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IS 3766 (1977): Method for calibration of pandulum impact
testing machines for testing metals [MTD 3: Mechanical
Testing of Metals]
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Indian Standard
METHOD FOR CALIBRATION
OF PENDULUM IMPACT TESTING MACHINES
FOR TESTING METALS
( First Revision)
Methods
of Physical
Tests
Sectional
Committee,
SMDC
Refkvscnting
Chairman
SNRI P. K. CRAKRAVAKTY
The Tata Iron & Steel Co Ltd, Jamshedpur
L mbars
National Test House, Calcutta
DR A. S. BHADURI
SHRI B. C. BISWAS ( Alternate 1
Hindustan Aeronautics Ltd, Bangalore
SHRI R. N. BOSE
DR M. K. MAUKEKAR ( Alternate )
SHRI R. N.
Ministry of Defence
L)XCTA
( DGOF )
SHRI D, Y. MOGHF ( AIkrnnte )
DEPUTY
DIRECTOR ( MET )-II,
Ministry of Railways
RDSO, I,UCKNOW
ASSISTANT DII~PCTOR ( MET ) ,
RDSO, LUCKNOW ( Alternate )
The Indian Tube Co Ltd, Jamshedpur
SARI D. DUTTA
Ministry of Defence ( DGI )
FHRI P. K. G~N~OP~DHYAY
SHRI D. K. MUKHERJEE ( Alternate)
Ministry of Defence ( R & D j
SHRI N. T. GEORGE
S111tr G. K. K. MOIZTY ( Alternate)
Direr;t;elhcneral
of
Supplies
& Disposals,
SHRI A. K. GUHA
e
SHRI P C. MUSTAF~ ( Alternate )
National Physical Laboratory ( CSIR ), New Delhi
SRRI M. h. DAS GUPT~
Blue Star Limited, Bombay
SH~I S. B. IDNANI
SHRI A. L. CHADRA
( Alternate )
Fuel Instruments & Engineers Pvt Ltd, Ichalkarnji
SHRI S. V. KULKAKNI
SHRI J. V. KULKARNI ( Alternate )
Usha Martin Rlack ( Wire Ropes ) Ltd, Calcutta
SBR~ V. M. KULKARNI
DR A. CAAKRABORTY ( Altrrnate )
The Tata Iron & Steel Co Ltd, Jamshedpur
SHRT M. C. KUMARASWAMY
DR T. MUKEERJEE ( Alternate )
The Indian Iron & Steel Co Ltd, Burnpur
DR D. M. LAKHIANI
SHRI R. DUTTA ( Alternate )
Avery India Ltd, Calcutta
SHRI K. S. LAKSHD~INAI~AYAN
SHRI R. D. SHARMA ( Alfernate )
( Continued on page 2 )
@
INDIAN
Copyright 1978
STANDARDS
INSTITUTION
This publication is protected under the Indian Copyright Act ( XIV of 1957 ) and
reproduction in whole or in part by any means except with written permission of the
publisher shall be deemed to be an infringement
of copyright
under the said Act.
