Rieter

General

Index

As mentioned in chapter 2.2. there are only three man-made fibre types with a significant market share in the short fibre industry: the synthetic fibres polyester and polyacrylonitrile and the cellulosic fibres with viscose still representing the dominant fibre type in that category but also lyocell and modal fibres. The production methods of these fibre types will be explained shortly in the following chapters.

In general, a comparison of the production method of polyester (Fig. 11), polyacrylonitrile (Fig. 12) and viscose (Fig. 13) will reveal a basic difference between polyester on the one hand (two stage process) and acrylic / viscose fibres (single step process) on the other.

Each of these processing types has advantages and disadvantages inherent in its operating principle. The twostage operation in melt spinning gives the advantage of a lower number of spinning positions or nozzle jets. Furthermore, the separate downstream-process equipment can be stopped for maintenance or minor repairs without causing problems, because the step of coiling material in cans serves as a material buffer. The associated disadvantage is that of a greater requirement for floor space to support cans and enable can transport. The disadvantages and advantages of wet spinning can be derived from the same considerations. Both these considerations also apply for other fibres that require separate downstream treatment because they are made by melt or dry spinning processes (e.g. polyamide, polyolefin, and dry-spun polvacrvlonitrile fibres).