PRODUCT RANGE - carborundum-schleifmittel.de

4 THE BONDING SYSTEMS The bonding – to put it simply – holds the individual grinding grains together. The hardness of the grinding material is determi...

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PRODUCT RANGE

CARBORUNDUM-DILUMIT Our world is a disc. CARBORUNDUM-DILUMIT has been active in the field of

CARBORUNDUM-DILUMIT is your trusted source for

abrasive engineering and technology for over a century.

grinding tools and abrasives in aluminium oxide, sin-

The foundation for further developments in abrasive

tered aluminium oxide, silicon carbide, diamond and

technology was laid around the year 1890, when the

CBN. Our products are manufactured with resinoid,

engineer E. G. Acheson invented the first synthetic

vitrified and rubber bonds in diverse compositions and

abrasive.

dimensions. We manufacture grinding wheels with

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

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

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

existing machines and uses, whether precision grinding,

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

super precision grinding, form grinding, tool grinding

these abrasives are still in use around the world today,

or roughing. The maximum working speed reaches

and have made it possible to machine precision surfac-

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

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

wheels.

numerous new types of grain is taken for granted. CARBORUNDUM-DILUMIT is one of the leading manu-

Manufacturing technology as a key to success

facturers of high quality grinding wheels and tools. Our

Our method is to continually optimise our manufactur-

products proudly carry the “Made in Germany” seal,

ing processes. Partnership is an active venture. By

with a number of production sites in Germany. We

partnership, we mean passing along know-how as well

focus all our efforts on meeting the requirements of this

as providing on-site consultations by our technical field

seal of quality. We distribute our comprehensive product

agents and application engineers. Naturally, you can

line directly, or through exclusive partners in more than

expect service and prompt delivery from us. Our years

150 countries worldwide.

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.

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QUALITY AND ENVIRONMENT PROTECTION

It is our goal, as a leading technological supplier, to consistently meet the ever-growing demands of our CONTENTS

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 preparedness for permanent further training, our highly qualified

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CARBORUNDUM-DILUMIT

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Quality and Environment Protection

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Grinding Grain and Bonding

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Product Range

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Overview of the Main Grinding Processes

employees ensure that consistent high quality is maintained. All of our products undergo constant quality control – from inspection of goods received to control of production processes through to balance and strength tests.

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Criteria of Cut Value Optimisation

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 specification sheets listing ingredient substances for our products.

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GRINDING GRAIN AND BONDING THE BONDING SYSTEMS

Vitrified bonding

The bonding – to put it simply – holds the individual

The chemical analysis of a vitrified bond shows that

grinding grains together. The hardness of the grinding

the composition is similar to that of glass and fire-

material is determined by the selection of the bond

resistant products. It consists of clay and feldspar.

type and the percentage bonding proportion. With the

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

optimum design, the bonding should hold the individual

the ceramic bonding. With this property, they give

grains together, during the grinding process, as long as

the necessary raw fracture strength. Feldspars are clay

they are sharp. Before they become blunt, the grinding

silicates.

grains must break out of the grinding wheels.

They function as a flux in vitrified bonds, and thus

CARBORUNDUM-DILUMIT manufactures grinding

result in glazing of the bonding. The bond is melted

wheels as vitrified bond wheels, resinoid bond wheels

on during the firing process of the grinding wheels.

and rubberised bond wheels.

This results in the final structure and property. The firing temperatures for grinding wheels are between 900 °C

50

and 1300 °C. The firing continues for between 5 and 12

Conventional grinding materials

days, depending on the product. During the cooling for

Hot-pressed grinding wheels

several days, the bond solidifies into glass. It envelops the grinding grains and ensures the adhesion of the

100 0

Co

nc

en

tra

tio

n

Composition of grinding wheels

grinding grains through bond webbing.

100 12

200

Vitrified grinding wheels are chemically resistant to the influence of grinding and have a high temperature

K

V in gra

68

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

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brittle and sensitive to impact.

e VP

vo lu

55

m olu

50

v re

me

po

40

100 0 0 5

4

25

50 bonding volume VB

100

Resinoid bonding

Grain and bonding wear

Resinoid bonding involves condensed phenolic resins. These bonds, existing on an organic base, are modified 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 final

chemical and thermal bonding wear

bond breakage grain fracturing

microcracks

hardening with maximum cross-linking is achieved at

pressure softening chemical wear mechanical abrasion

170 °C to 190 °C. The exact selection of the final temperature changes the character of the bond into tough or brittle. The hardness of the bond is controlled with the percentage of resin.

(Source: Manufacturing process, König/Klocke)

Additional variants of the resinoid bonded products are filler-free bonds. Some products are hot-pressed,

In many cases, the grain wear is the immediate cause

which result in an almost pore-free grinding tool.

of the bond wear, because the flattening of the grain

Another variant of the organic bindings is the rubber

cutter causes, owing to the increased friction area,

bonding of synthetic rubber.

a large increase in the cutting forces at the individual grain and hence to a mechanical overloading of the

For improving the strength of thick and hard grinding

bond. Entire grains or grain groups can then break out

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

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

are armoured with iron rings. Paper or plastic fleece is

ularly important in the process design and especially in

used in resinoid products with high working speeds

the choice of the grinding wheel specification, and are

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

given a great deal of consideration by CARBORUNDUM-

grinding wheels).

