SIST EN ISO 294-4:1999

SLOVENSKI STANDARD
SIST EN ISO 294-4:1999
01-maj-1999
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Plastics - Injection moulding of test specimens of thermoplastic materials - Part 4:
Determination of moulding shrinkage (ISO 294-4:1997)
Kunststoffe - Spritzgießen von Probekörpern aus Thermoplasten - Teil 4: Bestimmung
der Verarbeitungsschwindung (ISO 294-4:1997)
Plastiques - Moulage par injection des éprouvettes de matériaux thermoplastiques -
Partie 4: Détermination du retrait au moulage (ISO 294-4:1997)
Ta slovenski standard je istoveten z: EN ISO 294-4:1998
ICS:
83.080.20 Plastomeri Thermoplastic materials
SIST EN ISO 294-4:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 294-4:1999

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SIST EN ISO 294-4:1999

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SIST EN ISO 294-4:1999

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SIST EN ISO 294-4:1999

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SIST EN ISO 294-4:1999

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SIST EN ISO 294-4:1999
Is0
INTERNATIONAL
STANDARD
First edition
1997-04-15
Plastics - Injection moulding of test
of thermoplastic materials -
specimens
Part 4:
I on of moulding shrinkage
Determinat
Moulage par injection des gprouvettes de matbriaux
P/as tiques -
thermoplas tiques -
Partie 4: D&termination du retrait au moulage
Reference number
IS0 294-4:1997(E)

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SIST EN ISO 294-4:1999
IS0 294=4:1997(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 294-4 was prepared by Technical Committee
lSO/TC 61, Plastics, Subcommittee SC 9, Thermoplastic materials.
Together with the other parts, this part of IS0 294 cancels and replaces
the second edition of IS0 294 (IS0 294:1995) which has been revised to
improve the definition of the injection-moulding parameters and has been
restructured to specify four types of IS0 mould for the production of the
basic specimen types required for the acquisition of comparable test data.
Care has been taken to ensure that the IS0 moulds described can all be
fitted in existing injection-moulding equipment and have interchangeable
cavity plates.
0 IS0 1997
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or by any means, electronic or mechanical, including
photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet central@iso.ch
x.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland

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SIST EN ISO 294-4:1999
IS0 294=4:1997(E)
@ IS0
IS0 294 consists of the following parts, under the general title Plastics -
Injection moulding of test specimens of thermoplastic materials :
- Part I: General principles, and moulding of multipurpose and bar test
specimens
- Part 2: Small tensile bars
- Part 3: Small plates
- Part 4: Determination of moulding shrinkage
Annex A of this part of IS0 294 is for information only.

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SIST EN ISO 294-4:1999
IS0 294=4:1997(E) @ IS0
Introduction
See IS0 294-l.
In the injection moulding of thermoplastics, the difference between the
dimensions of the mould cavity and those of the moulded articles
produced from it may vary with the design and operation of the mould.
Such differences may depend on the size of the injection-moulding
machine, the shape and dimensions of mouldings, the degree and
direction of flow or movement of the material in the mould, the sizes of
the nozzle, sprue, runner and gate, the cycle on which the machine is
operated, the temperature of the melt and the mould, and the magnitude
and duration of the hold pressure. Moulding and post-moulding shrinkage
are caused by crystallization, volume relaxation and orientation relaxation
of the material and by thermal contraction of both the thermoplastic
material and the mould. Post-moulding shrinkage may also be influenced
by humidity uptake.
IV

