PRODUCT RANGE

2

CARBORUNDUM-DILUMIT has been active in the fi eld of

abrasive engineering and technology for over a century.

The foundation for further developments in abrasive

technology was laid around the year 1890, when the

engineer E. G. Acheson invented the fi rst synthetic

abrasive.

Made out of silicon carbide (SiC), he called this abrasive

“Carborundum”. Aluminium oxide (Al2O3), a further

synthetic grain, was developed a few years later. Both of

these abrasives are still in use around the world today,

and have made it possible to machine precision surfac-

es. Today, in the production of our abrasives, the use of

numerous new types of grain is taken for granted.

CARBORUNDUM-DILUMIT is one of the leading manu-

facturers of high quality grinding wheels and tools. Our

products proudly carry the “Made in Germany” seal,

with a number of production sites in Germany. We

focus all our efforts on meeting the requirements of this

seal of quality. We distribute our comprehensive product

line directly, or through exclusive partners in more than

150 countries worldwide.

CARBORUNDUM-DILUMIT is your trusted source for

grinding tools and abrasives in aluminium oxide, sin-

tered aluminium oxide, silicon carbide, diamond and

CBN. Our products are manufactured with resinoid,

vitrifi ed and rubber bonds in diverse compositions and

dimensions. We manufacture grinding wheels with

a diameter of up to 1,350 mm, and abrasives for all

existing machines and uses, whether precision grinding,

super precision grinding, form grinding, tool grinding

or roughing. The maximum working speed reaches

125 m/s for conventional and 140 m/s for CBN grinding

wheels.

Manufacturing technology as a key to success

Our method is to continually optimise our manufactur-

ing processes. Partnership is an active venture. By

partnership, we mean passing along know-how as well

as providing on-site consultations by our technical fi eld

agents and application engineers. Naturally, you can

expect service and prompt delivery from us. Our years

of experience in a wide range of grinding methods and

the close cooperation with various technical universities

and grinder manufacturers allow us to develop abrasive

products that match our clients’ needs. This enables us

to keep up with rising demands on performance and

quality, as well as to keep costs low.

CARBORUNDUM-DILUMITOur world is a disc.

It is our goal, as a leading technological supplier, to

consistently meet the ever-growing demands of our

customers. Regular internal audits of all departments of

our company ensure the high quality and precision

of our products.

With their dedicated commitment and their prepared-

ness for permanent further training, our highly qualifi ed

employees ensure that consistent high quality is main-

tained. All of our products undergo constant quality

control – from inspection of goods received to control of

production processes through to balance and strength

tests.

We are aware of the responsibility we bear for our

environment and therefore practice a policy of proactive

environmental protection. By conserving resources in the

production of abrasives and collecting and reprocessing

residues, we make an important contribution to the

maintenance and improvement of our environment.

To protect the health of our customers, we refrain

from using pollutant or potentially health-endangering

substances in our products. If you wish we are happy

to provide you with safety specifi cation sheets listing

ingredient substances for our products.

CONTENTS

2 CARBORUNDUM-DILUMIT

3 Quality and Environment Protection

4 Grinding Grain and Bonding

7 Product Range

8 Overview of the Main Grinding Processes

10 Criteria of Cut Value Optimisation

3

QUALITY AND ENVIRONMENT PROTECTION

4

THE BONDING SYSTEMS

The bonding – to put it simply – holds the individual

grinding grains together. The hardness of the grinding

material is determined by the selection of the bond

type and the percentage bonding proportion. With the

optimum design, the bonding should hold the individual

grains together, during the grinding process, as long as

they are sharp. Before they become blunt, the grinding

grains must break out of the grinding wheels.

CARBORUNDUM-DILUMIT manufactures grinding

wheels as vitrifi ed bond wheels, resinoid bond wheels

and rubberised bond wheels.

Vitrifi ed bonding

The chemical analysis of a vitrifi ed bond shows that

the composition is similar to that of glass and fi re-

resistant products. It consists of clay and feldspar.

Clay, as a ductile material, is a main component of

the ceramic bonding. With this property, they give

the necessary raw fracture strength. Feldspars are clay

silicates.

They function as a fl ux in vitrifi ed bonds, and thus

result in glazing of the bonding. The bond is melted

on during the fi ring process of the grinding wheels.

This results in the fi nal structure and property. The fi ring

temperatures for grinding wheels are between 900 °C

and 1300 °C. The fi ring continues for between 5 and 12

days, depending on the product. During the cooling for

several days, the bond solidifi es into glass. It envelops

the grinding grains and ensures the adhesion of the

grinding grains through bond webbing.