IS 23766-1977
( Continued from page 1)
Members
Representing
Indian
Sugar
& General
Engineering
Corpn,
Yamunanagar
SHRI MADAN SHARX~ ( Alternate )
SHRI R. A. PADMANABHAN
Central Mechanical Engineering Research Institute
( CSIR ), Durgapur
M. N. Dastur & Co ( P ) Ltd, Calcutta
SHRI N. A. PRABHU
Hindustan Steel Ltd, Ranchi
SERI M. PRASAD
SRRI D. P. GAOSH ( Alternate )
National
Aeronautical
Laboratory
( CSIR ),
SHRI S. RADHAKRISHNAN
Bangalore
Mining & Allied Machinery Corpn Ltd, Durgapur
SHRI N. V. RACWAVAN
SHRI S. KUMAR ( Alternate )
Union Carbide India Ltd, Calcutta
REPRESENTATIVE
Directorate General of Civil Aviation, New Delhi
SERI F. C. SEARMA
Bharat Steel Tubes Ltd, Ganuar
SBRI K. C. SRIVASTAVA
Indian Register of Shipping, Bombay
SHRI
H. K. TANEJA
SHRIV. N. PANDEY (Alternate )
Directorate
General of Technical
Development,
SHRI
A. UMAMAHESWARAN
New Delhi
National
Metallurgical
Laboratory
DR VIED PRAKASH
( CSIR ),
Jamshcdpur
DR D. J. CHA~RAVARTI ( Alternate )
Associated Instrument Manufacturers ( India ) Pvt
SHRIH. C. VERXA
Ltd, New Delhi
SHRI 0. P. CRIJQR ( Alternate )
Director General, ISI ( Ex-o&-io Member )
SHRIC. R. RAMA RAO,
Director ( Strut & Met )
SHRIY. L. MIDHA
Secretary
Srrtu B. MUERERJI
Deputy Director ( Metals ), IS1
IS t 3766- 1977
Indian Standard
METHOD FOR CALIBRATION
OF PENDULUM IMPACT TESTING MACHINES
FOR TESTING METALS
(First Revision)
0.
FOREWORD
0.1 This
Indian
Standard
was adopted
by the Indian
Standards
Institution
on 12 December
1977, after the draft finalized by the Methods
of Physical
Tests
Sectional
Committee
had been
approved
by the
Structural
and Metals Division Council.
0.2 This standard
was first published
in 1966.
It was taken up for
review by the Committee
and is now being issued as a revised standard
with certain modifications
for requirements
relating to:
a) inspection of machine framework,
b) verification
of the pedulum, and
c) Test piece supports.
In the preparation
of this standard,
due account has been taken of
latest international
agreements
concerning
the use of SI units in relation
to impact testing.
0.3 This
standard
prescribes
the requirements
for the inspection,
calibration
and verification
of pendulum
impact
testing
machines
employed
for conducting
notched
bar impact
tests.
The method
of
calibration
specified in this standard is essentially static in nature and is
intended for the purpose of verifying machines by means of measuring
the potential energy after the test piece has been struck.
This standard
does not take
into account
the energy
absorbed,
other than when
fracturing
the test piece, corrected
to cover air resistance
and friction
losses.
0.4 This standard
also includes direct method of checking points on the
measuring scale of a bean-type machine by comparison
tests on unnotched
test pieces in the machine
under test and in a previously
calibrated
This method may also be used to check the performance
of
machine.
the machine
over a period of time, without
reference
to any other
machine.
This method, however, is not intended as an alternate method
to complete verification
and shall not be used without the consent of the
parties concerned.
3
IS:3766
-1977
0.5 This standard is based on ISO/R 442-1965 Verification of pendulum
impact testing machines for testing steels issued by the International
Organization
for Standardization,
which represents the consensus of
international opinion on the subject.
In the preparation of this standard
assistance has also been derived from BS 131 : Part 4 : 1972 Calibration
of pendulum impact testing machines for metals published by British
Standards Institution.
0.6 In reporting the result of a test made in accordance
with this
standard, if the final value, observed or calculated, is to be rounded off,
it shall be done in accordance with IS : 2-1960*.
1. SCOPE
1.1 This standard prescribes the method for calibration of pendulum
impact testing machines employed for carrying out notched bar impact
tests on metals.
2. TERMINOLOGY
2.1 For the purpose of this standard,
19697, shall apply.
the definitions
given in IS : 5069-
3. CALIBRATION
3.1 The calibration of the machine shall be carried out after installation
and shall cover the verification of the following elements which are
illustrated in Fig. 1, 2,, 3, and 4:
a) Machine framework ( the. structure
excluding the foundation );
supporting
the pendulum
b) Pendulum;
c) Test piece supports; and
d) Indicating equipment for the absorbed
scale and friction pointer ).
