FELT ENGINEERING is an exclusive software that has been created, tested and now daily applied by BINET SUL LIRI for felt designing. A felt is a porous support, which guides the sheet through the press nip and transfers the pressure applied on the sheet causing it’s partial saturation and absorbing the relative water.
Binet Sul Liri uses an exclusive and highly evolved software to design its felts. It has been created, tested and now applied on a daily basis and is able to scientifically calculate the features of the felt before it is produced in order to evaluate whether the project choices will satisfy the expectations.
This software so-called FELT ENGINEERING is able to calculate besides the weight, thickness and permeability, also the dryness obtainable, the effective pressure of the fibers on the paper, the deformation and the compressibility of each component of the felt, the tortuosity of the capillaries, the vacuum that will be produced in the air conditioning, the optimal needling formula and finally the amount of needled fiber either within the thickness and on the opposite side by means of an automatic recalculation of the felts’ features in function of the needling itself.
The software allows to evaluate, during the designing phase, all the technical characteristics of the felt to be produced and of all the possible implications deriving from every adjustment made. In this way, often, a first felt supplied can perform better than standard ones. The opinion of an important scientist:
“When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind. It may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science.”
William Thomson (1824 - 1907)
also known as Lord Kelvin.
Felt Engineering is able to able to calculate all of the most important technical features of the felt using equations deriving from the physics of porous means, for example:
• distance between fibers in microns
• open surface in cm2/m2
• length, diameter and tortuosity of capillaries in mm and microns
• percentage of contact surface
• percentage of achievable dryness
• effective pressure of the fibers on paper in Kg/cml
• pressure drop at the suction box
• sum of loading loss in mH20 in every section of the felt
• felt thickness, new, compressed and critical thickness in mm
• total deformation and deformation for every felt section in mm
• total weight and weight in gr/m² for every felt section
• total air permeability and permeability of every felt section in cfm
• width of the nip in mm with and without the felt
• water eliminated in l/s
• drain speed in mm/s
• active volume in cm3/m2
• operating void volume in cm3/m2
Use of felts designed by similarity of position and production and eventually adjusted trough following supplies. Commercial standard felts can give an acceptable efficiency and life-time when well designed and produced: FELT ENGINEERING, guarantees optimization of machine clothing.
Like all other components of the paper machine, felts can be designed and produced using engineered methods instead of being produced empirically as done till today.
This is the only way to optimize the product’s performance and moreover the efficiency of the press. In fact a conventional felt can result to be a good felt when it is well designed, but it’s unlikely to be the best felt achievable, as like a Binet felt!