Advantages: Fast production speed, low processing costs, ability to lay short fibers, random arrangement of fibers leading to good isotropic effect in non-woven fabrics, and better uniformity compared to the dry method.
Disadvantages: Limited flexibility in product variations, high water consumption in the production process, and challenges in achieving large-scale continuous production.
The carding method is a crucial technique in non-woven fabric production. In the production of dry non-woven fabrics, carding plays a key role. It processes fiber raw materials, prepared through preliminary steps, into a thin web consisting of individual fibers. This web is then laid up, directly reinforced, or air-laid to create a three-dimensional random arrangement.
The air laying method utilizes aerodynamics to evenly deposit fibers into a continuously moving dust cage via airflow. To achieve a highly uniform web, the feed must be uniform, fibers properly distributed in the airflow, and the correct selection of airflow rate and fluid flow direction. The resulting fiber web exhibits a three-dimensional random distribution, with minimal differences in vertical and horizontal strength, and essentially displays isotropic characteristics.
Metal fiber mats formed using non-woven technology are in a bulky state, with fibers arranged in a disorderly and isotropic manner. To create an overall structure where each fiber overlaps and welds, maintaining a specific porosity and pore shape, high-temperature sintering is necessary.
Vacuum sintering furnaces are used for this process, employing techniques such as high vacuum with partial pressure and high-purity nitrogen quenching. Measures such as rapid temperature rise, high temperature, and short-time heating are implemented to precisely control furnace temperature, ensuring uniformity of the felt blank during sintering. This effectively prevents grain growth and secondary recrystallization, as well as the formation of brittle phases, ensuring sufficient ductility and corrosion resistance. Shrinkage of the felt is limited without the use of additives, thereby maintaining high porosity and keeping the pores open.