Vitrifi ed grinding wheels are chemically resistant to

the infl uence of grinding and have a high temperature

resistance. They are resistant to water and oil, but are

brittle and sensitive to impact.

Composition of grinding wheels

Conventional grinding materials

Hot-pressed grinding wheels

pore volume V

P

Conc

entra

tion

grai

n vo

lum

e V K

bonding volume VB

50

100

200

0

12100

40

50

68

100

55

40

0

100502550

GRINDING GRAIN AND BONDING

5

In many cases, the grain wear is the immediate cause

of the bond wear, because the fl attening of the grain

cutter causes, owing to the increased friction area,

a large increase in the cutting forces at the individual

grain and hence to a mechanical overloading of the

bond. Entire grains or grain groups can then break out

of the bond. These and other causes of wear are partic-

ularly important in the process design and especially in

the choice of the grinding wheel specifi cation, and are

given a great deal of consideration by CARBORUNDUM-

DILUMIT, and optimised for the respective application.

Resinoid bonding

Resinoid bonding involves condensed phenolic resins.

These bonds, existing on an organic base, are modifi ed

with different additive substances to achieve special

properties for a large number of grinding applications.

The grinding wheels are manufactured by cold pressing

followed by hardening in an electric furnace. The fi nal

hardening with maximum cross-linking is achieved at

170 °C to 190 °C. The exact selection of the fi nal tem-

perature changes the character of the bond into tough

or brittle. The hardness of the bond is controlled with

the percentage of resin.

Additional variants of the resinoid bonded products

are fi ller-free bonds. Some products are hot-pressed,

which result in an almost pore-free grinding tool.

Another variant of the organic bindings is the rubber

bonding of synthetic rubber.

For improving the strength of thick and hard grinding

wheels with high cutting speeds (63 and 80 m/s), they

are armoured with iron rings. Paper or plastic fl eece is

used in resinoid products with high working speeds

(80 and 100 m/s) (cut-off grinding wheels and compact

grinding wheels).

Organic bonds are temperature-resistant to a very small

extent. Resinoid bonds are more elastic than ceramic

bonds. However, they do not have the elasticity of

rubber bonds. Other positive aspects of resinoid bond

wheels are the non-sensitivity to shocks, impacts and

lateral pressure.

Grain and bonding wear

(Source: Manufacturing process, König/Klocke)

chemicaland thermalbonding wear

microcracks

grain fracturing

bond breakage

pressure softeningchemical wearmechanical abrasion

6

STRUCTURE OF THE GRINDING WHEELS

The structure is characterized by the ratio of grain

volume VK, bond volume VB and pore volume VP.

The indication of structure ranges from 0 through 20.

A closed structure is indicated by 0 and a very open

structure (highly porous) by 20. Here as well, no stand-

ard has yet been defi ned.

Structures 10 and above are referred to as porous

wheels. Burnout materials are used in the manufacture

of these wheels. The value to be determined through

volumetric modifi cation depends on the intended use.

Smaller pore spaces generally produce greater hard-

nesses, better edge conditions and smaller roughness

depths. At the same time, however, their capacity to

take up the chips to be removed declines. The risk of

thermal damage increases.

INFLUENCE OF THE BOND

The bonds have the job of holding the abrasive grain

until it is worn down by the cutting process. Once this

has occurred, they must release the grain so that the

sharp grains that succeed them are brought to bear. The

range of variation among the bonds used is very large.

The so-called self-sharpening effect is often sought.

Both inorganic and organic bonding agents are avail-

able. The majority of grinding wheels have vitrifi ed

bonds. They are the favoured choice for precision

grinding.

Vitrifi ed bonds have different characteristic features,

such as porcelain or glass-like structures.

Bond characteristics have been considerably improved in

recent years. In this way both greater wear resistance

and greater peripheral speed of the grinding wheel have

been achieved. The bonds were further developed

with respect to reproducibility as well. They aim for very

narrow manufacturing tolerances and low rejection

rates.

The important thing is the bond be matched to the

relevant machining conditions and the abrasive grain

used. The characteristics of vitrifi ed bonds may be

summarised as follows:

– brittle and therefore very sensitive to shock

– high elasticity modulus

– temperature resistant

– chemically resistant to coolants

Resinoid bonds are second in importance to the vitrifi ed

bond.

