IS 13360-5-6: Plastics - Methods of Testing, Part 5: Mechanical Properties, Section 6: Determination of Impact Resistance by the Free-Falling Dart Method - Staircase Methods

12 Pages·1999·1.3 MB·English

by  Bureau of Indian Standards

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IS 13360-5-6 (1999): Plastics - Methods of Testing, Part 5:
Mechanical Properties, Section 6: Determination of Impact
Resistance by the Free-Falling Dart Method - Staircase
Methods [PCD 12: Plastics]
“!ान $ एक न’ भारत का +नम-ण”
Satyanarayan Gangaram Pitroda
““IInnvveenntt aa NNeeww IInnddiiaa UUssiinngg KKnnoowwlleeddggee””
“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता हहहहै””ै”
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“Knowledge is such a treasure which cannot be stolen”

IS 13360 (Part YSec 6) : 1999
IS0 7765-l : 1966

Indian Standard
SCITSALP - METHODS FO GNITSET
PART 5 MECHANICAL PROPERTIES
Section 8 Determination of Impact Resistance by the Free-Falling
Dart Method - Staircase Methods
ICS 83.080; 19.060

Q BIS 1999
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002
February 1999 Price Group 3
sdohteM of tseT for scitsalP lanoitceS ,eettimmoC PCD 32
LANOITAN FOREWORD
sihT naidnI dradnatS ( traP teS/5 6 ) hcihw si lacitnedi htiw 0SI l-5677 : 8891 scitsalP‘ -
noitanimreteD of tcapmi ecnatsiser yb eht gnillaf-eerf traD dohtem - traP 1 : esacriatS ’sdohtem
deussi yb eht lanoitanretnI noitazinagrO for noitazidradnatS ( 0SI ) saw detpoda yb eht uaeruB of
naidnI sdradnatS no eht nqitadnemmocer of sdohteM of tseT for scitsalP lanoitceS eettimmoC dna
lavorppa of eht ,muelorteP laoC dna detaleR stcudorP noisiviD .licnuoC
ehT txet of 0SI dradnats sah neeb devorppa sa elbatius for noitacilbup sa naidnI dradnatS tuohtiw
.snoitaived niatreC snoitnevnoc ,era ,revewoh ton lacitnedi ot esoht desu ni naidnI .sdradnatS
noitnettA si ylralucitrap nward ot eht :gniwollof
)a reverehW eht lanoitanretnl’sdrow raeppa’dradnatS gnirrefer ot siht ,dradnats yeht dluohs eb
daer sa naidnI‘ .’dradnatS
)b Comma ),( sah neeb desu sa a lamiced rekram elihw ni naidnI ,sdradnatS eht tnerruc ecitcarp
si ot esu a tniop ).( sa eht lamiced .rekram
nI siht detpoda dradnats ecnerefer sraeppa ot niatrec lanoitanretnI sdradnatS for hcihw naidnI -natS
sdrad osla .tsixe ehT gnidnopserroc naidnI sdradnatS hcihw era ot eb detutitsbus ni rieht ecalp era
detsil woleb gnola htiw rieht eerged of ecnelaviuqe for eht snoitide :detacidni
International Standard Corresponding Indian Degree of
Standard Equivalence
0SI 192 : 7991 scitsalP - dradnatS SI 691 : 6691 cirehpsomtA snoitidnoc for yllacinhceT
serehpsomta for gninoitidnoc dna gnitset ( revised) tnelaviuqe
gnitset htiw ronim
snoitaived
0SI 1954 : 2991 scitsalP - mliF dna liN -
gniteehs - noitanimreteD of egareva
ssenkciht of a elpmas dna egareva

