For the best veneering by hot melt resin, the MDF surfaces must be smooth. so, how we can decrease the surface roughness? how much roughness is acceptable for veneering by hot melt resin?
Thanks in advanced for attention
The typical roughness of the faces of MDF is surely acceptable for gluing of veneering (attention, I am talking about faces and not edges!). Problems could result from a particular thinny veneer. But if your wooden slice is more than 8/10 mm, you will obtain good results.
Pay attention to the bondability of MDF! Sometime panel made of wood fiber have been processed with too high temperature on the faces (in the hot press), so that there is a kind of "unfeeling" with glues in general.
Dear Marco Togni,
Thanks a lot for explanation. After sanding process, we can eliminate the weak layer of surface. So, How can too high temperature effect on adhesion quality of hot melt resin when we use high gloss veneer for surface? is there any chemical interaction between MDF surfaces and hot melt resin? or other factors can effect on adhesion properties?
Regards
Saman
Dear S. Ghahri
First, you need to specify the processes parameters affecting the MDF surfaces, design the experiments to investigate the effect of those parameters on the MDF surfaces and finally, find the optimal parameters that minimize the surface roughness. To help achieving your goals, you can use RSM working under Minitab software.
Good Luck
Omar
Salam
Dear Omar,
Thanks a lot for your comments. I have a limitation for designing a research plan. in industrial scale there are many factors which can effect on board properties like combination of different wood species, steaming, gluing, fiber and board density and etc.. because of that I am trying to find more important factors based on other researchers experiences.
Best Regards
Saman
As you said there are so many different variables playing role. But I think the surface roughness of the final board is highly dependent on the sanding process. In industry they normally use different sanding processes for different quality boards. I think you need to focus on sanding and try different things there. The other thing that might also play a role is the bulk density of the mat. More compact boards will be produced from higher bulk density mats and that can cause hot melt resin penetration issue. And finally you need to know whats going on chemistry/mechanically wise between hot melt resin and board surface.
Dear Mohammad,
Thanks for your comments. the problem is appearing big fiber on the surface (usually on the top side). The sanding process is going on perfectly and the smooth surface was achieved. After gluing the surface and veneering, the small defect like small bulb appear in the veneered surface.
Ciao
Saman
Dear Salam
To design an experiment, just determine the processes parameters and the range of each parameter, i.e the max. and min. values for each parameter, then within a minutes you can design your experiments using Design of Experiments approach. Perform your experiments scientifically and get your goals systematically. This is approach is reliable and can save time and effort.
Best wishes
How about fiber quality? do you have a lot of shives (fiber bundles)?There are so many factors controlling that but the main one is the refining energy.
We have a bit fiber bundles on the top of mat. Yes, i totally agree with you. But because of wood supply limitation, we use the mixed of different wood species. So, changing the steaming and refining can cuase to increase the smal fiber and dust. What do you think?
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