GB/T 6673-2001Determination of length and width of plastics film and sheeting (English PDF)

1.1 This standard covers test methods for measuring the "free" length of rolls of plastic

films and sheeting (see Chapter 2).

This method is applicable to film and sheet rolls with a length of less than 100 m and

serves as a reference method for verifying other measurement methods. Any other

length measurement method can be used as long as the measurement results are the

same as those of this method. If an automatic measuring device is used, the

measurements made for each plastic film and sheeting shall be verified according to the

steps specified in this method.

Since this method is relatively complicated, in the case of long rolls, when calibrating

the above-mentioned other measurement methods, it is allowed to use a plastic film or

sheeting about 100 m long measured by this method for calibration.

1.2 This standard also specifies the test method for measuring the average width of

plastic film and sheeting rolls, and the test method for measuring the width of plastic

film or sheeting specimens with a width of more than 5 mm (see Chapter 3). If the

specimen width is only slightly greater than 5 mm, the measurement accuracy of this

method is only 2%. This method specifies two procedures for measuring the width, and

which procedure shall be used depends on the width of the sample.

This method covers the test method for measuring the "free" width of rolls of plastic

films or sheeting.

This method is a reference method for verifying other measurement methods. Any other

width measurement method can be used as long as its measurement results are the same

as this method. If an automatic measuring device is used, the measurement of each

plastic film and sheeting shall be verified according to the steps specified in this method.

2.1 Apparatus

2.1.1 Sharp knife or razor.

2.1.2 Metal scale or profile. The length is greater than the width of the measured roll.

2.1.3 Flat surface. The length shall be at least 10 m, and the width shall be at least equal

to the width of the roll to be measured. There shall be a scale every 1 m along the two

longitudinal edges, and at least one edge shall be marked to 0.1 m.

2.2 Procedure

2.2.1 Unroll the film or sheeting into a stacked structure, with each layer not exceeding

2.2.2 Pick up the uppermost cut end of the material and spread it on a flat surface (2.1.3),

applying minimal tension to the material.

NOTE 1.One method of achieving the above requirement is to pass the film or sheeting over a freely

rotatable roller bearing assembly approximately 30 cm above the flat surface used to measure the material.

Align the cut end of the material with the zero mark on the flat surface. If necessary,

trim the end with a sharp knife or razor (2.1.1) and a metal scale or profile (2.1.2). Make

the metal scale or profile perpendicular to the longitudinal direction of the material.

This trimming of the end shall be limited to the minimum. At the other end of the flat

surface, align the material with the scale of the known length of the flat surface and

mark both sides of the material.

2.2.3 Move the material on the flat surface so that the marked point coincides with the

zero scale of the flat surface, and repeat the above steps to mark the other end of the

material.

2.2.4 Repeat the above steps until the entire roll of material passes through the flat

surface and is measured. If necessary, the final cut end can be trimmed in the same way

as the initial cut end.

2.2.5 The measured length shall be accurate to 0.1 m. The sum of all measured lengths

shall be reported as the roll length in meters, accurate to 0.1 m.

2.3 Precision

The precision of this test method is unknown because inter-laboratory data are not

available. A description of the precision will be included in a future revision when inter-

laboratory data become available.

2.4 Test report

The test report shall include.

a) Number of this standard;

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