ssenkciht dna dleiy of a ,llor yb

cirtemivarg seuqinhcet ( cirtemivarg
ssenkciht )
0SI 3954 : 3991 scitsalP - mliF dna liN -
gniteehs - noitanimreteD of -kciht
ssen yb lacinahcem gninnacs
nI eht esac of 0SI 1954 dna 0SI ,3954 eht lacinhceT eettimmoC elbisnopser for eht noitaraperp of
siht dradnats sah deweiver sti stnetnoc dna sah dediced taht yeht era elbatpecca for esu ni
noitcnujnoc htiw siht .dradnats
roF laciport seirtnuoc ekil ,aidnI eht dradnats erutarepmet dna eht evitaler ytidimuh llahs eb nekat sa
72 f CO2 dna 56 * 5 tnecrep .ylevitcepser
nI gnitroper eht stluser of a tset ro sisylana edam ni ecnadrocca htiw siht ,dradnats if eht lanif ,eulav
devresbo ro ,detaluclac si ot eb dednuor off, ti llahs eb enod ni ecnadrocca htiw SI 2 : 0691 seluR‘ for
gnidnuor off laciremun seulav ( revised )‘.
IS 06331 ( Part S/See 6 ) : 1999
IS0 7765-l : 1988
Indian Standard
SCITSALP - SDOHTEIIR FO GNITSET
PART 5 MECHANICAL PROPERTIES
Section 6 Determination of Impact Resistance by the Free-Falling
Dart Method - Staircase Methods
1 scope IS0 4681 : 1979, &s&s - Film 8nd sheeting - Determkwtion
Of 8Ver8g8 thickness Of 8 s8mpie 8nd 8V8r8ge thickness
8nd yield of 8 rol( by gfwimetfic techniques fgr8vknetriic
11.1 This part of IS0 7765 specifies methods for the deter-
thickn8ss).
mination of the energy that causes plastics film and sheet less
than 1 mm in thickness to fail under specified conditions of im- IS0 4583 : 1919, Pyestics - Film endsheeting - Determi~8tion
pact of a free-falling dart from a specified height that would
of thickness by mechanical awning.
result in failure of 50 % of the specimens tested.
3 Significance
1.2 Two methods of test are described.
3.1 Methods A and B are used to establish the mass of the
12.1 Method A employs a dart with a 38 mm f 1 mm dart causing 50 % of the specimens to fail under the conditions
diameter hemispherical head dropped from a height of specified. Data obtained by one method cannot be compared
099 m f 0,Ol m. This method may be used for materials directly with those from the other method, nor with those
whose impact resistance requires masses of about 0,05 kg to obtained from tests employing different conditions of missile
about 2 kg to fracture them. velocity, missile impinging surface diameter, effective speci-
men diameter, and specimen thickness. The results obtained
with particular values of these test variables are highly depen-
1.2.2 Method B employs a dart with a 50 mm f 1 mm
dent on the method of fabncation of the film or sheeting.
diameter hemispherical head dropped from a height of

1,50 m f 0,Ol m. Its range of applicability is from abou t 0,3 kg
3.2 The results obtained by methods A and B are greatly in-
to about 2 kg.
fluenced by the quality of the material under test. The con-
fidence limits of data obtained by this procedure can, therefore,
1.3 The measurement technique is the staircase method. A vary significantly, depending on the sample quality, uniformity
uniform missile mass increment is employed during testing and of gauge, die marks, contaminants, etc.
the missile weight is decreased or increased by the uniform in-
crement after test of each specimen, depending upon the result 3.3 Methods A and B have been found useful for specifi-
(failure or no failure) observed for the specimen. cation purposes. Correlation between test results and field per-
formance can usually ba established.
3.4 The impact resistance of film and sheeting, while partly
2 Normative references dependent on thickness, has no simple conelation with sample
thickness. Hence, impact values cannot be normalized over a
The following standards contain provisions which, through range of thicknesses without producing misleading data as to
reference in this text, constitute provisions of thii part of the actual impact resistance of the material. Data from these
IS0 7766. At the time of publication, the editions indicated methods are comparable only for sample sets that vary by no
were valid. All standards are subject to revision, and parties to more than f 10 % from the nominal or average thickness of
sgreements based on this part of IS0 7766 are encouraged to the specimens tested.
investigate the poesibility of applying the most recent editions
of the standards listed below. Members of IEC and IS0 main-
tain registers of currently valid International Standards. 4 Definitions
IS0 291 : 1977, Pyastics - Stendard atmospheres for con- For the purposes of this part of IS0 7765, the following defini-
ditioning 8nd testing. tions apply.

