The production of nonwovens takes place in three stages, although modern technology allows an overlapping of some stages, and in some cases all three stages can take place at the same time.
The three stages are:
Nonwovens manufacturing starts by the arrangement of fibres in a sheet or web. The fibres can be staple fibres or filaments extruded from molten polymer granules.
Illustrations of some of the methods used to form a web:
Webs have a limited initial strength right after the web formation (depending on various bonding mechanisms). The web needs therefore to be consolidated in one or the other way. The choice of the web consolidation method strongly depends on functional properties that are needed as well as on the type of fibres used..
There are three basic types of bonding:
The opportunity to combine different raw materials and different technologies accounts for the diversity of the industry and its products.
This diversity is further enhanced by a range of finishing treatments. By finishing the nonwoven can be tailored or functionalized to meet specific properties. Finishing treatments can be either mechanical (stretching, perforating, crimping etc) or chemical. With the latter one can modify the surface of the fibres and the nonwoven to change the haptics or the repellency of the nonwoven.
Nonwovens can be made conductive, flame retardant, water repellent, porous, antistatic, breathable, absorbent and much more. They can also be coated, printed, flocked, dyed or laminated to other materials.
Nonwoven manufacturing ends usually with large rolls of product. Converters convert -as the word says- this roll good into a consumer product.
Sometimes converting is done in 2 steps. Before manufacturing the finished product one might want to bring the rolled good one step closer to the final product by slitting, cutting, folding, sewing or heat sealing.