BS EN ISO 20753:2014 pdf free
BS EN ISO 20753:2014 pdf free.Plastics -Test specimens.
Test specimens shall be prepared in accordance with the relevant material specification. When none exists,specimens shall be either directly compression or injection moulded from the material in accordance withISO 293,ISO 294-1,ISO 295 or lSO 10724-1, as appropriate, or machined in accordance with lSO 2818 fromsheets that have been compression or injection moulded from the compound, extruded from the compound orpolymerized and cast.
Strict control of all the specimen preparation conditions is essential to ensure that all test specimens in a setare in the same state.
All surfaces of the test specimens shall be free from visible flaws,scratches or other imperfections. Withmoulded specimens, any flash present shall be completely removed, taking care not to damage the mouldedsurface.
The broad sides of multipurpose test specimens shall be suitably marked (see Note), for injection-mouldedspecimens to distinguish between the sides formed by the cavity plate and the fixed plate of the mould (seeISO 294-1 or lSO 10724-1), for compression-moulded and machined specimens to identify any asymmetryresulting from the underlying moulding process.
For injection-moulded specimens, the sides can be identified by the impressions of the ejection pins and bythe draft angle.Compression-moulded and machined specimens shall be marked at their shoulders. IS0 barstaken from the central section of multipurpose test specimens shall be marked outside their central 64 mmsection, which is loaded during flexural testing.
NOTE Asymmetry with respect to thickness may influence the flexural properties，including the temperature ofdeflection under load (see Annex A).
4.2Injection moulding of test specimens
Test specimens shall be injection moulded as specified in lSO 294-1 or ISO 10724-1, as appropriate,andunder the conditions defined in the relevant International Standard for the material under examination or, if nosuch standard exists, as recommended by the manufacturer of the material or as agreed upon between theinterested parties.
4.3Compression moulding of test specimens
Test specimens shall be compression moulded as specified in lSO 293 or ISO 295, as appropriate, and underthe conditions defined in the relevant International Standard for the material under examination or, if no suchstandard exists, as recommended by the manufacturer of the material or as agreed upon between theinterested parties.
4.4Preparation of test specimens by machining
4.4.1 Preparation of test specimens by machining shall be performed either as specified in lS0 2818 or asagreed upon by the interested parties, using suitably processed injection- or compression-moulded sheets orshaped articles.
4.4.2 Bar test specimens having a width of 10 mm shall be cut symmetrically from the central parallel-sidedsection of a type A1 or type A2 test specimen.
The surface of the central parallel-sided section of the test specimens shall remain as moulded:
The width of the machined sections of the specimen shall be not less than that of the central parallel-sided section, but may exceed the width of the latter by not more than 0,2 mm.
During the machining operation, care shall be taken to avoid any damage to the moulded surfaces of thecentral parallel-sided section.
For the preparation, from type A1 or type A2 test specimens, of parallel-sided test specimens longer than80 mm in the case of type A1 test specimens or longer than 60 mm in the case of type A2 test specimens, thebroad ends of the specimen shall be machined to the width of the central parallel-sided section.
When machining test specimens from sheets or plates of which the history is not known， machine thespecimens from locations that appear appropriate or as agreed between the interested parties. Record thisinformation in the test specimen preparation report.BS EN ISO 20753 pdf free download.