1
IS 13360 ( Part WSec 0 ) : 1999
IS0 7765-l : 1966
4.1 impact failure mass: The missile mass, estimated 6.5 Cushioning and shielding devices, to protect person-
statistically, at which 50 % of the specimens would fail in the nel and to avoid damaging the impinging surface of the dart.
specified test.
5.6 Collar, with inside diameter of approximately 7 mm and
4.2 missile mass: The total of the masses of the dart, the in- with set screw for securing collar to dart shaft.
cremental weights attached and the locking collar.
5.7 Darts, for methods A and 6, with hemispherical heads,
each fiied with a 6,5 mm f 0,l mm diameter shaft at least
5 Apparatus
115 mm long to accommodate removable incremental weights.
The mass of each dart shall be known to an accuracy of
The apparatus shall be constructed essentially as shown in
f 0,5 %. Dart heed surfaces shall be free of nicks, scratches,
figure 1, using the following components:
or other irregularities. The shaft shall be attached to the centre
of the flat surface of the head with its longitudinal axis perpen-
6.1 Specimen clamp, consisting of a two-piece annular dicular to the surface. The shaft shall be made of material that
clamp having an inside diameter of 125 mm f 2 mm. The is not magnetic end shall have a steel tip 12,5 mm rt 0,2 mm
lower or stationary half of the clamp shall be mounted rigidly so long at the end held by the electromagnet.
that the plane of the specimen is horizontal. The upper or
movable part of the clamp shall be designed to maintain
5.7.1 For method A, the dart head shall be 38 mm f 1 mm in
positive and plane contact with the lower part of the clamp
diameter. It may be constructed of smooth, polished
when in position. The clamps shall be provided with suitable
aluminium, phenolic plastic, or other low-density material of
means of maintaining sufficient contact to hold the test
similar hardness.
specimen firmly in place during the test.
NOTE - Pneumaticallyo perated clamps have been successfully 5.7.2 For method B, the dart head shall be 50 mm f 1 mm in
employed. diameter. It may be constructed of smooth, polished stainless
steel or other material of similar durability.
5.1.1 Rubber-like gaskets may be affixed to the specimen
contact surfaces of both clamps to provide a cushion to 5.6 incremental weights, made of stainless steel or brass
minimize thickness variation effects. Rubber gasketing and cylindrical in shape. Each shall have a centre hole that
3 mm f 1 mm thick, of 50 to 60 Shore A durometer hardness, allows free fit on to a shaft of 6,5 mm f 0.1 mm in diameter.
125 mm f 2 mm in inside diameter and 150 mm f 3 mm in
outside diameter has been found satisfactory for this purpose. The thickness of each shall be adjusted to obtain the
appropriate mass within f 0,5 %. Suggested sets of weights
5.1.2 Slippage of material greater than 0,lO mm in thickness are as follows.
may be minimized or eliminated by securing crocus cloth or
50 D garnet abrasive paper to the clamps, or to the rubber-like
5.8.1 For method A, 30 mm diameter weights.
gaskets if these are used, with double-faced adhesive tape so
that the abrasive surface is in direct c o ntact with the material to Number Mass, g
be tested. There shall be sufficient clamping force to eliminate

