Paper and paperboard silk direction and identification method

The direction of the paper web is also called the direction of the paper, the vertical and horizontal orientation of the paper, or the direction of the paper web. In the papermaking process, when the pulp flows from the headbox cloth to the screen, due to the kinetic energy of the pulp flow and the screen running at high speed, due to the combined effect of the kinetic energy of the pulp flow and the high-speed running screen, the fibers of the paper are roughly The direction of the web of paper is regularly arranged in the direction of the running of the paper machine.

The general rule: In the longitudinal direction of the paper and cardboard along the running direction of the paper machine, it is represented by "Machine Direction", and it is transverse to this direction, and it is expressed by "CD" (Cross Direction). The silk direction we usually say refers to the longitudinal direction of paper and cardboard.

There are many methods for recognizing the orientation of paper and cardboard, which can be roughly divided into two categories: calibration identification and detection identification.

First, the calibration method

1. Text description method:

Broadband paper and narrow-band paper, such as 787X1092mm paper, if it is broadband paper, then the wire is 787 direction, that is, short wire; if it is broadband paper, then the wire is 1092 direction, that is, filament.

2. Letter notation: There are two types. One uses the first letter of Short and Length to represent filament paper, ie, 787X1092mm (L) indicates filament paper, and 787X1092mm (S) indicates short yarn paper; the second uses machine running direction. Machine does not express, such as 787X1092mm said short wire, 787X1092mmM said filament paper.

3. Arrow notation: Mark the arrow on the outer package of the paper, and the direction indicated by the arrow is the direction of the paper.

4. Labeling method: Observe the position of the label on the outside of the paper package and the position of the certificate (usually, the label and the certificate are on the end face of the paper wire). When standing on the face of the label or certificate, the forward direction is the paper. The silk direction.

5. Customary writing: In the imagination, the paper stands in the direction of silk, and the bottom X is customary. Such as 787X1092mm paper, 1092 direction is the direction of the paper, that is, people often say that the filament paper or 43 (1092 mm two 43 inches) silk paper; if 1092X787mm paper, the 787 direction is the direction of the paper, also It is often referred to as short-filament paper or 31 (787 mm two 31-inch) silk paper.

Second, if the above mark is not used or the direction of the paper is not recognized by using the above mark, the following detection method is used to identify

1. Visual observation method: Place the paper sheet flat and observe light. The direction of the fine stripe on the paper surface is the direction of the paper.

2. Tearing method: tear the paper by hand, and it can be straightly torn, and the direction of the fiber where the edge of the gap is exposed is the longitudinal direction; the direction of the fiber with the larger edge plate and the edge fiber is the transverse direction.

3. Hanging paper method: cut each sample in a direction perpendicular to each other, overlap the paper strips, pinch one end, and the other end is free to bend. If the two strips are separated, the upper one is portrait and the lower one is horizontal. If the two strips are tight, the upper one is vertical and the lower one is horizontal.

4. Water immersion method: The sample was cut into 5050 mm, placed on the surface of the water, and the curling direction was observed. The direction parallel to the curl was the longitudinal direction of the paper.

(Author/Li Yutian)

Source: Soft Packaging Weekly