping depth allow

ductile cutting

Depth crack

Shell crackWorkpiece

Workpiece

Bond

Bond

Diamond grain

Diamond grain

Cuttingspace

Displacedmaterial



Critical chippingdepth

Critical chippingdepth

Cutting depth

Criticalchipping depth


40H

and

bo

ok o

f Mach

inin

g with

Grin

din

g Wh

eels

FIGURE 3.15 Classification of scratch marks in four morphological zones and three transition areas characterizing the change from purely ductile to mainly brittlesurface formation.

Zone 1:Purely ductile materialremoval

Zone 2:Mainly ductile materialremoval, first cracksemerge in the bottom ofthe scratch

Zone 3:Increasingly brittlematerial removal, firstcracks on scratch bordersthat extend into thesurrounding material

Zone 4:Mainly brittle materialremoval, induced cracksinterlink and cause shell-like chippings

Transition area 1 Transition area 2 Transition area 3

Z (µm)

2.50

1.25

0.00

−1.25

−2.500 .88

0.69

0.50

0.31

0.12 0.37

0.44

0.50

0.570.64

Y(mm)X(nm)

0 Grad

Z (µm)

2.50

1.25

0.00

−1.25

−2.500 .81

0.62

0.43

0.25

0.06 0.370.43

0.49

0.55

0.61

Y(mm)X(nm)

Z (µm)

5.00

2.50

0.00

−2.50

−5.000 .84

0.65

0.46

0.27

0.08 0.390.46

0.52

0.59

0.66

Y(mm)X(nm)



This damage-poor grinding process is necessary to shorten the whole process chain and to decreasemachining costs.

3.8 ENERGY TRANSFORMATION

Mechanical energy is introduced into the grinding process by relative movement between the tooland the workpiece (Figure 3.16). This energy is mainly transformed into heat in an energy transfor-mation process, leading to temperature increase in the contact zone. The transformation of mechanicalenergy into thermal energy takes place through friction and deformation processes [Grof 1977,Lowin 1980]. External friction processes between abrasive grain and workpiece surface as well asbetween chip and abrasive grain are partly responsible for the heat development during grinding.However, heat also develops as a result of internal friction through displacement processes andplastic deformations [Grof 1977, Lowin 1980, Marinescu et al. 2004].

Heat development and heat flow during the grinding of brittle-hard materials differ decisivelyfrom the process in the machining of ductile materials (Figure 3.17). Heat development in the caseof ceramics has been investigated in many studies. Due to the relatively poor heat conductivity ofceramics and, in contrast, to a very high heat conductivity of diamond as a grinding agent, a bigpercentage of the heat flow to the tool and a considerably smaller heat flow to the workpiece wasobserved [Wobker 1992, Uhlmann 1994].

The following energy transformation processes occur during the grinding of ceramics [Uhlmann1994]:

• Energy from retained dislocations (plastic surface areas) after particle removal• Deformation energy at the workpiece surface (plastic scratch marks with a bulging at

the edge)• Elastic excess energy from the extension of existing microcracks during particle removal• Elastic energy from microscopic surface areas returning in the initial position• Friction work between diamond cutting edge and workpiece surface

FIGURE 3.16 Heat flow during the grinding of metallic materials. (From Koenig and Klocke 1996. With permission.)

Grinding wheel

Chip

Chip surfacefrictionEnvironment

(cooling lubricant, air)

ve

Flank frictionShear energy

Extrusion energy

Tool

Cutting edgeγα

Bond



• Friction work between ceramic particles (workpiece surface as well as ceramic particles)and diamond cutting edge

• Friction work between bond and workpiece surface

The use of cooling lubricant influences the heat development and the heat flow. The lubricantreduces the friction between the active partners entailing smaller heat development. The coolingmainly takes place through the water ratio in the cooling lubricant. Through the cooling effect, thepercentage of conducted heat increases.

REFERENCES

Bifano, T. et al. 1987. “Precision Machining of Ceramic Materials, Vortrag anläßl.” Intersociety Symposiumon Machining of Advanced Ceramic Materials and Components, Westerville, OH.

Bohlheim, W. 1995. “Verfahren zur Charakterisierung der Topografie von Diamantschleifscheiben.” IDR 29, 2.Bouzakis, K.-D. and Karachaliou, C. 1988. “Erfassung der Spanungsgeometrie und der Zerspankraftkompo-

nenten beim Flachschleifen aufgrund einer Dreidimensionalen Beschreibung der Schleifscheibento-pomorphie.” Fortschr.-Ber. VDI Reihe 2 Nr. 165, VDI, Düsseldorf.

