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TRANSCRIPT
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
www.carborundum-dilumit.de
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