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Patented Sept. 24, 1946
, UNITED _‘
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2,408,319
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_ 2,408,319".
I‘ ABnAsIvE Anrrcms
Samuel S. Kistler, West Boylston; ‘Mass, assign'oi‘
to Norton Company, Worcester, ‘Mass, a cor- .
po'ration of Massachusetts‘
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serial No. 643,202:
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5 Claims. (01-. 51-4367)‘
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' Application .ilanuary 24, (1948,
7 No Drawing».
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' ‘The f‘inventi‘on relates to abrasive \articleseind
more particularly to grinding. wheels.
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under the same conditions, one which gives a
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higher Q number where
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2
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One object of the invention is to provide an
active :?ller for grinding wheels and other abra
sive products, particulamy :ror organic bonded
products, which improves ‘the: quality thereof.
and which also has a higher ratio where
‘Another object o’f the invention is to provide ‘a
ratio-W
filler with a higher :quality number ‘Q where. .
" 10
is a superior ?ller for most dry snagging, opera
‘ions.
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In ‘accordance with my invention 1 have found
is a constant, M is material removed
that the quality and economy of abrasive articles,
and particularly grinding wheels,‘ may be mate
vention is to provide a ?ller which gives a higher
ratio of material removed to wheel wear. Other
objects will be in part obvious or in part vpointed
riially improved by incorporating therein the
where
and
is wheel wear. Another object of the in
combination of potassium ?uoborate ‘(~KBF4) and
iron sulphide such as troilliteiFeS) or pyrites
- and marcasite (FeSz). Each or these has pre
abrasive are assumed to cost likeamounts. ‘But
let us assume two wheels having, the same ratio
Ein ‘a given grinding job but where the ‘material
removed by wheel A in a given time ‘is twice-‘that
lviously been used. In :my Patent No. 323084981
there ‘is described and claimeda filler :of iron sul
L-phide. .Inmy Patent No. 2,308,983 there is de
scribed i'and claimed an alkali metal ?uoborate
speci?cally potassium ?uob‘orate. Of these, two
?llers ‘potassium ?uoborate was found to be
25. superior for most snagging ‘operations. ‘I; have
now made, the surprising discovery that the use
of :both. of these ?llers in combinationqgives bet
removed by wheel B in the same time. Clearly
wheel A is commercially preferable for SllChjOb
because the labor cost and overhead are half of
30 wheel wear than the use of'either of ‘them alone.
out'hereinafter.
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Efficiency of grinding’ wheels .hasisome'times in
the past been stated'in terms of ratioo'f “material
removed to wheel wear. This quite accurately
gives the economy of grinding so 'far as the cost
of abrasive ' is concerned, if like quantities of
ter grinding results as measured both: by quality
number Q and by ratio of material removed ‘to
This indicates that there may besome inter
action between the two compounds and iron or
that {for wheelB. 'No one formulaior determin
'ing the ‘most economical wheel under all: condi
steel beingground which. is different from the
‘tions of labor cost‘and'overhead can be devised.
‘It-happens, however, that the expression
M’
action of either of them on the iron or steelbe
Other
35 ingground or the sum of such actions.
wise it would seem to be clear that the mixture
of ‘the two ?llers would produce a result which ‘is
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' the mean of the results produced by these?llers
measures the economy ‘of grinding wheels in
many grinding operations providing ‘a large a1 40, The ‘?ller of the invention has been used in
grindingwheels for ‘snagging operations consist
.l'owance 'for labor cost ‘and also ‘for “overhead; It
“can be generalized that in most d-ry snagging
ing of fused ‘alumina abrasive bondedjwith phenol
formaldehyde ibond. The manufacture of such
"operations the true ‘economy is "an expression.
grinding wheels vis inowewe'll known‘and for the
All
45 general procedure reference may be had to either
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abrasives may be
.of the abovevpatents, ‘Other
alone.
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"where ‘~11. ‘is a ‘number between’ 1 and 2. -:In the
rcrmi-?a
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2
. Der-K1;
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used such as silicon carbide and other bonds
such as rubber or synthetic rubber and the ‘com
Jaination ?ller ‘of this invention may be :intro
'50 "duced'into the pores of ‘a vitri?ed ceramic rbo‘n-d
the constant K is used simply to make the ?gures
approximate some ‘?gures derived from earlier
formulae and so, for relative results it can be ig
nored. It follows that in a comparison of ?llers 55
in otherwise identical grinding wheels grinding
ed grinding wheel.
' Five wheels were made from No. 12 grit size
A1203 bonded with phenol formaldehyde, all
wheels being 16" in diameter by 2" thick with a
6" diameter central hole. In accordance with
2,408,319
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the usual practice the abrasive grains were ?rst
wet with furfural, then reactive A stage phenol
formaldehyde was added containing 4% by vol
her or by ratio of material removed to wheel
wear, Fesz for grinding stainless steel is no better
than cryolite. It also appears that for grinding
stainless steel potassium fluoborate is superior
to either cryolite or FeSz. On the other hand
the combination of cryolite and potassium ?uo
ume of the bond and ?ller of CaO as a dehydrat
ing agent. These wheels contained different ?ll
ers, which were mixed with the bond. The struc
ture of. these wheels ‘was identical, namely 58
volume per cent of abrasive and‘26-volume per
.borate is ,no better than cryolite for grinding
bullet steel. 'And the combination’ ‘of FeS2 and
potassium ?uoborate is de?nitely ‘superior to
cryolite for the grinding of bullet steel. Further
ditions with a swing frame grinder grinding ' more, as measured by the quality number
18-8 Allegheny steel with 140 pounds of total‘
M2
pressure between wheel and work at a speed of
W
9500 surface feet per minute.
