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Abrasives & Abrasive Wheels

Their Nature, Manufacture and Use



A COMPLETE TREATISE ON

THE MANUFACTURE AND PRACTICAL USE OF
ABRASIVES, ABRASIVE WHEELS AND GRINDING OPERATIONS

INCLUDING

NATURAL AND ARTIFICIAL ABRASIVES, PRODUCTION AND PREP-
ARATION OF ABRASIVES, GRITS, GRADES AND BONDS, SHARPEN-
ING AND GRINDING STONES AND WHEELS, TESTING WHEELS
FOR EFFICIENCY, TRUING, REBUSHING AND INSTALLING
WHEELS, SAFETY DEVICES, AND DUST-COLLECTING SYSTEMS,
COMPLETE EXPOSITION ON SURFACE, EXTERNAL AND INTERNAL
GRINDING AND COMPREHENSIVE DATA COVERING THE PHYS-
ICAL AND CHEMICAL NATURE OF ABRASIVES IN GENERAL

BY

FRED B. JACOBS




A PRACTICAL HANDBOOK FOR ENGINEERS, FACTORY SUPERINTEN-
DENTS, FOUNDRYMEN, SHOP FOREMEN AND MECHANICS IN GENERAL

FULLY ILLUSTRATED



New York

The Norman W. Henley Publishing Company

2 West 45th Street

1919



Copyrighted, 1919, by
The Norman W. Henley Publishing Company



Printed in U. S. A.



Printing Presswork and Binding by
Harper & Brothers, New York






PREFACE

THE art of finishing metals by abrasion is one of the
oldest mechanical practices in existence, dating from
the time prehistoric man discovered that he could fashion
his wood and bone implements by rubbing them on rocks of a
gritty nature.

The grindstone is, without doubt, the oldest form of
grinding wheel known. With the early development of
the mechanical arts, it was discovered that a sandstone cut
in circular shape and mounted upon a revolving shaft,
showed higher efficiency than the side of a rock for sharpen-
ing and shaping various implements. It is definitely known
that grindstones, rotated by power, were used in the manu-
facture of armor as early as the year 1570. It is also
known that the emery deposits of the Grecian Archipelago
were known to the ancients and the value of this abrasive
recognized, as many writers of early days referred to emery
under various names. In considering some of the mechan-
ical achievements of the handicraftsmen who worked with
metals centuries before the Christian era, it is hard to
conceive how they attained so high a degree of perfection
without the use of an alumina abrasive for tool-sharpening
purposes.

While the practice of fashioning tools and implements by
abrasion is in all probability as old as civilization itself,
modern grinding, as we accept this term, is a compara-
tively recent development. About half a century ago,
the individual workman made his own grinding wheels of
glue and emery.

The first attempt at precision grinding consisted of finish-
ing the chilled iron calender rolls used in the paper-making

5



PREFACE

industry. Owing to the hard nature of the material in
question, it was a long and tedious process to turn these
rolls accurately.

The development of the sewing-machine industry in the
New England States gave impetus to the development of
the grinding-wheel business. As a matter of fact, the first
attempts at cylindrical grinding, aside from roll grinding,
consisted of finishing parts of the Wilcox & Gibbs sewing
machine. The work was done by the Brown & Sharpe
Mfg. Co.

With the advent of the automobile industry, over twenty
years ago, the grinding-wheel business received a fresh
impetus as a rapid means was in demand for the accurate
finishing of parts.

Today, the modern grinding wheel is among the most
useful of modern shop accessories. Without it, it would be
impossible to maintain the present-day standard of rapid
production. In practically every line of metal working,
the grinding wheel plays an important part, its usefulness
ranging all the way from the rough grinding of castings and
forgings to the finishing of accurate surfaces, both plane and
cylindrical.