Brinksmeier, E., Preuß, W., Riemer, O., and Malz, R. 1988. “Ductile to Brittle Transition Investigated byPlunge-Cut Experiments in Monocrystalline Silicon.” Proceedings of the ASPE Spring Topical Meet-ing on Silicon Machining.

Bruecher, T. 1996. “Kühlschmierung beim Schleifen keramischer Werkstoffe.” Ph.D. dissertation, TechnischeUniversität, Berlin.

Buettner, A. 1968. “Das Schleifen sprödharter Werkstoffe mit Diamant-Topfscheiben unter besonderer Berück-sichtigung des Tiefschleifens.” Dr. Ing. dissertation, Technische Universität, Hannover.

Cook, R. F. and Pharr, G. M. 1990. “Direct Observation and Analysis of Indentation Cracking in Glasses andCeramics.” J. Am. Ceram. Soc. 73, 4.

Damlos, H.-H. 1985. “Prozessablauf und Schleifergebnisse beim Tief- und Pendelschleifen von Profilen.”Fortschr.-Ber. VDI, Reihe 2, Nr. 88, VDI-Verlag, Düsseldorf.

Daude, O. 1966. Untersuchung des Schleifprozesses. Dr. Ing. dissertation, RWTH, Aachen.

FIGURE 3.17 Heat flow during the grinding of ceramics. (From Uhlmann 1994. With permission.)

Diamond grain

Ceramics

BondfrictionGrain friction

(external friction)

Bond

Plastic deformation(internal friction)

Heat flow towardsDiamond grainCeramic workpieceBondEnvironment

vc



Dennis, P. and van Schmieden, W. 1989. “Abdruckverfahren zur Dokumentation von Verschleißvorgängen.”VDI-Z 131, 1, S, 72–75.

Fruehling, R. 1976. “Topographische Gestalt des Schleifscheiben-Schneidenraumes und Werkstückrauhtiefebeim Außenrund-Einstechschleifen.” Dr. Ing. dissertation, TU Braunschweig.

Gaertner, W. 1982. “Untersuchungen zum Abrichten von Diamant- und Bornitridschleifscheiben.” Dr. Ing.dissertation, Technische Universität Hannover.

Grof, H. E. 1977. “Beitrag zur Klärung des Trennvorgangs beim Schleifen von Metallen.” Dr. Ing. dissertation,TU München.

Holz, B. 1994. “Oberflächenqualität und Randzonenbeeinflussung beim Planschleifen einkristalliner Silici-umscheiben.” Produktionstechnik – Berlin, Forschungsberichte für die Praxis, Bd. 143, Hrsg.: Prof.Dr. H. C. Mult. Dr. Ing, G. Spur. München, Wien, Hanser.

Hughes, F. H. 1974. “Wärme im Schleifprozess – ein Vergleich zwischen Diamant- und konventionellenSchleifmitteln.” IDR 8, 2.

Inasaki, C., Chen, C., and Jung, Y. 1989. “Surface, Cylindrical and Internal Grinding of Advanced Ceramics.Grinding Fundamentals and Applications.” Trans. ASME 39, S, 201–211.

Jacobs, U. 1980. “Beitrag zum Einsatz von Schleifscheiben mit kubisch-kristallinem Bornitrid als Schneidst-off.” Dr. Ing. dissertation, TU Braunschweig.

Kaiser, M. 1977. “Tiefschleifen von Hartmetall.” Fertigungstechnische Berichte, Bd. 9, Hrsg.: H. K. Tönshoff,Gräfelfing, Resch.

Karatzoglou, K. 1973. “Auswirkungen der Schneidflächenbeschaffenheit und der Einstellbedingungen auf dasSchleifergebnis beim Flach-Einstechschleifen.” Dr. Ing. dissertation, TU Braunschweig.

Kassen, G. 1969. “Beschreibung der elementaren Kinematik des Schleifvorganges.” Dissertation, RWTH,Aachen.

Kerstan, M., Ehlert, A., Huber, A., Helmreich, D., Beinert, J., and Doell, W. 1998. “Ultraprecision Grindingand Single Point Diamond Turning of Silicon Wafers and Their Characterisation.” Proceedings of theASPE Spring Topical Meeting on Silicon Machining, Camel-by-the-Sea, CA.