3.2 Machine
impact
energy ( namely,
Framework
9.2.1 Inspection
the following:
a) Horizontal
of the machine framework shall consist of determining
level of the test piece supports,
b) Free position of the pendulum,
*Rules for rounding off numerical values ( revised ).
tGlosrary of terms relating to methods of mechanical
testing ofmet&
IS : 3766 - 1977
c) Location of the pendulum
and
d) Side play of the pendulum
in relation
to the test piece supports,
bearings.
AXIS OF ROTATION
SCALE
BEARING
OF PENWLUM
FRICTION
POINTER
ROD OF PENDULUM
ANGLE OF TIP
DIUS OF CURVATURE
ENLARGED
L FOUNDATION
FIG. 1
CHARPY IMPACT TEST
OIR@ZTION OF IMPACT
/-TEST
PIECE
DISTANCE BETWEEN
SUPPORTS
FIG.
CHARPY
IMPACT
TEST PIECE
SECTION AT XX
SS:3766-1977
AXIS
OF ROTATION
RICTION
POINTER
L FOUNDATION
FIG. 3
TZOD IMPACT TEST
3.2.2 Tlie axis of rotation
of the pendulum
shall be horizontal
within
1/1000.
In the case of beam-type
machinism,
test piece supports should
be such that the axis of the test piece is parallel to the axis of rotation
of
the pendulum
within 1 /l 000. The plane of swing of the pendulum
shall
be perpendicular
to the transverse
axis of the Charpy specimen
anvils or
Izod vice within 3 : 1000.
3.2.3 A gauge in the form of a bar, approximately
55 mm in length
and of section 10 & 0.01 mm square, shall be located in the test piece
supports.
When the striking edge is brought into contact with the bar,
the coincidence
between the striking edge and the face of the bar shall
be within 0.03 mm over the full width.
3.2.4 The pendulum
for Charpy
and beam V-notch tests shall be so
located that the striking
edge of the pendulum
is within 0.5 mm of the
centre of the gap between the test piece supports.
6
IS:3766
RADIUS OF CURVATURE
OF STRIKING
EDGE
/-
ANGLE
OF
-1977
TIP
ANGLE BETWEEN
UNDERSlOE
OF
STRIKER
AND FACE
OF TEST PIECE
FIG.
Izon
IMPACT TEST PIECE
3.2.5 The pendulum for Izod tests shall be so located that the point of
contact between the striking
edge and the test piece is 22 f 0.5 mm
above the reference surface of the test piece supports. The angle between
the bottom
side of the striker and the face of the test piece shall be
100 Ii_ 1 ( see Fig. 4 ).
Any gauge used for checking
shall be within
0.2.
For all types of machine,
the side-play in the pendulum bearings
shall not exceed 0.25 mm, and the radial play shall not exceed 0.03 mm.
3.3
Pendulum
3.3.1 The verification
of the pendulum
consist of determining
the following:
( including
striker
shall
Initial potential energy;
Error in the indicated absorbed energy;
Impact velocity;
:] Energy absorbed by friction;
e) Positton of centre of percussion ( that is, distance
percussion to axis rotation );
of the striking edge;
f) Radius of curvature
g) Angle of tip of striker ( see Fig. 1 and 4 ); and
of striker.
h) Direction
b,
from centre
of
IS : 3766 - 1977
3.3.2 The initial potential energy A shall not differ from the nominal
The
initial
potential
energy is
value by more
than & 1 percent.
determined
by the following formula:
A=M(l-cosa)
where
M = moment
of the pendulum,
and
CC= angle of fall ( see Fig. 5 ).
The moment
of the pendulum
is determined
by supporting
the
pendulum
at a chosen distance 12 which should preferably
be greater
than l/2 from the axis of rotation
by means of a striking
edge on a
balance or dynamometer
in such a manner that the line through the axis
ofrotation
which joins the centre ofgravity of the pendulum is horizontal
The force F and the length
12 shall be determined
( see Fig. 6 ).
The moment M is the product F x 12.
to an accuracy of 0.2 percent.
The angle of fall (M) shall be measured to an accuracy
of 4 minutes of
arc.