DILUMIT, and optimised for the respective application.

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.

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GRINDING GRAIN AND BONDING

STRUCTURE OF THE GRINDING WHEELS

Vitrified bonds have different characteristic features,

The structure is characterized by the ratio of grain

such as porcelain or glass-like structures.

volume VK, bond volume VB and pore volume VP. The indication of structure ranges from 0 through 20.

Bond characteristics have been considerably improved in

A closed structure is indicated by 0 and a very open

recent years. In this way both greater wear resistance

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

and greater peripheral speed of the grinding wheel have

ard has yet been defined.

been achieved. The bonds were further developed with respect to reproducibility as well. They aim for very

Structures 10 and above are referred to as porous

narrow manufacturing tolerances and low rejection

wheels. Burnout materials are used in the manufacture

rates.

of these wheels. The value to be determined through volumetric modification depends on the intended use.

The important thing is the bond be matched to the

Smaller pore spaces generally produce greater hard-

relevant machining conditions and the abrasive grain

nesses, better edge conditions and smaller roughness

used. The characteristics of vitrified bonds may be

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

summarised as follows:

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

– brittle and therefore very sensitive to shock – high elasticity modulus

INFLUENCE OF THE BOND

– temperature resistant

The bonds have the job of holding the abrasive grain

– chemically resistant to coolants

until it is worn down by the cutting process. Once this has occurred, they must release the grain so that the

Resinoid bonds are second in importance to the vitrified

sharp grains that succeed them are brought to bear. The

bond.

range of variation among the bonds used is very large. The principal application areas for resinoid bond grindThe so-called self-sharpening effect is often sought.

ing wheels are snagging, polishing, cutting, roll grinding

Both inorganic and organic bonding agents are avail-

and centerless grinding. Above all, the specific prop-

able. The majority of grinding wheels have vitrified

erties of the resinoid bonds consist in their relatively

bonds. They are the favoured choice for precision

unproblematic use with high peripheral speeds and in

grinding.

cases where there are special requirements with respect to insensitivity to shock or impact. The so-called selfsharpening effect is also easier to achieve with these bonds.

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PRODUCT RANGE

Internal & external cylindrical grinding wheels

CBN & diamond external cylindrical grinding wheels

Conventional external cylindrical grinding wheels

Centerless grinding wheels

Grinding segments

Gear grinding wheels

Crankshaft grinding wheels

HP grinding wheels

Razor blade grinding wheels

Lateral surface grinding wheels

CBN & diamond lateral surface grinding wheels

Conventional lateral surface grinding wheels

Grinding segments

Special products

Cut-off wheels

Grinding cups

Loose abrasive media

Control & transport wheels

Accessories

Dressing tools

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OVERVIEW OF THE MAIN GRINDING PROCESSES CYLINDRICAL GRINDING

FLAT GRINDING

Cylindrical grinding is the most frequently used grinding

Flat grinding as a rule is used to produce completely flat

process. It is used to produce precise cylindrical work-

surfaces on workpieces. Several alternative methods

piece contours and to achieve high quality surface

characterise flat grinding. In the main, peripheral grind-

finishes. It may be subdivided according to workpiece

ing wheels, cup grinding wheels and grinding segments

supports and main feed directions into traverse, cross

are used.

and plunge grinding. Peripheral grinding wheels are favoured for the proThe principal distinctions are made between external

duction of grooves and profiles, where it is customary

and internal cylindrical grinding along with, as variants,

to work with especially open porous grinding wheels

plunge grinding, grinding between peaks and, as a

in both swing grinding and deep cutting.

special process variant, centerless grinding, which, by virtue of its special range of application, occupies a

Cup grinding wheels are used universally and are

special position. Because of the economic efficiency and

customary for machining small surfaces.

optimal automation possibilities of centerless grinding, it is used primarily in mass production.

Grinding segments represent an alternative to cup grinding wheels or peripheral grinding wheels, when

CARBORUNDUM-DILUMIT produces grinding wheels for

these cannot be used because of their limited diameter.

cylindrical grinding with vitrified, resinoid bonds and

But they are used even with smaller diameters by virtue

rubber bonds.

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 vitrified and resinoid bonds. They are available in a variety of forms and versions.

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ROLL GRINDING

TOOTH FLANK GRINDING

Roll grinding is encountered principally in the steel,

The finishing of tooth flanks represents a special

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

category of grinding. It is subdivided, according to its

ing to the manufacturer and driving powers of the

process kinematics, into continuous generating grinding

particular machines used. In general, grinding wheel

and profile grinding. Here the form of the involute must

diameters from 600 to 1050 mm with a width of 65

be produced with a precisely profiled grinding wheel or

to 150 mm are used.

a relative motion between workpiece and tool. For this purpose, we manufacture precision grinding wheels in

The sometimes extremely high machining values for

vitrified bond that deliver good chip removal rates with-

the roughing of rolls, especially in the steel industry,

out affecting the structure of the tooth flanks.

are characteristic of roll grinding. The aluminium and paper industries make the greatest demands on the

Ground gear wheels are used primarily in automobile

quality of the rolls with respect to rotational motion,

and vehicle construction and in the construction of

parallelism and surface quality. Typical errors such as

industrial, maritime and wind power gear units. The

comma marks, feed marks and chatter marks are not

manufacture of gear unit components usually requires

allowed.

a cylindrical grinding process, such as oblique plunge grinding and groove grinding.