In presenting this work, the writer has taken great
precaution to make sure that every statement is authentic.
Aside from knowledge gained through many years as a
journeyman machinist, later supplemented with several
years' experience as a grinding-wheel salesman, many months
were spent in collecting data, verifying statements and
consulting reliable authorities, both in this country and
abroad.

The writer is indebted to the following manufacturers
and individuals who cheerfully answered numerous letters
and supplied valuable data and photographs:

Abrasive Co. The Carborundum Co.

American Emery Wheel Works Chicago Wheel & Mfg. Co.

The Blanchard Machine Co. The Cincinnati Milling Machine

Brown & Sharpe Mfg. Co. Co.

6



PREFACE



The Cleveland Stone Co.
Cortland Grinding Wheel Corp.
Detroit Grinding Wheel Co.
Diamond Machine Co.
Parrel Foundry & Machine Co.
Metal & Thermit Corp.
H. G. Hammett.
Hampden Corundum Wheel Co.
The Heald Machine Co.
Frederick S. Jacobs, data on axe-
grinding. '
Landis Tool Co.

Manufacturers Corundum Co., Ltd.
Minnesota Mining & Mfg. Co.
Newton Machine Tool Works.
Norton Co.



Norton Grinding Co.

Penton Publishing Co.

Pittsburgh Crushed Steel Co.

Pratt & Whitney Co.

Fred E. Rogers, editor emeritus of

Machinery.

Safety Emery Wheel Works.
Springfield Grinding Co.
Springfield Mfg. Co.
Sterling Grinding Wheel Co.
B. F. Sturtevant Co.
Superior Corundum Wheel Co.
United States Geological Survey.
Vitrified Wheel Co.
Waltham Grinding Wheel Co.
Wardwell Mfg. Co.



Permission to reprint material by the writer which had
been previously published, was granted by the following
publishers :

Penton Publishing Co., Marine Review.
McGraw Hill Co., American Machinist.
S. S. Smith Co., The Woodworker.
W. R. C Smith Publishing Co., Iron Tradesman.
Iron Age Co., The Iron Age.

The MacLean Publishing Co., Ltd., Canadian Machinery.
The Mines Publishing Co., Ltd., publishers of The Canadian Mining
Journal, gave permission to reprint material concerning corundum.



FRED B. JACOBS.



June, 1919.



CONTENTS

CHAP. PAGE

PREFACE ix

I. NATURAL ABRASIVE SUBSTANCES Pages 13 to 36

Nature of natural abrasives Where found History of natural
abrasives Commercial application Sandstone Emery Corun-
dum Garnet Diamond Bort diamond Flint Quartz Nat-
ural sharpening stones Arkansas Washita Hindustan Tripoli

Pumice.

II. ARTIFICIAL ABRASIVES Pages 37 to 64

Various artificial abrasives Their physical and chemical properties

Their Commercial application Methods and processes employed
in the production of artificial abrasives Carborundum Alundum
Aloxite Boro- C arbone Oxalumina Adamite Crystolon, etc.
Relative hardness and abrasive efficiency of various materials
Artificial production of precious stones Their abrasive properties
Other artificial abrasives and their production Experimental
work Electro-thermic processes Production of rouge and crocus
Diamonds and crushed steel Angular grit.

III. THE MANUFACTURE OF GRINDING WHEELS .... Pages 65 to 82
Composition of grinding wheels Desirable and undesirable proper-
ties Bonds Shellac Rubber Fusible clays Silicate of soda
Vitrified wheels Method of oroducing vitrified wheels Puddled
process Pressed process Silicate wheels Shellac wheels Rubber
wheels Clay bond used in vitrified wheels Choice of bonding ma-
terial Wheel-turning Kiln used Heating of kiln and work
Cooling of kiln Dressing wheels Bushing wheels Speed tests for
wheels Elastic process Rubber process.

IV. ARTIFICIAL SHARPENING STONES Pages 83 to 87

Properties of artificial stones Carborundum stones Method of
manufacture Bond Grit Grade Finishing Combination
stones Carborundum rubs.