NOTE- In certain carts, it may be necessary to remove the pendulum from the
machine to determine its moment by the method described above. Other methods
of determining Mare not precluded.
PENDULUM
FIG. 5
DIAGRAM ILLUSTRATING SWING OF PENDULUM
IS : 3766 - 1977
LENGTH OF PENDULUM I
-+
'1
OF TEST PIECE
FIG. 6
DIAGRAM ILLIJS~RATING SWING OF PENDULUM
3.3.3 The graduation marks of each scale corresponding to 0, 10, 20,
30, 50 and 70 percent of the full range of the scale shall be verified.
For
each of these graduation marks, the pendulum shall be so supported that
the graduation mark is indicated by the pointer, and the angle of rise
p then determined to within 4 minutes of arc. The indicated absorbed
energy A is given by the following formula:
A = M ( Cos p - Cos a )
1.I
The degree of inaccuracy of measurement 12, F and 6 when specified,
yields a mean total error of measurement of A, of approximately * O-3
percent of the full scale value.
The error in A, shall not exceed 3-O
percent of the indicated value or 1.0 percent of the full scale value,
whichever is greater.
( The potential energy after the test pieces has
been struck should never be less than one-tenth of the potential energy
before the test piece was struck. )
3.3.4 The impact
formula:
velocity u shall be determined
* = 2/ 2gl(
1 -
from the following
Cos a )
g = acceleration of free fall; its value may be taken as @81 m/s*, to
save measurement at the site of each testing machine; and
1 = distance from the axis of rotation of the pendulum to the centre
of the test piece for Charpy and beam V-notch tests, and to the
point of impact for the Izod test.
9
IS:3766-1977
The impact velocity shall
3 to 4 m/s for Izod machines.
be 5 to 5.5 m/s for Charpy
NOTE - For charpy machines manufactured before publication
an impact velocity of 45 to 7 m/r is permissible.
machines
and
of this standard,
3.3.5 The energy absorbed by friction includes air resistance,
bearing
friction and the friction of the indicating pointer.
The frictional losses
due to the indicating
pointer and to the remainder
of the machine may
be estimated as given in 3.3.5.1.
3.3.5.1 The machine is operated in the normal manner, but without
a test piece in position, and the angle of rise PI noted as indicated by the
pointer.
A second test shall then be carried out without resetting
the
indicating
pointer
and the new angle of rise pa noted.
For a simple swing of the pendulum from the angle of fall a, the
losses by friction (p) of the indicating
pointer during the rise is given by
the following formula:
P- M (
cosp1 - cospa)
The losses by bearing friction and air resistance
and the rise is given by the following formula:
P -
A4 ( Cos /3z -
(p),
during
the fall
Cos a )
The values of Pi and fig used for the calculation
the mean values of four determinations.
of p and p shall be
The total losses by friction and air resistance,
for one swing, shall
not exceed 0.5 percent of the initial potential energy of the pendulum.
3.3.6 The distance 11 from the centre of percussion
to the axis of
rotation is derived from the time ofswing of the pendulum, and it should
be within -& 1 percent of 1. The distance shall be determined
by swinging the pendulum through
an angle not exceeding
5 and by measuring
the time t of a complete oscillation
in seconds.
Ir is derived from the
following expression:
.!P
h=
where
23
the value of
7rs = 987,
and
g = 9.81 m/s*.
Therefore,
11 in metres
0.248
10
5 P.
IS:3766
-1977
3.3.7 The value of t shall be determined
within
0.1 percent.
For
instance
with a pendulum
having
a periodic
time of approximately
2 seconds this accuracy may be achieved by ascertaining
the mean value
oft derived from four determinations,
each of a total duration
T of 100
complete
oscillations,
provided
the quantity
( TM~S - TMin ), which
represents
the repeatability,
is not more than 0.2 second.
3.3.7.1 The radius of curvature
of the striking edge shall be checked
with a gauge.
