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
8
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
40
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