V. GRITS AND GRADES . . . ; Pages 88 to 96

Designation of grits and grades Mixed grits Grits of abrasive s
papers Standard grades Wheels Relation of speed to grade and

grit Wheel speeds for various operations.
9



CONTENTS

CHAP.

VI. TESTING WHEELS FOR EFFICIENCY Pages 97 to 114

Selection of wheels Improper methods of testing Practical testing
methods Items to be noted in a wheel test How to figure result
Formula for finding volume of abrasive material in a wheel General
considerations Wheel tests.

VII. LABORATORY TESTS Pages 115 to 122

Apparatus and appliances used Limitations of laboratory tests
Factors to be considered Laboratory testing machine Data for

test Work used in testing.

VIII. GRINDING WHEEL vs. GRINDSTONES Pages 123 to 128

Advantages of natural and artificial abrasive used in wheels Early

use of grindstones Special work where grindstones are still em-
ployed Action of grinding wheel.

IX. THE ECONOMIC ADVANTAGE OF USING LARGE WHEELS . Pages 129 to 132
Factors to be considered in choosing a wheel Comparative price of
wheels of various sizes Advantage of large wheels in certain work

Why large wheels are more efficient.

X. TRUING DEVICES FOR GRINDING WHEELS Pages 133 to 138

Abrasive action Tools used in truing wheels Use of bort and
carbonado diamonds in tools Getting stones in tool Procedure in
truing wheels.

XI. RE-BUSHING GRINDING WHEELS Pages 139 to 141

Methods used in bushing wheels Tools employed Metals used.

XII. SUGGESTIONS TO FOLLOW IN ORDERING GRINDING WHEELS

Pages 142 to 144

Information to be given with grinding-wheel order Factor govern-
ing selection of wheels How to determine what kind of a wheel
should be used Ordering special wheels.

XIII. DESIGN OF DUST-COLLECTING SYSTEMS .... Pages 145 to 150
State law requirments Design of wheel hood General design
Size of exhaust pipe for different size wheels Elbows Collars
Method of erection Clean-out Fan Dust-collector Exhaust
systems.

XIV. SAFEGUARDING GRINDING WHEELS Pages 151 to 165

Why wheels break Cause of accidents How wheels are packed

and tested before leaving factory Wheel speeds Mounting wheels
properly What causes wheels to burst Safety flanges Work rest
Wheel guards Grinding on small wheels Precautions for the
workman.

10



CONTENTS

CHAP.

XV. ABRASIVE PAPERS AND CLOTHS Pages 166 to 175

Abrasive substances used in making abrasive paper History of
abrasive paper How abrasive paper and cloth is manufactured
Grades of abrasive paper and cloth Finding percentage of iron in
garnet Testing garnet paper Paper and cloth abrasive discs -
Testing discs for efficiency.

XVI. SURFACE GRINDING Pages 176 to 215

Finishing work by surface grinding Development of the surface
grinding machine Finishing locomotive guide bars Rotary
grinding fixture Wheel speeds Cuts Die grinding How dies

are held Grinding punches Care of wheels Magnetic chucks
Demagnetizes Proper wheel selection for surface grinding Types
of surface-grinding machines Standard wheel list.

XVII. CYLINDRICAL GRINDING Pages 216 to 242

Cylindrical grinders Operation of grinders Driving devices for
work Proper wheel speeds for various metals and work Traverse
feed Depth of cut Roughing and finishing cuts Sparking
Backrest and steadyrests Lubrication of work Lubricating com
pounds and mixtures Dressing and truing wheels while on the
grinder Chatter marks and their remedy Selection of proper
wheels for use on cylindrical grinders Universal grinders Grinding
tapers Various operations on universal grinder.

XVIII. INTERNAL GRINDING Pages 243 to 262

Internal grinding machines Internal grinding on universal grinder

Setting up universal grinder for internal work Grinding double
tapers Automatic grinders Grinding holes in spur and bevel gears
Chucks Wet and dry grinding Proper speeds Selection of
wheels Operating of cylinder grinders Cylinder grinding.

