GB/T 6672-2001Plastics film and sheeting - Determination of thickness by mechanical scanning (English PDF)

2.1 Thickness Measuring Instrument

It shall be capable of achieving the following precision.

--- 1 µm for dimensions up to and including 100 µm (see NOTE 1);

--- 2 µm for dimensions from 100 µm up to and including 250 µm;

--- 3 µm for dimensions exceeding 250 µm.

NOTE 1.When the aforementioned measuring instruments are inadequate for meeting higher

precision requirements, this method shall not be used; instead, a more suitable measuring

instrument or method shall be selected. 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) specifies the determination of

thickness by gravimetric techniques.

The measuring instrument shall have a lower measuring surface that is flat and an upper

measuring surface that is either flat or convex; all measuring surfaces shall be polished.

2.1.1 When both the upper and lower measuring surfaces are flat, the diameter of each

measuring surface shall be between 2.5 mm and 10 mm, and the non-parallelism between the

two surfaces shall be less than 5 µm. The lower measuring surface shall be adjustable to meet

the above requirements. The load applied to the specimen by the measuring surfaces shall be

between 0.5 N and 1.0 N.

2.1.2 When the upper measuring surface is convex and the lower measuring surface is flat, the

radius of curvature of the upper measuring surface shall be between 15 mm and 50 mm, the

diameter of the lower measuring surface shall not be less than 5 mm, and the load applied to

the specimen by the measuring surfaces shall be between 0.1 N and 0.5 N.

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