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UDC 678.01 : 539.53 Ref. No.:
IS0
I N T ERN AT1 O NA L O RG A NI Z AT I O N FO R STA N D AR D I Z AT1 O N
IS0 RECOMMENDATION
,r
I
DU PONT CONSTANT LOAD METHOD
OF MEASURING ABRASION RESISTANCE
OF VULCANIZED NATURAL AND SYNTHETIC RUBBERS
ISf EDITION
L
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Copies to be obtained through the national standards organizations.
Also issued in French and Russian.
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BRIEF HISTORY
The IS0 Recommendation R33, Du Pont Constant Load Method of Mea-
suring A brasion Resistance of Vulcanized Natural and Synthetic Rubbers, was
drawn up by the Technical Committee ISO/TC 45, Rubber, the Secretariat
of which is held by the British Standards Institution (B.S.I.).
The draft proposal put forward by the Secretariat was considered and amend-
ed at the meetings held in London (1948), the Hague (1949), Akron (1950),
Oxford (1951) and Paris (1953).
On 28 August 1954, the Draft IS0 Recommendation proposed by the
Technical Committee ISO/TC 45 was submitted to all IS0 Member Bodies
and approved, subject to certain editorial amendments, by the following 20
(out of a total of 34) Member Bodies:
Austria Netherlands
*Canada *New Zealand
Pakistan
Denmark
Finland Portugal
India Spain
*Ireland Sweden
Union of South Africa
Israel
Italy United Kingdom
Japan *U.S.S.R.
*Mexico Yugoslavia
One Member Body opposed the Draft:
U.S.A.
The Draft IS0 Recommendation was then submitted by correspondence
to the IS0 Council which decided, in March 1957, to accept it as an IS0 RECOM-
MENDATION.
* These Member Bodies stated that they had no objection to the Draft being approved.
Date of the first edition: April 1957.
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lSO/R 33 - 1957 (E)
IS0 Recommendation R 33 March 1957 I
DU PONT CONSTANT LOAD METHOD
OF MEASURING ABRASION RESISTANCE
OF VULCANIZED NATURAL AND SYNTHETIC RUBBERS
FOREWORD
The world-wide use of the du Ponf constant load method of measuring abrasion
resistance and the absence of a recognized method whose results correlate with
wear in service justify the standardization of those features of the du Pont
method on which agreement has been reached in the last three years.
Some improved methods, now used experimentally, may be internationally
agreed upon in a few years’ time. Meanwhile, there is much to-be gained by
standardizing the du Pont method as far as possible. Close relation between
the test results and service performance is not, however, necessarily implied.
An alternative method of test, using very similar apparatus and procedure, but
imposing constant torque on the sample-holder instead of constant load, will
be considered for recommendation when further experimental evidence has
been received.
1. STANDARD COMPARISON RUBBERS
According to the type of rubber to be tested, one of the following two
standard rubber compounds is selected for comparison: either the high
quality tyre tread type or the footwear sole and heel type.
A high standard of mixing technique should be employed in the preparation
of these compounds, to ensure proper dispersion of the ingredients.
The compounds are:
“A” fyre tread fype standard compound
Natural rubber first-grade smoked sheet . 100
Zinc oxide . 5
Stearic acid. . 3
E.P.C. black . 50
Renzothiazyl disulphide . 1
Sulphur. . 3
Phenyl-beta-naphthylamine . 1
Vulcanization .- 40 minutes at 144 OC.
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lSO/R 33 - 1957 (E)
“E’ footwear sole and heel type standard comporrnd
Natural rubber first-grade smoked sheet . 100
Zinc oxide . 4
Stearic acid. . 3
Di-(2-ethyl hexy1)phthalate . 3
E.P.C. black . 60
Whiting . 60
Mercaptobenzothiazole . 1
Sulphur. . 3
Phenyl-beta-naphthylamine . 1
VuIcanization : 40 minutes at 153 OC.
2. TEST PIECE
Two test pieces are tested at the same time and compared with two test pieces
of the appropriate standard rubber. The pieces should be either 2 cm &
0.05 cm or 0.8 inch & 0.02 inch square and approximately either 1 cm or
0.4 inch thick, with suitable lugs for fixing in the sample-holder.
If desired, a small sample 2 cm x 2 cm x 0.5 cm or 0.8 inch x 0.8 inch x
0.02 inch may be prepared from a finished product or cut out with dies from
moulded sheet and attached by cold vulcanizing solution to the base portion
of a worn down used test piece, for test purposes.
3. APPARATUS
A disc which carries an abrasive surface is mounted on a shaft and rotated
at a uniform speed within the range from 34 r.p.m. to 40 r.p.m. The pro-
vision of a revolution counter is desirable.
The test pieces from the same compound are mounted, with their 2 cm or
0.8 inch square faces on the abrasive, on a bar, diametrically disposed across
the disc so that the centre of each sample is either 6.25 cm or 2.5 inches
from the centre of rotation.
The samples are held in contact with the abrasive by a force of either
3.62 kg or 8 lb weight by any suitable means free from friction and able
to follow axial movement of the sample-holder as wear takes place. (If the
abrasive disc is horizontal, dead weight can be used; if the abrasive disc
is vertical, a wire led through a central hole in the shaft with a weight of
either 3.62 kg or 81b attached at the rear can be used, as in the current
design of the du Pont machine.)
A lever arm attached to the sample-holder is provided with means (weights
and/or a spring balance) to restrain rotation and enable measurement of
frictional torque to be made, if desired.
The abrasive is in the form of an annular disc of either 16.5 cm or 6.5 inches
outside diameter with a central hole of either 7 cm or 2.75 inches in diameter
for fixing the disc to the rotating member.
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ISO/R 33 - 19W (E)
Silicon carbide abrasive grains mounted on stiff paper* have been found
to be suitable and the paper backing should have the following characteristics:
(a) the weight or paper substance should be at least 224gjm2 with a
tolerance of 5 per cent;
(b) the paper and the glue used to bond the abrasive grains should be
waterpro
...