XIX. SPECIAL GRINDING OPERATIONS Pages 263 to 289

Grinding calender rolls Special grinding machines Roll grinders

and roll grinding Corrugating flour-mill rolls Grinding crank-
shafts Grinding cam shafts Locomotive valve gears.

XX. CUTTER SHARPENING Pages 290 to 307

Machines employed for cutter grinding Adjustments and attach-
ments on cutter grinders Grinding spiral cutters General opera-
tion of cutter grinders Selection of wheels Speeds Depth of cut.

XXI. SAW SHARPENING Pages 308 to 321

Band saws and circular saws Operation of band-saw sharpening
machine Sharpening band saws Grinding in new teeth Care of
machine Selection of wheels for saw gumming Machines for
sharpening cold saws Sharpening hack-saw blades.

ii



CHAPTER ONE

NATURAL ABRASIVE SUBSTANCES

Nature of natural abrasives Where found History of natural abrasives
Commercial application Sandstone Emery Corundum Garnet
Diamond Bort diamond Flint Quartz Natural sharpening stones
Arkansas Washita Hindustan Tripoli Pumice.

NATURAL abrasives are being found in many parts of
the world. In a broad sense, the list includes all
minerals capable of abrasive action, but from a commercial
point of view, the principal natural abrasives are sandstone,
emery, corundum and garnet. The diamond is, of course,
a natural abrasive; indeed it is the hardest of all, but it is
needless to state that its rarity excludes it from the list of
commercial abrasive materials.

SANDSTONE

The first abrasive to be used in the form of a wheel was
in all probability sandstone. The use of a revolving stone
for sharpening purposes is so old that the beginning is
lost in antiquity. It seems reasonable to believe, however,
that the artificers of early civilization borrowed the idea
of a revolving sharpening stone from the crude mills used
many centuries ago for the grinding of grain.

Sandstone is a very curious mineral, indeed, as it consists
of uniform grains of sand (generally quartz with a small
percentage of feldspar and mica) firmly cemented together
with silica. Some varieties of sandstone, the Craigleith
stones used in the cut-glass industry for instance, are prac-
tically pure silica, this material often running as high as
98 per cent. Sandstone is found in many parts of the

13



ABRASIVES AND ABRASIVE WHEELS

world and in this country the most extensive deposits that
are worked for the production of grindstones are in Ohio
and Michigan. The Gray Canyon quarry at Amherst,
Ohio, is classed as the largest quarry in the world. Sand-
stones are of various colors, these being derived from
impurities that penetrated the mass during the formative
stage. Pure siliceous stones are white, or pale yellow in
cases where small quantities of iron oxide are present. A
red tinge is generally due to hematite, yellow to limonite,
green to glauconite, gray to clay and shale, and black, as
observed in black Graileith stones for example, to manganese
dioxide.

The average layman is of the opinion that all grindstones
are alike, but this supposition is erroneous for, in forming
the sandstone of which the grindstones of commerce are
made, it would appear that Nature anticipated the wants
of man by providing not only several grits to choose from,
but several grades as well. To insure an ample supply
of grits and grades, grindstone manufacturers generally
control holdings in various localities.

Before the advent of the grinding wheel, sandstone was
the only abrasive to be used in the form of a wheel. Its
use was, of course, limited, as practically the only grinding
done in the early manufacturing days consisted of tool
sharpening. Grindstones are used at present in large quan-
tities for sharpening edge tools, cutlery, etc., often in
preference to modern abrasive wheels. Many reasons for
this practice are explained later, under the heading, Grind-
stones Vs. Grinding Wheels.