The principal application areas for resinoid bond grind-

ing wheels are snagging, polishing, cutting, roll grinding

and centerless grinding. Above all, the specifi c prop-

erties of the resinoid bonds consist in their relatively

unproblematic use with high peripheral speeds and in

cases where there are special requirements with respect

to insensitivity to shock or impact. The so-called self-

sharpening effect is also easier to achieve with these

bonds.

GRINDING GRAIN AND BONDING

7

CBN & diamond external cylindrical grinding wheels

Cut-off wheels

CBN & diamond lateral surface grinding wheels

Dressing tools

Conventional external cylindrical grinding wheels

Grinding cups

Conventional lateral surface grinding wheels

Centerless grinding wheels

Loose abrasive media

Grinding segments

Grinding segments

Control & transport wheels

Gear grinding wheels

Crankshaft grinding wheels

HP grinding wheels

Razor blade grinding wheels

Internal & external cylindrical grinding wheels

Special products

Lateral surface grinding wheels

Accessories

PRODUCT RANGE

8

CYLINDRICAL GRINDING

Cylindrical grinding is the most frequently used grinding

process. It is used to produce precise cylindrical work-

piece contours and to achieve high quality surface

fi nishes. It may be subdivided according to workpiece

supports and main feed directions into traverse, cross

and plunge grinding.

The principal distinctions are made between external

and internal cylindrical grinding along with, as variants,

plunge grinding, grinding between peaks and, as a

special process variant, centerless grinding, which, by

virtue of its special range of application, occupies a

special position. Because of the economic effi ciency and

optimal automation possibilities of centerless grinding,

it is used primarily in mass production.

CARBORUNDUM-DILUMIT produces grinding wheels for

cylindrical grinding with vitrifi ed, resinoid bonds and

rubber bonds.

FLAT GRINDING

Flat grinding as a rule is used to produce completely fl at

surfaces on workpieces. Several alternative methods

characterise fl at grinding. In the main, peripheral grind-

ing wheels, cup grinding wheels and grinding segments

are used.

Peripheral grinding wheels are favoured for the pro-

duction of grooves and profi les, where it is customary

to work with especially open porous grinding wheels

in both swing grinding and deep cutting.

Cup grinding wheels are used universally and are

customary for machining small surfaces.

Grinding segments represent an alternative to cup

grinding wheels or peripheral grinding wheels, when

these cannot be used because of their limited diameter.

But they are used even with smaller diameters by virtue

of their cool grinding. Their greatest advantage over

grinding cups and grinding wheels is their high material

removal rate.

CARBORUNDUM-DILUMIT produces grinding segments

in vitrifi ed and resinoid bonds. They are available in a

variety of forms and versions.

OVERVIEW OF THE MAIN GRINDING PROCESSES

9

ROLL GRINDING

Roll grinding is encountered principally in the steel,

aluminium foil and paper industries. It is set up accord-

ing to the manufacturer and driving powers of the

particular machines used. In general, grinding wheel

diameters from 600 to 1050 mm with a width of 65

to 150 mm are used.

The sometimes extremely high machining values for

the roughing of rolls, especially in the steel industry,

are characteristic of roll grinding. The aluminium and

paper industries make the greatest demands on the

quality of the rolls with respect to rotational motion,

parallelism and surface quality. Typical errors such as

comma marks, feed marks and chatter marks are not

allowed.

CARBORUNDUM-DILUMIT offers the grinding wheels

most often used for this purpose with resinoid bonds, as

well as grinding wheels with vitrifi ed bonds.

The use of CBN grinding wheels has increased recently.

Here also Carborundum Abrasives offers the right

selection in its production line; just ask us for our special

CBN brochure.

TOOTH FLANK GRINDING

The fi nishing of tooth fl anks represents a special

category of grinding. It is subdivided, according to its

process kinematics, into continuous generating grinding

and profi le grinding. Here the form of the involute must

be produced with a precisely profi led grinding wheel or

a relative motion between workpiece and tool. For this

purpose, we manufacture precision grinding wheels in

vitrifi ed bond that deliver good chip removal rates with-

out affecting the structure of the tooth fl anks.

Ground gear wheels are used primarily in automobile

and vehicle construction and in the construction of

industrial, maritime and wind power gear units. The

manufacture of gear unit components usually requires

a cylindrical grinding process, such as oblique plunge

grinding and groove grinding.

10

In the future, the trend in grinding technology will be

towards higher standards for workpiece quality in

conjunction with higher material removal rates during

the grinding process. To bring this development further,

it is indispensable that machining data, machines and

working materials be closely matched to one another

in connection with the grinding wheel.

In addition, the available performance capabilities of

the grinding machines are not fully used by the industry.