Table 1 gives the wheel number, the ?ller and 15 the margin of superiority of Fesz plus KBF4 over
percentage thereof by volume of the total bond
the standard ?ller cryolite is greater than the
and ?ller, the wheel wear in cubic inches per
margin of superiority of KBF4 over cryolite.
hour W, the material removed in pounds per 1
For the manufacture of grinding wheels bond
hour M; the quality number as represented by the
ed with other bonds one may proceed as ex
‘expression
plained in my Patents No. 2,308,981 and 2,308,983
M2
which describes the manufacture of grinding
Kw I
wheels bonded with aniline formaldehyde, with
rubber, and the manufacture of vitri?ed grind.
the ratio of material removed .to wheel wear
cent of bond, leaving 16 volume per cent of pores‘.
The Wheels were then tested under identical con-yv
ing wheels.
A’
W
and a designation of the day on which the grind
ing was done.
Table 1
Wheel
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number
Filler
W
M
10.7
12. 8
‘9.3
10.0
‘V
- M2
M
KW W
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In the case of any organic bonded wheelthe
?ller of this invention, KBF4+iron sulphide, is
incorporated in the bond. In the case of a vitri
?ed grinding Wheel, the wheel is ?rst made in
the usual manner and then the pores thereof are
30 impregnated with the ?ller suspended in a sup
plemental bond, all as fully explained in each of
Patents No. 2,308,981 and 2,308,983.
Day
It will thus be seen that there has been pro
14 0.869
16 .828
No.1
No. 2
13. 5
10. 8
11.3
9. 1
17
14
. 837
.843
N0. 2
No. 1
13. 0
12.0
20
. 923
No. 2
vided by this invention grinding wheels and
35 other abrasive articles in which the various ob
jects hereinabove set forth together with many
thoroughly practical advantages are successfully
achieved. As many possible embodiments may
Seven wheels were made to a size 16" in di
ameter by 2.5" thick with a 6" diameter central 40 be made of the above invention, and as‘ many
changes might be made in the embodiment above
hole out of No. 12 grit size A1203 which was ?rst
set
forth, it is to be understood that all matter
wet with furfural after which reactive phenol
hereinbefore set'forth is to be‘ interpreted as
formaldehyde resin containing5% CaO by vol
illustrative and not in alimiting sense.
ume on the total bond and ‘?ller was added.
I claim:
These wheels were tested under identical condi
tions in a‘ swing frame grinder grinding bullet
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Table‘ 2
Wheel
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.number
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Filler
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W
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1
t
M2
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M
body, and the combination of iron sulphide and
potassium ?uoborate interspersed throughout the
bonded
XL276 ____ __
25% cryolite _____ __
XL278 ____ __
12.5%
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cryolite+
.4-
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‘.643
30.0
19.3
22
18.2
23
.095
No.4
29.2; 22.1
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30
.757
' No.8
~32
.878
‘No.4
-' No.8
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20.2
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4. An abrasive article comprising abrasive
grains and a phenol formaldehyde bond which
unites the grains asan integral body, Such bond
having. intimately associated therewith ?ller
comprising iron sulphide and potassium fluo
borate.
5. An abrasive article comprising abrasive
grains, an organic bond uniting the grains as an
integral body, and a ?ller comprising a :combi
Evaluating the ‘?gures in Table land Table;2 ~
-it‘ is seen that whether evaluated byi‘quality‘ num
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sulphide and potassium ?uoborate. ~
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XL11340____ 12.5% FeSz%l2.5% 23.0
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3. An abrasive article comprising abrasive
grains and a resinoid} bond which unites the
grains as an integral body, said bond having inti
mately associated therewith ?ller comprising iron
No.3
20.2
g
iron sulphide and potassium ?uoborate inter
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.725 _- No.4
.719. _ No.4
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spersed throughout the ‘bond.
VDvay
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grains, an organic-5 bond unitingthe grains as
an integral body, and ?ller of ?nely divided solid
.
20' 0010
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cryolite+
XL277 ____ .- 12§%€esi+12.5%
12.5% Keri.’
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18.3
17.9
17.4
12.5% KBF4.
XLll341____ 12.5%
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30.0
24.7
24.2
mass.
2. An abrasive article comprising abrasive
60.
XL1l39-l_______'_do _________ _.
XL1l39—2___ ____.do ___________ .-
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grains, a bond uniting the grains as an‘ integral
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M K‘T W
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1_. An abrasive article comprising abrasive
steel with a total pressure of 175 pounds between
the wheel and the work and at a speed of 9500
surface feet per minute. The :wheels had dif
ferent ?llers as indicated in Table 2, the head
ings whereof have the same meaning as in Table‘
--1. All these wheels had the same. structure
namely 54 volume per cent of abrasive, 34 vol
ume per cent vof bond including ?ller. andithe
lime, leaving 12% pores.’
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nation of Fesz and K_BF4.
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- SAMUEL S. KISTLER.
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