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SIST EN ISO 294-4:1999
IS0 294=4:1997(E)
INTERNATIONAL STANDARD @ IS0
Plastics - Injection moulding of test specimens of thermoplastic
materials -
Part 4:
Determination of moulding shrinkage
1 Scope
See IS0 294-1 :I 996, clause 1.
This part of IS0 294 specifies a method of determining the moulding shrinkage and post-moulding shrinkage of
injection-moulded test specimens of thermoplastic material in the directions parallel to and normal to the direction
of melt flow.
In contrast to IS0 2577, which describes the determination of shrinkage for thermosets, this part of IS0 294
excludes the effects of humidity uptake on moulding shrinkage. For cases when post-moulding shrinkage is caused
by the uptake of humidity only, see IS0 175.
The measurement of moulding and post-moulding shrinkage is useful in making comparisons between thermoplastics
and in checking uniformity of manufacture.
The method is not intended as a source of data for design calculations of components. Information on the typical
behaviour of a material can be obtained, however, by carrying out measurements at different melt and mould
temperatures, injection velocities and hold pressures, as well as at different values of other injection-moulding
parameters. The information thus obtained is important in establishing the suitability of the moulding material for
the production of moulded articles with accurate dimensions.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part
of IS0 294. At the time of publication, the editions indicated were valid. All standards are subject to revision, and
parties to agreements based on this part of IS0 294 are encouraged to investigate the possibility of applying the
most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently
valid International Standards.
IS0 175:1981, Plastics - Determination of the effects of liquid chemicals, including water.
IS0 294-l :I 996, Plastics - Injection moulding of test specimens of thermoplastic materials - Part 1: General
principles, and moulding of multipurpose and bar test specimens.
IS0 294-3: 1996, Plastics - Injection moulding of test specimens of thermoplastic materials - Part 3: Small plates.
IS0 2577:1984, Plastics - Thermosetting moulding materials - Determination of shrinkage.

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SIST EN ISO 294-4:1999
IS0 294=4:1997(E)
3 Definitions
For the purposes of this part of IS0 294, the definitions given in IS0 294-l apply, plus the following:
3.1 moulding shrinkage, SM:
The difference in dimensions between a dry test specimen and the mould cavity in
which it was moulded, both the mould and the test specimen being at room temperature when measured.
It is expressed as a percentage of the mould cavity dimension concerned.
The moulding shrinkage S Mp parallel to the melt flow direction is determined at the mid-point of the width of the
test specimen, and the moulding shrinkage SMn normal to the flow direction at the mid-point of the length.
NOTE - The value obtained for the moulding shrinkage is corrected to the room-temperature dimension of the mould. It is
reduced, therefore, by an amount corresponding to the thermal expansion of the mould.
This correction A&,, to the moulding shrinkage is given by
= -~XM(TM - 23)
ASM
where
aM is the linear coefficient of expansion of the mould, in degrees Celsius to the minus one (“C-l);
TM is the mould temperature, in degrees Celsius.
For example, for normal steel (aM = I,2 . 1 O-5 “C-l) and at a mould temperature 7’M of 100 OC, the correction ASM is -0,Ol 96.
rence in the dimen
3.2 post-moulding shrinkage, Sp: The diffe sions of a mou lded test specimen befo re and after
a post-moulding treatment, meas ured at room temperature.
It is expressed in percent, %.
The post-moulding shrinkage S,, parallel to the melt flow direction and the post-moulding shrinkage Spn normal to
the flow direction are defined in analogous fashion to SM, and SMn in 3.1.
3.3 total shrinkage, ST: The difference in dimensions between a test specim en after a post-mou lding trea tment
and the mould cavity in which it was moulded, measured at room te mperature.
It is expressed in percent, %.
The total shrinkage STp parallel to the melt flow direction and the total shrinkage STn normal to the flow direction
are defined in analogous fashion t0 sMp and SMr-, in 3.1.
3.4 cavity pressure, pc: The pressure of the thermoplastic material in the cavity at any time during the moulding
process, measured centrally near the gate.
It is expressed in megapascals, MPa.
3.5 cavity pressure at hold, pCH: The cavity pressure (3.4) 1 s after the end of the injection time tl (see figure I).
It is expressed in megapascals, MPa.
2

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SIST EN ISO 294-4:1999
IS0 294=4:1997(E)
@ IS0
4 Apparatus
4.1 Mould
Use a type D2 IS0 mould, giving 60 mm x 60 mm x 2 mm plate specimens, as specified in IS0 294-3:1996,
subclause 4.1 0
Reference marks may be engraved in the mould cavity to facilitate the measurement of the dimensions of
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