Klocke, F., Gerent, O., and Pähler, D. 2000. “Effiziente Prozesskette zur Waferfertigung.” ZwF 95, 3.Koch, E. N. 1991. “Technologie zum Schleifen asphärischer optischer Linsen.” Dissertation, RWTH, Aachen.Koenig, W., Steffens, K., and Yegenoglu, K. 1981. “Modellversuche zur Erfassung der Wechselwirkung

zwischen Reibbedingungen und Stofffluss.” Industrie Anzeiger. 103, 35.Koenig, W. and Klocke, F. 1996. Fertigungsverfahren Band 2. Schleifen, Honen, Läppen. 3. Auflage, VDI-

Verlag GmbH, Düsseldorf.Komanduri, R. and Ramamohan, T. R. 1994. “On the Mechanisms of Material Removal in Fine Grinding and

Polishing of Advanced Ceramics and Glasses, in Advancement of Intelligence Production. The JapanSociety for Precision Engineering, Elsevier Science, Amsterdam.

Kurrein, M. 1927. “Die Bearbeitbarkeit der Metalle im Zusammenhang mit der Festigkeitsprüfung.” Werk-stattstechnik. 21, S, 612–621.

Lawn, B. and Wilshaw, R. 1975. “Review Indentation Fracture: Principles and Applications.” J. Mat. Sci. 10.Lawn, B. 1993. Fracture of Brittle Solids, 2nd ed., Cambridge University Press, New York.Lehnicke, S. 1999. Rotationsschleifen von Silizium-Wafern. Fortschritt-Berichte VDI, Reihe 2, Nr. 534, VDI-

Verlag, Düsseldorf.Lierath, F., Jankowski, R., Schnekel, S., and Bage, T. 1990. “Prozessmodelle zur Qualitätssteigerung von Arbeit-

sabläufen in der Feinbearbeitung.” Tagungsband zum 6, Intern. Braunschweiger Feinbearbeitungskolloquium.Lortz, W. 1975. “Schleifscheibentopographie und Spanbildungsmechanismus beim Schleifen.” Dr. Ing. dis-

sertation, RWTH, Aachen.Lowin, R. 1980. “Schleiftemperaturen und ihre Auswirkungen im Werkstück.” Dissertation, RWTH, Aachen.Malyshev, V., Levin, B., and Kovalev, A. 1990. Grinding with Ultrasonic Cleaning and Dressing of Abrasive

Wheels. 61, 9, Stanki I Instrument, Moscow 22–26.Marinescu, I. D., Rowe, W. B., Dimitrov, B., and Inasaki, I. 2004. Tribology of Abrasive Machining Processes.

William Andrew Publishing, Norwich, NY.Menz, C. 1997. Randzonenanalyse bearbeiteter Siliziumoberflächen. Randzonenanalyse bearbeiteter Silizium-

Oberflächen. Fortschritt-Berichte VDI, Reihe 2, Nr. 431, VDI-Verlag, Düsseldorf.Nakayama, K. 1973. “Taper Print Method for the Measurement of Grinding Wheel Surface.” Bull. Japan Soc.

Prec. Eng. 7, 2.Pahlitzsch, G. and Helmerdig, H. 1943. “Bestimmung und Bedeutung der Spandicke beim Schleifen.”

Werkstattstechnik. 11/12, S, 397–399.



Paulmann, R. 1990. “Grundlagen zu einem Verfahrensvergleich.” Jahrbuch Schleifen, Honen, Läppen undPolieren. 56, Ausgabe, Vulkann-Verlag, Essen.

Reichenbach, G. S., Mayer, I. E., Kalpakcioglu, S., and Shaw, M. C. 1956. “The Role of Chip Thickness inGrinding. Trans. ASME 18, S, 847–850.

Rohde, G. 1985. “Beitrag zum Verhalten von keramisch-gebundenen Schleifscheiben im Abricht- und Schleifprozess.”Dr. Ing. dissertation, TU Braunschweig.

Roth, P. 1995. Abtrennmechanismen beim Schleifen von Aluminiumoxidkeramik. Fortschr.-Ber. VDI, Reihe 2,Nr. 335, VDI-Verlag, Düsseldorf.

Saljé, E. 1975. “Die Wirkrauhtiefe als Kenngröße des Schleifprozesses.” Jahrbuch der Schleif-, Hon-, Läpp- undPoliertechnik und der Oberflächenbearbeitung, 47, Ausgabe, Vulkan, Essen, S, 23–35.