EMERY

Emery, which in reality is an impure form of corundum,
has been known as an abrasive from very remote times. Its
value as an abrasive was known to the ancient Greeks/
Dioscorides referred to it as a stone used in gem engraving.
Emery was also known to the Romans, Pliny and other



EMERY

writers referring to it as naxium. There is also seme
authority for the statement that in the "adamant" of
the Old Testament, translated from the Hebrew, shamir
referred to emery ore. ^The principal emery deposits that
furnish the emery of commerce are located in Asia Minor,
in the basins of the Sarabat and Mender rivers. In the
Grecian Archipelago, the best known of these deposits are
located on the Island of Naxos, and in this country near
Chester, Mass., and Peekskill, N. Y.

Emery looks like iron ore, being of a dense, granular con-
struction. Its luster is metallic, while its color runs from
blue-black to black. It can truly be called a unique mineral,
as it is a mixture of alumina oxide and iron as magnetite
and hematite. At one time, all of the world's supply of
emery came from the Grecian Isles, principally Naxos, but
during the year 1847 Dr. J. Lawrence Smith located im-
portant emery deposits in Asia Minor. Dr. Smith's dis-
coveries proved to be of great benefit to the emery-consum-
ing trade owing to the fact that the price of emery was
materially reduced. Asia Minor or Turkish emery, as the
new material was called, at once became popular, as it
proved to be an efficient abrasive for many purposes.

Turkish emery always occurs in limestone or marble,
the deposits resting on gneiss, schist and mica slates, while
Naxos emery is generally found in limestone beds, being
associated with crystalline schists. One noticeable dif-
ference between the emery of the Grecian Archipelago and
that of Asia Minor is that in the former are numerous small
particles of mica which are seldom observed in the latter *-

The mining of both Turkish and Naxos emery is generally
carried on in a very primitive manner. Being near the sur-
face, the ore is easily removed as it is often present in loose
boulders. Masses that are too large for transportation to
the sea coast, are generally broken into fragments through
the process of heating them for a number of hours followed
by a sudden cooling with water. This causes the ore to
fracture in many places, and, by means of hammer blows, ^

15



ABRASIVES AND ABRASIVE WHEELS

it is an easy matter to reduce the ore to pieces suitable for
transportation. The low cost of mining, together with
moderate transportation costs, accounts for the fact that
Turkish emery finds a ready sale in this country in competi-
tion with American emery. For the purpose of grinding-
wheel manufacture, however, *&axos emery is considered
superior to all other kinds as it is the hardest, toughest
and most uniform. The foregoing sounds like a broad
statement, to be sure, but it is the consensus of opinion
expressed by leading grinding-wheel manufacturers who
make wheels of emery. L

The discovery of emery in this country dates back to
about the year 1830, at which time a railroad was being
built from Boston to the Hudson River. In making a cut
near Chester, Mass., a deposit of emery ore was uncovered,
which, at the time, was taken for iron ore. As previously
stated, emery and iron ore resemble each other closely.
Blast furnaces were erected and provision made for working
the ore on a moderately large scale. At the first attempt
to smelt the ore, however, great difficulties were encountered
in separating the iron from the alumina and the deposits
were ultimately condemned as too refractory for practical
purposes.

The mine remained idle and almost forgotten for a num-
ber of years. In 1864 or thereabout, Dr. H. S. Lucas,
realizing the possibilities of working the deposits as a source
of abrasive supply to compete with the foreign product,
bought the property and began to successfully operate it
as an emery mine. Operations have been continued in
this district until the present day. The emery in question
is associated with amphibolite and serpentine, and, as the
veins of ore reach several hundred feet underground, it is
necessary to work them by extensive tunneling.

Mention should also be made of the emery deposits in
New York state in the vicinity of Peekskill. rhis emery,
which is called a spinel emery, does not occur in a continu-
ous vein, but in segregated masses, being associated with

16



EMERY

morite rocks. In this ore spinel, which is magnesium
aluminate, MgAl 2 o 4 , furnishes the abrasive agent, since
spinel has a relative hardness of 8, as against 9, the hardness
of alumina, it is seen that spinel emery is somewhat softer
than other varieties of true emery. The value of spinel
emery should not be overlooked, however, as it furnishes
an efficient polishing material in cases where a very hard
and tough abrasive is not desired.

