ISO 4593:1993 pdf download – Plastics – Film and sheeting – Determination of thickness by mechanical scanning
1 Scope
his International Standard specifies a method for the determination of the thickness of a sample of plastics film or sheeting by mechanical scanning. The method is not suitable for use with embossed film or sheeting.
NOTE 1 Where the above is not adequate and a higher accuracy is required, this method should not be applied but a more suitable measuring device or method selected. The determination of gravimetric thickness is described in IS0 4591:1992, Plastics – Film and sheeting – Determi- nation of average thickness of a sample, and average thick- ness and yield of a roll, by gravimetric techniques fgravimetric thickness) The measuring surfaces of the device shall comprise a plane lower face and either a plane or radiused up- per face. All surfaces shall be polished.
2.1.1 In the case of plane/plane measuring surfaces, the diameter of each face shall be between 2.5 mm and 10 mm and they shall be parallel to within 5 pm. The lower face shall be capable of being adjusted to conform to this requirement. The force applied to the measuring face shall be 0,5 N to 1,0 N.
2.1.2 In the case of planelradiused measuring sur- faces, the diameter of the plane lower surface shall not be less than 5 mm and the radius of curvature of the upper surface shall be 15 mm to 50 mm. The force applied to the radiused face shall be 0,l N to 0.5 N.
NOTE 2 Transmission of the measured values may be performed, for example, mechanically (by micrometer), op tically (by mirror instrument) or electronically (inductively).
3 Test specimens
Cut test specimens, about 100 mm wide, across the whole width of the sample. When required, take specimens at positions approximately 1 m apart in the longitudinal direction of the sample. The specimens shall contain no creases except those necessary for folding the film for presentation or packaging pur- poses. The specimens shall contain no other defects.
4 Procedure
4.1 Condition the specimens for at least 1 h at 23 “C + 2 “C. For moisture-sensitive films, the condi- tioning time and atmosphere shall be as stated in the specification for the material under test or as specified between buyer and seller.
4.2 Ensure that the specimens and the faces of the measuring device (2.1) are free from contamination, for example dust.
4.3 Check the zero point of the measuring device before starting the measurements and recheck after each series of measurements.
4.4 When determining the thickness, lower the foot gently to avoid deforming the material.
5 Precision
The precision of this test method is not known be- cause interlaboratory data are not available. When interlaboratory data are obtained, a precision state- ment will be added at the following revision.