GB/T 21944.1-2022 Plastics film and sheeting - Determination of thickness by mechanical scanning
1 Scope
This standard specifies a method for the determination of the thickness of a sample of plastics film or sheeting by mechanical scanning.
This standard is not suitable for use with embossed film or sheeting.
2 Apparatus
2.1 Thickness-measuring device
Capable of measuring to the following accuracies:
——up to and including 100 μm to an accuracy of 1 μm (see note 1);
——above 100 μm and up to and including 250 μm to an accuracy of 2 μm;
——above 250 μm to an accuracy of 3 μm.
Note 1: Where the above is not adequate and a higher accuracy is required, this method shall not be applied but a more suitable measuring device or method selected. The determination of gravimetric thickness is described in ISO 4591:1992, Plastics - Film and sheeting - Determination of average thickness of a sample, and average thickness and yield of a roll, by gravimetric techniques (gravimetric thickness).
The measuring surfaces of the device shall comprise a plane lower face and either a plane or radiused upper 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 μm. 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 plane/radiused measuring surfaces, 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 0.1 N to 0.5 N.
Note 2: Transmission of the measured values may be performed, for example, mechanically (by micrometer), optically (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 purposes. 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 conditioning 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 During measurement, gently lower the measuring head to avoid specimen deformation and damage.
4.5 Determine the thickness of the specimens at points equally spaced along the length of the specimen, as follows:
a) for specimens less than 300 mm wide - 10 points;
b) between 300 mm wide and 1,500 mm wide - 20 points;
c) more than 1,500 mm wide - minimum 30 points,
Measurements shall not be taken within 50 mm of the edges of untrimmed rolls.
5 Precision
Foreword i
ISO Foreword ii
1 Scope
2 Apparatus
3 Test specimens
4 Procedure
5 Precision
6 Test report
Standard
GB/T 21944.1-2022 Special products of silicon carbide—Kiln furniture of reaction bonded silicon carbide—Part 1：Beams (English Version)
Standard No.
GB/T 21944.1-2022
Status
valid
Language
English
File Format
PDF
Word Count
6000 words
Price(USD)
180.0
Implemented on
2022-10-1
Delivery
via email in 1 business day
Detail of GB/T 21944.1-2022
Standard No.
GB/T 21944.1-2022
English Name
Special products of silicon carbide—Kiln furniture of reaction bonded silicon carbide—Part 1：Beams
GB/T 21944.1-2022 Plastics film and sheeting - Determination of thickness by mechanical scanning
1 Scope
This standard specifies a method for the determination of the thickness of a sample of plastics film or sheeting by mechanical scanning.
This standard is not suitable for use with embossed film or sheeting.
2 Apparatus
2.1 Thickness-measuring device
Capable of measuring to the following accuracies:
——up to and including 100 μm to an accuracy of 1 μm (see note 1);
——above 100 μm and up to and including 250 μm to an accuracy of 2 μm;
——above 250 μm to an accuracy of 3 μm.
Note 1: Where the above is not adequate and a higher accuracy is required, this method shall not be applied but a more suitable measuring device or method selected. The determination of gravimetric thickness is described in ISO 4591:1992, Plastics - Film and sheeting - Determination of average thickness of a sample, and average thickness and yield of a roll, by gravimetric techniques (gravimetric thickness).
The measuring surfaces of the device shall comprise a plane lower face and either a plane or radiused upper 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 μm. 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 plane/radiused measuring surfaces, 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 0.1 N to 0.5 N.
Note 2: Transmission of the measured values may be performed, for example, mechanically (by micrometer), optically (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 purposes. 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 conditioning 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 During measurement, gently lower the measuring head to avoid specimen deformation and damage.
4.5 Determine the thickness of the specimens at points equally spaced along the length of the specimen, as follows:
a) for specimens less than 300 mm wide - 10 points;
b) between 300 mm wide and 1,500 mm wide - 20 points;
c) more than 1,500 mm wide - minimum 30 points,
Measurements shall not be taken within 50 mm of the edges of untrimmed rolls.
5 Precision
Contents of GB/T 21944.1-2022
Foreword i
ISO Foreword ii
1 Scope
2 Apparatus
3 Test specimens
4 Procedure
5 Precision
6 Test report