detectable slippage. Other means of red ucing slippage such as 2 or more 5
additional clamping devices or positive clamping surfaces may 8 15
be used provided that the test specimen is not weakened at the 8 30
inside wall of the specimen clamps and that the effective 8 60
diameter of 125 mm f 2 mm of the test specimen is not
changed. 5.8.2 For method B, 45 mm diameter weights.
5.2 Electromagnet, capable of supporting a 2 kg mass, for Number Mass, g
use in holding and releasing the dart assembly. It shall be equip-
2 or more 15
ped with a centring device to ensure reproducible drop and a
8 45
suitable source of electric power which may be interrupted to
8 80
energize and de-energize the electromagnet. Alternatively, the
use of air-operated or other mechanical release mechanisms is
permitted, provided uniform end reproducible release is 5.8.3 Optionally, additional weights, each 120 g f 0,5 % for
obtained. method A or 180 g f 0,5 % for method B , may eb constructed
for use if it is necessary to extend the missile mass beyond that
5.3 Positioning device, to hold the dart at a drop height attainable when using all weights in the standard set.
of 088 m f 0.01 m (method AI and 1.50 m f 0.01 m
(method B) from the impinging surface of the dart head to the
surface of the test specimen. The dart shall be positioned ver- 6 Test specimens
tically above the centre of the test specimen.
6.1 The test spectrnonss hall be large enough to extend out-
6.4 Micrometer, accurate to f 0,002 5 mm in the range side the specimen clamp gaskets at all points. The specimens

from 0,002 5 mm to 1 mm, for measuring specimen thickness. shall be taken from the material to be tested in a manner repre-
2
IS 13360 ( Part 5/Set 6 ) : 1999
IS0 7765-l : 1966
sentative of sound sampling practice, unless such sampling 8.2.4.1 Before dropping the missile on a clamped specimen,
constitutes a variable under study. The quantity of material draw a circle on the material using a marker pen in contact with
shall be sufficient to provide at least 30 test specimens. the inside wall of the upper clamp. Apply only the pressure of
the pen itself to the material.
6.2 The specimens shall be free of pinholes, wrinkles, folds,
or other obvious imperfections, unless such imperfections con- CAUTION - For safety reasons, remove the dart while
stitute variables under study. drawing the circle.
6.3 The specimen thickness shall be within f 10 % of the After the dart is dropped and prior to removing the specimen,
nominal value. draw another circle using a ball-point pen of another colour.
Distinct double lines at any point on the circumference show
that slippage has occurred.
7 Conditioning and testing atmospheres
7.1 Condition the test specimen at 23 OC f 2 ‘C and 8.2.4.2 If crocus cloth or sandpaper is affixed to the gaskets
50 % + 5 % relative humidity for not less than 40 h prior to to provide greater gripping, determine slippage simply by in-
testing for materials that require conditioning. In cases of dis- specting the clamped film area after impact for evidence of
pute, the tolerances shall be It 1 OC and f 2 % relative scratch marks produced as slippage occurred.
humidity.
8.3 Staircase testing (see 1.3)
7.2 The test shall be carried out in the same atmospheric con-
ditions as the conditioning. 8.3.1 Select method A or method B for use, as required by
the relevant material specification or as agreed between the in-
8 Procedure terested parties.
6.1 Determination of thickness 8.3.2 Measure and record the average thickness of the test
specimens in the area of impact to the nearest 0,002 5 mm
Determine the thickness of the material being tested by the (see 8.1).
method specified in IS0 4591 or IS0 4593.
8.3.3 Select a missile mass near the expected impact failure
NOTE - IS0 4593 is not suitablef or use with embossedf ilm and
mass. Add the necessary number of incremental weights onto
sheeting.
the dart shaft and put the locking collar into place so that the
weights are held securely in place.
6.2 Preparation of apparatus
8.2.1 Set up the apparatus for testing by method A or by 8.3.4 Select a missile mass increment Am appropriate to the
method B. impact strength of the sample. The value chosen for Am should
be such that three to six (but at least three) missile masses will