The economic effi ciency of the grinding process and

workpiece quality could in many cases be considerably

improved.

For the optimum choice of grinding wheel in relation to

a specifi c grinding task, it is imperative that the precise

relationships be recognized and considered.

These performance and limit criteria for the grinding

process must all be matched to the particular grinding

task at hand. They include, among other things, cutting

forces, surface quality, effects on peripheral zones,

material removal rates and the wear resistance factor.

Here are a few useful tips for users for optimising

cutting values for grinding processes.

Relationship between the input parameters

(Source: Manufacturing process, König/Klocke)

System

Machine- Type- Characteristics

Workpiece- Shape- Workpiece material

Grinding wheel- Shape- Composition

Dressing tool- Type

Cooling lubricant- Type- Delivery

Regulating variables

InfeedFeed rate

Workpiece speed

Cut speed

Dressing conditions

Infeed pressureFlow volume

- mechanical andthermic removalmechanisms

- chemical,mechanicaland thermalwear mechanisms

Process parameters

INPUT PARAMETERS GRINDING PROCESS RESULTS

Disturbance variable- Oscillation- Temperature

Technology

Workpiece- Form precise- Precise in

measurement- Precise in surface

Grinding wheel- Wear- Loading

Cooling lubricant- Contamination

Operating efficiency

Production numbers

- Surface zoneinfluence

CRITERIA OF CUT VALUE OPTIMISATION

11

THE MATERIAL TO BE WORKED

The optimal choice of grinding parameters is to a

considerable degree infl uenced by the grindability of the

available material. The chemical composition of the steel

and the alteration of its characteristics through heat

treatment are decisive factors in the grinding process.

They determine which grain type and which wheel hard-

ness must be selected.

Scientifi c research into machinability for grinding pur-

poses has made discoveries with respect to decomposit-

ion, bond fracturing, grain fracturing and abrasive grain

wear that are directly attributable to the material or the

material’s condition.

Materials such as aluminium and copper have a ten-

dency towards premature clogging of wheel pore space

through formation of chip coatings, thereby producing

considerable process disruptions. With respect to wheel

wear, these materials, due to their specifi c hardness, are

of no importance.

Tool steels and stainless steel types with high chrome

and nickel content are to be classifi ed as relatively

diffi cult to machine. Hard special carbides, some of

which are harder than pure aluminium oxide, form

during the grinding of hardened high-speed steels with

a high content of such alloys as vanadium, tungsten

and molybdenum. In this case high macro wear must

be expected. For these materials, only silicon carbide

and CBN are suitable as abrasive grains.

GRAIN SIZE

Grain size is determined by the desired surface quality

and the material removal rate aimed for.

As the grain size increases, the quantity of cutting edges

declines. This in turn leads to greater chip thicknesses.

The surface quality achieved declines at the same time.

The potential removal rate increases, however. For this

reason a rough grain is used for rough grinding. Finer

grains are used primarily in fi nish grinding. Each grain

size is thus assigned to a specifi c work category. Finer

grains are often added to coarse grains to achieve

greater wheel strength.

The fi ner grain has an added supporting effect, so that

edge wear also improves during profi le grinding.

The choice of grain sizes should be defi ned in such a

way that the desired surface is achieved with the largest

possible grain. In this way the maximum material

removal rate will be achieved. The cutting speed of the

grinding wheel and cooling are important in making

the right match. Even the dressing process is of great

importance in defi ning the grain.

As grinding wheel peripheral speed increases, the

cutting forces, the achievable surface roughness of

the workpiece and wear on the grinding wheel are

all lowered. At the same time, as grinding wheel

peripheral speed increases, the wheel life of the

grinding wheel can be increased.

GRINDING WHEEL HARDNESS

At this time there is no generally accepted standard

for hardness that would allow comparison between

grinding wheels of different manufacturers. The hard-

ness of a grinding wheel is indicated with the letters

from A to Z. A corresponds to the softest, Z to the

hardest grade.

The hardness of a wheel refers to the resistance to the

breaking off of blunted grains from the grinding wheel.

It is determined by the volumetric composition of grain,

bond and pore space and their distribution. Different

effective hardnesses are achieved through the most

varied bond types and characteristic properties in each

case.

Carborundum-Dilumit Schleiftechnik GmbH

Kappeler Straße 105 | 40597 Düsseldorf

Phone +49 (0) 211 . 74 93 - 235 | Fax +49 (0) 211 . 74 93 - 250

info@carborundum-dilumit.de

www.carborundum-dilumit.de

Mar

celli

ni M

edia

Gm

bH