EUROSCANTRADING

Most often warp is caused by moisture differences in the corrugate board, for instances:

 

1. The liners may suffer from wet streaks, originating from uneven moisture across the paper machine or from water damages on the paper reels. More seldom moisture variations in the fluting medium cause warp problems, but when that happens it can cause the difficult "propeller warp".

 

2. The inner liner may differ in moisture content from the outer liner.

 

3. The edges of the belt over the heating section of the corrugator, may be worn and cause wet edges of the board.

 

4. The glue application has been uneven across the board.

 

5. The difference in quality between the inner and the outer liner is too big. It is especially difficult to make a flat board from one liner being a kraftliner and the other liner being a testliner.

 

6. Warp in the length direction of the web, is most often caused by too much or too little tension of the outside liner.