Any gauge used for checking
shall be within f 0.1 mm
diameter.
For Charpy and beam V-notch tests, the radius of curvature
For Izod tests, the radius of curvature
shall be
shall be 2 to 25 mm.
0.5 to 10 mm.
3.3.7.2 The angle of the tip of the striker shall be checked with a
gauge. Any gauge used for checking shall be within 0.2. For the Charpy
and beam V-notch tests, the angle shall be 30 & 1. For Izod tests, the
angle shall be 75 & 1.
3.3.8 When the striking edge of the pendulum
makes contact with the
test piece, it shall be perpendicular
to the longer dimensions
of the test
piece within 2.
3.4 Test Piece Supports
3.4.1 Charpy and Beam V-notch Tests -
test piece supports
a) Distance
The following
dimensions
of the
shall be checked:
between
supports,
b) Taper of supports, and
c) Radius of curvature
of supports.
3.4.1.1 The distance
between
supports shall be 40?_:
gauge used for checking shall be withln * 01 mm.
mm.
Any
3.4.1.2 The taper of supports shall be 1 & 0.1 in 5, that is, a slope
of 0.18 to 0.22 ( approximately
11 & 1 ). Any gauge used for checking
shall be within 2.0. The radius of curvature
of supports shall be 1 to
1.5 mm.
Any gauge used for checking
shall be within + 0.1 mm on
the diameter.
3.4.2
Izod Tests -
The
following
dimensions
of the test piece supports
shall be checked:
a) Angle
and
b) Width
between
supporting
of locating
face of grips and
slot for test piece.
11
the horizontal
end,
IS : 3766 - 1977
3.4.2.1 A square or circular section shall be clamped in the grips.
If square, the bar shall be of the dimension
as given in 3.2.3; a bar of
circular
section shall be of diameter
Il.4 + 0.014 mm and of length
65 mm.
3.4.2.2 The angle between
of the grips shall be 90 f 0.5.
the face of the test piece and the surface
Any gauge used shall be within 0.1.
3.4.2.3 The width of the locating
groove shall be lO?g$rnrn
for
For circular test pieces, it shall be of semisquare section test pieces.
circular
cross section having a diameter
of 11.506 to 11.557 mm. Any
gauge used shall be within
f 0*025mm.
3.5
Indicating
3.5.1 The
following:
Equipment
verification
a) Examination
b) Examination
of the indicating
equipment
shall consist
of the
of the scale graduations,
and
of the indicating
pointer.
3.5.1.1 It is recommended
that for new machines the scale intervals
represents a maximum of 1 J for machines
having a capacity of 150 J or
less and 2 J for machines of greater than 150 J capacity for the Charpy
machines.
3.5.1.2
For Izod machines,
the scale intervals
for machines
of 80 J or less, and 2 J for machines
capacity.
shall not exceed 1 J
of greater than 80 J
3.5.1.3
It is recommended
that the length of the smallest division
shall be not less than 2 mm. The scale may also be graduated
in degrees
or fractions of a degree.
3.5.1.4 Tests shall be carried out to determine
whether the centre
The thickof circular scale is at the centre of the axis of the pendulum.
ness of the graduation
marks and the thickness of the indicating pointer
shall not exceed 0.2 of the minimum
scale spacing.
The indicating
pointer shall permit a reading free from parallax.
4. DIRECT
CHECK
4.1 This method
BY TESTS ON UNNOTCHED
involves
TEST PIECES
the following:
a) Selection
and preparation
of test pieces,
b) Tests in a previously cahbrated
machine,
c) Measurements
of dimensions
and tests
checked, and
d) Assessment of performance.
in the machine
NOTE - If the method is being employed to check the perfdrmance
~
over a period of time, tests under (b) shall not be required.
12
to be
of a machine
b.,
,_(
,,
IS:3766
I.
-1977
4.2 For each scale point to be checked, 5 Jv test pieces are required.
Jv
is preferably
6 and should not exceed
10. The test pieces may be cut in
consecutive
order from the selected
bar of metal
and numbered
in
sequence
so that two consecutive
numbers are given to continuous
test
pieces.