The specific gravity of emery varies in different speci-
mens from 3.7 to 4.3 and the percentage of alumina oxide
from 30 to 70. The abrasive power, sometimes called the
effective hardness, is not proportional to the amount of
alumina contained, being influenced to a great extent by
the proportions of other component parts in the form of
impurities such as silica, lime magnesia, etc., and the
structure of the grain itself. For the purpose of grinding-
wheel manufacture, the value of emery as an abrasive agent
is determined by the amount of alumina oxide present and
the toughness of the grain itself. ~^

In common with other natural products, emery ore
varies in' a number of characteristics. This is true not
only of specimens from different mines, but of the product
of one mine as well. To market a high-grade emery, it is
necessary to pay especial attention to the selection and
grading of the crude ore, to which end the use of the micro-
scope cannot be recommended too strongly, as by this
means more can be learned of the quality of the emery
than by resorting to any other method, aside from the
actual working test of the finished product.

As emery may have a high percentage of alumina and
at the same time the ore may be so constituted that, after
crushing, the grains will seem to possess no cutting points.
Such an emery does not make a very efficient grinding
wheel.

Some specimens of emery crush up into the proper kind
of grains, as far as cutting points are concerned, but at the
same time nothing but fine grains are produced. Again



ABRASIVES AND ABRASIVE WHEELS

it is sometimes noticed that small flakes of mica are
scattered through the ore, which is sure to cause trouble
in the vitrifying process if the emery is used in the
manufacture of vitrified grinding wheels. It is readily
seen that an efficient abrasive cannot be made of an
emery ore selected at random. It is of the utmost im-
portance to know the nature of the grain to adapt the
same for a given abrasive purpose.

At one time, all grinding wheels were made of emery.
Of late years, however, corundum and the different artificial
abrasives are used. At the same time, notwithstanding
the efficiency of modern abrasives, the more ancient emery
wheel still has its field of usefulness, and, strange as it may
seem, on some classes of grinding, steel castings and heavy
malleables, for instance, emery wheels continue to show
the highest efficiency. This statement is not made thought-
lessly, but is the result of several years of observation spent
in representing grinding-wheel manufacturers.

From a theoretical point of view, it would seem that
abrasives containing a higher percentage of alumina than
is present in emery, would prove more efficient, regardless
of the nature of the work. Actual tests, however, have
proven beyond a doubt that for certain purposes the emery
wheel is still in a position to successfully compete with
artificial abrasives. This is explained in a subsequent
chapter.

Again, emery wheels are comparatively low in price, and
they find a ready market among consumers whose grinding-
wheel wants are few. A manufacturer who uses grinding
wheels intermittently, a few minutes at a time, is not con-
cerned whether or not the wheel shows the highest efficiency.
As long as it gives satisfaction, within certain limits, no
good reason is see'n why a higher price should be paid for
a more improved abrasive.

Another factor, that should be mentioned while consid-
ering the emery wheel, is that owing to the high percentage
of oxide of iron contained, this abrasive, grit for grit, leaves

18



EMERY

a finer finish than any other abrasive material used in
grinding-wheel manufacture. Even on precision work, such
as gauge grinding and other similar operations, the emery
wheel still plays an important part and it is often the choice
of many engineers who know abrasives for their actual
worth.

Emery wheels, or emery stones, as they are termed in this
case, are also largely used for hulling oats and rice, taking
the place of the bed and runner natural stones as used in the
ordinary buhr mill. To whom the credit belongs for intro-
ducing the above stones, is not known for a certainty, but
experience has proven that the emery stone compares
favorably with the natural stones heretofore used for this
purpose.

Coarse emery is used in the form of bricks for rubbing



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