Under the same processing conditions, the causes of uneven thickness of non-woven fabrics are as follows:
(1) Low melting point fiber and conventional fiber are not uniform: different fibers have different cohesion. Generally speaking, low melting point fiber has greater cohesion than conventional fiber, and it is not easy to disperse. If the low melting point fiber is not evenly dispersed, the part with less low melting point fiber content can not form enough network structure, and the non-woven fabric is thinner than the low melting point fiber Thick phenomena are formed in places with large quantities.
（2） Incomplete melting of low melting point fiber: the main reason for incomplete melting of low melting point fiber is insufficient temperature. For non-woven fabric with low base weight, it is not easy to have insufficient temperature. However, for products with high base weight and high thickness, special attention should be paid to whether it is sufficient. The non-woven fabric at the edge is usually thicker because it has enough heat, and the non-woven fabric at the middle part is easy to form a thin non-woven fabric due to the lack of heat,
（3） High shrinkage of fiber: no matter it is conventional fiber or low melting point fiber, if the hot air shrinkage rate of fiber is high, it is easy to produce uneven thickness during the production of non-woven fabric due to shrinkage problem.
The main reasons for the uneven software and hardware may be as follows:
（1） The blending of low melting point fiber and conventional fiber is not uniform. The part with high content of low melting point is hard and the part with low content is soft.
（2） The non-woven fabric is soft due to incomplete melting of low melting point fiber
（3） The high shrinkage of fiber will also cause uneven hardness and softness of non-woven fabric.