8.2.2 Energize the electromagnet and position the specified be employed in the determination. A Am value equal to some

dart (see 5.7) vertically with the steel shaft tip inse rted in the 5 % to 15 % of mf, the impact failure mass, is usually appro-
magnet adapter. Adjust the drop height (the vertical distance priate.
from the plane of a clamped specimen to the bottom surface of
the dart head) to 088 m f 0,Ol m for method A or to
8.3.5 Place the first test specimen over the bottom part of the
150 m It 0,Ol m for method B.
clamp, making sure that it is uniformly flat, free of folds, and
covers the gasket at all points. Clamp in place with the top part
CAUTION - For safety reasons, remove the dart while
of the annular clamp.
making position adjustments.
8.2.3 With a trial test specimen clamped between the 8.3.8 Energize the electromagnet and put the dart into pos-
specimen clamps and with no added weights on the dart, de- ition. De-energize the magnet to release the dart. If the dart
energize the electromagnet to release the dart and observe the bounces off the specimen surface, catch the dart after it
point at which the dart impacts the specimen, catching the dart bounces to prevent both multiple impact with the specimen
after it bounces off the surface of the specimen. If necessary, surface and damage to the hemispherical contact surface of the
adjust the electromagnet position so that, in repeated trials, the dart resulting from impact.
dart reproducibly impacts the centre of the clamped portion of
the spec,imen.
8.3.7 Examine the test specimen for any evidence of slippage.
If slippage occurs, reject the results for this specimen.
8.2.4 Check the apparatus periodically to make sure specimen
slippage is not occurring during testing. If slippage occurs,
reject the results. The likelihood of slippage increases with in- 8.3.8 Examine the specimen to determine whether it has or
creasing dart mass and with increasing drop height, and is has not failed. Failure is defined as any break through the
greater with some materials than with others. Slippage may be specimen that can be observed readily by feeling or by viewing

checked conveniently during routine testing of a sample at a the specimen under back-lighting conditions. Record the
missile mass wherein both failures and non-failures are being results on a form such as that shown in figure 2, using an o to
observed. Either of the following procedures is effective. denote non-failure and an x to denote failure.
3
IS 13360 ( Part S/Set 6 ) : 1999
IS0 7765-l : 1988
8.3.9 If the first specimen fails, decrease the missile mass by where
Am. If the first specimen does not fail, increase the missile
mass by Am. Continue testing successive specimens, decreas- ni is the number of test specimens for which failure
ing or increasing the missile mass by Am between drops occurred at a mass mi,
depending upon whether the preceding specimen did or did not
fail. Zi is the number of mass increments from mo t0 mi
(2 for m. is 0);
8.3.10 After 20 specimens have been tested, count the total
number of failures N. If N = 10 at this point, testing is com- ck
=N
plete. If not, complete testing as follows. ni (i.e. the sum of failed specimens).
i=l
8.3.10.1 If N < 10, continue testing additional specimens
until N = 10, then stop testing. An example of the calculation of impact failure mass is
presented in figure 2.
8.3.10.2 If N > 10, continue testing additional specimens
until the total number of non-failures (o - see 8.3.8) reaches
10, then stop testing.
10 Test report
9 Calculation
10.1 The test report shall include the following partiCUhrS:
Calculate the impact failure mass mf, in grams, as follows:
a) a reference to this part of IS0 7765;
mf = m. + Am b) a complete identification and description of the material
tested, including type, source, manufacturer’s code, prin-
cipal dimensions, and previous history;
where
m. is the lowest missile mass, in grams, at which failure cl the thickness of the material tested and the range of
thicknesses of the specimens tested;
was found for the k mass steps;
d) the test conditions and conditioning procedures, if
Am is the uniform mass increment, in grams, used;
applicable;
ck e) the method used (A or 8);
=A jn ;2
i=l f) the impact failure mass, to the nearest 1 g.

4
IS 13360 ( Part S/Set 6 ) : 1999
IS0 7765-l : 1988
Adjustable bracket r
\
,
Centring adapter
for dart, brass, $5 mm
centre hole
I
I
Support shaft
Compressed air line
0.66 m fO,Ol m - Method A
/-1,50 m fO,Ol m - Method B
Clamping cylinders
Movable clamp ring and gasket
Stationary clamp ring and gasket -
Specimen, between gaskets

Foam rubber dart SOP
D Removable weights
A Steel shaft tip 6.5 mm 00 by 13,5 mm long
E Collar and screw
B Dart shaft: 6.5 mm OD and at least 115 mm long,
12.5 mm long at bottom
C Hemispherical head: Method A - 36 mm f 1 mm in diameter;
Method B - 50 mm f 1 mm in diameter
Figure 1 - Apparatus for free-fal ling dart impact test
(Courtesy of ASTM)
.5