Saljé, E. and Moehlen, H. 1987. “Prozessoptimierung beim Schleifen keramischer Werkstoffe, IndustrieDiamanten Rundschau.” IDR 21, 4.

Sawluk, W. 1964. “Flachschleifen von oxydkeramischen Werkstoffen mit Diamant-Topfscheiben.” Disserta-tion, Technische Hochschule Braunschweig.

Schleich, H. 1982. “Schärfen von Bornitridschleifscheiben.” Dr. Ing. dissertation, RWTH, Aachen.Shaw, M. C. and Komanduri, R. 1977. “The Role of Stylus Curvature in Grinding Wheel Surface Character-

ization. Ann. CIRP 25, 1.Shaw, M. C. 1995. “Cutting and Grinding of Difficult Materials.” Technical paper presented at the Abrasive

Engineering Society, Ceramic Industry Manufacturing Conference and Exposition, Pittsburgh, PA.Steffens, K. 1983. Thermomechanik des Schleifens. Fortschr.-Ber, VDI, Reihe 2, Nr. 65, VDI-Verlag, Düsseldorf.Stuckenholz, B. 1988. “Das Abrichten von CBN-Schleifscheiben mit kleinen Abrichtzustellungen.” Dr. Ing.

dissertation, RWTH, Aachen.Toenshoff, H. K., Peters, J., Inasaki, I., and Paul, T. 1992. “Modelling and Simulation of Grinding Processes.”

Ann. CIRP 41, 2, 677–688.Tönshoff, H. K. and Lehnicke, S. 1999. “Subsurface Damage Reduction of Ground Silicon Wafers.” Proceed-

ings of Euspen, Bremen, Germany.Treffert, C. 1995. “Hochgeschwindigkeitsschleifen mit galvanisch gebundenen CBN-Schleifscheiben.” Ber-

ichte aus der Produktionstechnik, Bd. 4/95, Aachen, Shaker.Tricard, M., Kassir, S., Herron, P., and Pei, Z. J. 1998. “New Abrasive Trends in Manufacturing of Silicon

Wafers.” Proceedings of the ASPE Annual Meeting, Indianapolis, IN.Uhlmann, E. 1994. “Tiefschleifen hochfester keramischer Werkstoffe.” Produktionstech—Berlin, Forschungsber.

für die Praxis, Bd. 129, Hrsg.: Prof. Dr. H. C. Mult. Dr. Ing. G. Spur, München, Wien, Hanser.Verkerk, J. 1977. “Final Report Concerning CIRP Cooperative Work on the Characterization of Grinding

Wheel Topography.” Ann. CIRP 26, 2.Vits, R. 1985. “Technologische Aspekte der Kühlschmierung beim Schleifen.” Dr. Ing. dissertation, RWTH, Aachen.Warnecke, G. and Spiegel, P. 1990. “Abrichten kunstharzgebundener CBN- und Diamantschleifscheiben.” IDR

24, 4, S, 229–235.Weinert, K. 1976. “Die zeitliche Änderung des Schleifscheibenzustandes beim Außenrund-Einstechschleifen.”

Dr. Ing. dissertation, TU Braunschweig.Werner, F. 1994. Hochgeschwindigkeitstriangulation zur Verschleißdiagnose an Schleifwerkzeugen. Fortschr.-Ber.

VDI, Reihe 8, Nr. 429, VDI-Verlag, Düsseldorf.Werner, G. 1971. “Kinematik und Mechanik des Schleifprozesses.” Dissertation RWTH, Aachen.Werner, G. and Kenter, M. 1987. “Work Material Removal and Wheel Wear Mechanisms in Grinding of

Polycrystalline Diamond Compacts.” Vortrag anläßl. Intersociety Symposium on Machining ofAdvanced Ceramic Materials and Components, Westerville, OH.

Wobker, H. G. 1992. Schleifen keramischer Schneidstoffe. Fortschr.-Ber. VDI, Reihe 2, Nr. 237, VDI-Verlag,Düsseldorf.

Zum Gar, K.-H. 1987. “Grundlagen des Verschleißes.” VDI Berichte Nr. 600.3: Metallische und NichtmetallischeWerkstoffe und ihre Verarbeitungsverfahren im Vergleich, VDI-Verlag, Düsseldorf.


chapter 3 material removal mechanisms

Documents

singular cutting edges

grinding process

case of grinding

single cutting edgescan

consequent removal mechanisms

grinding wheels thermal

basic mechanisms

surface formation