CARBORUNDUM-DILUMIT offers the grinding wheels most often used for this purpose with resinoid bonds, as well as grinding wheels with vitrified 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.

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CRITERIA OF CUT VALUE OPTIMISATION

In the future, the trend in grinding technology will be

For the optimum choice of grinding wheel in relation to

towards higher standards for workpiece quality in

a specific grinding task, it is imperative that the precise

conjunction with higher material removal rates during

relationships be recognized and considered.

the grinding process. To bring this development further, it is indispensable that machining data, machines and

These performance and limit criteria for the grinding

working materials be closely matched to one another

process must all be matched to the particular grinding

in connection with the grinding wheel.

task at hand. They include, among other things, cutting forces, surface quality, effects on peripheral zones,

In addition, the available performance capabilities of

material removal rates and the wear resistance factor.

the grinding machines are not fully used by the industry. The economic efficiency of the grinding process and

Here are a few useful tips for users for optimising

workpiece quality could in many cases be considerably

cutting values for grinding processes.

improved.

Relationship between the input parameters

INPUT PARAMETERS

RESULTS

System

Regulating variables

Process parameters

Technology

Machine - Type - Characteristics

Infeed Feed rate

- mechanical and thermic removal mechanisms

Workpiece - Shape - Workpiece material

Workpiece speed

- chemical, mechanical and thermal wear mechanisms

Workpiece - Form precise - Precise in measurement - Precise in surface - Surface zone influence

Grinding wheel - Shape - Composition

Cut speed

Grinding wheel - Wear - Loading Cooling lubricant - Contamination

Dressing tool - Type

Dressing conditions

Cooling lubricant - Type - Delivery

Infeed pressure Flow volume

(Source: Manufacturing process, König/Klocke)

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GRINDING PROCESS

Disturbance variable - Oscillation - Temperature

Operating efficiency Production numbers

THE MATERIAL TO BE WORKED The optimal choice of grinding parameters is to a

grains are often added to coarse grains to achieve

considerable degree influenced by the grindability of the

greater wheel strength.

available material. The chemical composition of the steel and the alteration of its characteristics through heat

The finer grain has an added supporting effect, so that

treatment are decisive factors in the grinding process.

edge wear also improves during profile grinding.

They determine which grain type and which wheel hardness must be selected.

The choice of grain sizes should be defined in such a way that the desired surface is achieved with the largest

Scientific research into machinability for grinding pur-

possible grain. In this way the maximum material

poses has made discoveries with respect to decomposit-

removal rate will be achieved. The cutting speed of the

ion, bond fracturing, grain fracturing and abrasive grain

grinding wheel and cooling are important in making

wear that are directly attributable to the material or the

the right match. Even the dressing process is of great

material’s condition.

importance in defining the grain.

Materials such as aluminium and copper have a ten-

As grinding wheel peripheral speed increases, the

dency towards premature clogging of wheel pore space

cutting forces, the achievable surface roughness of

through formation of chip coatings, thereby producing

the workpiece and wear on the grinding wheel are

considerable process disruptions. With respect to wheel

all lowered. At the same time, as grinding wheel

wear, these materials, due to their specific hardness, are

peripheral speed increases, the wheel life of the

of no importance.

grinding wheel can be increased.

Tool steels and stainless steel types with high chrome

GRINDING WHEEL HARDNESS

and nickel content are to be classified as relatively

At this time there is no generally accepted standard

difficult to machine. Hard special carbides, some of

for hardness that would allow comparison between

which are harder than pure aluminium oxide, form

grinding wheels of different manufacturers. The hard-

during the grinding of hardened high-speed steels with

ness of a grinding wheel is indicated with the letters

a high content of such alloys as vanadium, tungsten

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

and molybdenum. In this case high macro wear must

hardest grade.

be expected. For these materials, only silicon carbide and CBN are suitable as abrasive grains.

The hardness of a wheel refers to the resistance to the breaking off of blunted grains from the grinding wheel.

GRAIN SIZE

It is determined by the volumetric composition of grain,

Grain size is determined by the desired surface quality

bond and pore space and their distribution. Different

and the material removal rate aimed for.

effective hardnesses are achieved through the most varied bond types and characteristic properties in each

As the grain size increases, the quantity of cutting edges

case.

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 finish grinding. Each grain size is thus assigned to a specific work category. Finer

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Marcellini Media GmbH

Carborundum-Dilumit Schleiftechnik GmbH

Kappeler Straße 105 | 40597 Düsseldorf Phone +49 (0) 211 . 74 93 - 235 | Fax +49 (0) 211 . 74 93 - 250 [email protected] www.carborundum-dilumit.de