During the production of MDF by ContiRoll press three main factors effect on MDF density as well as its quality. these factors are moisture content, heat and pressure. So, to modify the density profile these factors must change. Which factor has main role in density profile formation?
All of the 3 factors you mentioned! inside the hot press when change in moisture content (water evaporation) takes place and fiber gets dry the rate of change in mat properties like densifiction (gap change) and mat stiffness change a lot! this phenomenon is called mechanosorption. So mechanosrption is related to significant change in mechanical properties by changing moisture content. Mechanosorption is happening inside the press; densification starts when you are closing the press but the rate of densification starts to change significantly when the mat moisture content starts to change. We have studied this and developed a method to look at mechanosorption of fiber mat in lab scale (very small sample). I think that moisture content of the mat has a big role in mat densification and I am saying this based on mechanosorption effect but again definitely we need to have heat and pressure as you mentioned.
For most of MDF plants they are not aware of this effect (I mean scientifically) but based on their experience and looking at the vertical density profile graphs they can tell you that the problem is where. For example they can tellif you need to increase the pressing time or pressing temperature or the mat moisture content is not adjusted. There are some vertical density profile manuals which maybe you can find online (maybe not) which can help you fix the vertical density profile issue based on others people experience.
In MDF field there are very scientifically unknown subjects and I believe that a lot of research needs to be done in this area. And I think the reason that few studies have been done so far is due to MDF complexity. There are a lot of production factors having effect on board properties which all need to be carefully studied and this is very difficult to do.
Dear Mohammad,
Thanks for your attention and comment. As you explain many factors effect on the MDF quality. But the question is how heat and pressure transfer in different section of contiroll press effect on the board density profile.
Regard
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