The
test pieces
should
be heat-treated
to possess uniform
properties such that they withstand bending without fracture or formation
of cracks,
and such that the edges of the grips do not make deep
indentations.
After treatment
the test pieces shall be machined together
to the dimensions
given below:
Value
Tolerance
Length
55 mm
+ 0.1 mm
Width
10 mm
Dimensions
Thickness
Variable
( see Note )
005 mm
& O-01 mm
NOTE - It has been found that thicknesses of 3 mm, 5 mm and 7 mm are suitable
for checking at absofbed energy levels of approximately 20 J, 70 J and 140 J respectively, using a mild steel in the normalized condition.
4.3 The test pieces numbered
1Jlr + 1, 2.X + 1,3.M + 1 and 4N + 1 are
bent in the reference machine.
Each test piece is mounted in the machine
so that the striker strikes a 10 mm wide face (see Fig. 7).
Let 7-1, Tz,
T8, Td and Tj be the quantities
of absorbed
energy,
arranged
in
If Ti - Tl is less than 5 percent of Tl, the uniformity
increasing order.
of metal is considered
satisfactory
and the remaining
~JV5 test pieces
may be used for checking.
It is assumed that bending each of these
5Jv-- 5 test pieces shall absorb a quantity of energy T3.
FRONT VIEW OF
IZOD TEST PIECE
TEST
dz3.5
FIG. 7
PIECE
OR 7mm
TEST PIECES
13
4.4 It shall be Bscertained that the niachine to be checked complies with
the requirements of 3.4. To verify the graduation mark corresponding to
the value Is, fitie of the 5.N - 5 test pieces are tested.
Let Tim, Tzm,
Tam, Tdrn and Tsm be the quantities of absorbed energy corresponding to
readings made on the scale of the machine being checked, arranged in
increasing order.
4.4.1 For these tests, each test piece shall be placed on the supports in
such a way that the striking.edge of the striker strikes it exactly in the
middle of its length.
4.4.2 Different graduation marks on the machine may be checked in
this manner by varying the thickness of the test piece, the value of T
being determined in each case by the method described in 4.3.
by the difference
4.5 Repeatability
is characterized
Accuracy is characterized by the following quantity:
T.m - T,
T3
Tsm -
Tim.
x 100
If T.5m - T,m does not exceed 10 percent of Tim, the repeatability
of the machine at the graduation mark corresponding to Ia is considered
satisfactory.
If the difference between Tam and Ta does not exceed 5 percent of
Ts, the accuracy of the machine at the graduation mark corresponding to
Ts is considered satisfactory.
If either of the above conditions is not satisfied, the machine shall be
verified and serviced as described in 3.
14
AmDMENT NO. 1
JUNE 1980
TO
IS:376601977 METHOD FOR CALIBRATIONOF PENDUi.Un
IMPACTTESTINGWUiIC(ES FOR TESTINGRETMS
Alterations
___'lr_L
Page 0, ckuu
9.81
m/s28
3.3.4, tirsrr
4) - substitute
for '0.81./s2~.
wuge 12, cktur S.4.2.2)
following
for the existin
- SPbrtitute
the
chme:
3.h .2.2 The aaglc betuecn face of the test piece
utd the surface of the @rips sl!mlZbe 90 21'.
Aay
grugr used shall be v5tb.b
0 .I.
*
&i
cl
AMENDMENT NO. 2
SEPTEMBER 1982
TO
IS:3766-1977 HETIIUD FOR CALIBRATION OF PEtIDULUtl
IllPACTTESTING WKHINES FOR TESTING METALS
(First
Corricgzndum
_---
Revision)
(Pmp
1'0.2O' jiw
11,
chme
3.4.1.2,
line
3) - Substitute
'2.00'.
f
,(sMM!
3)
____--____---
Repro~rny~lly hit,
ISI, New Jklhi,
I
I
_.
.-.
IndiK
