Figure 1 shows a simplified schematic of a typical operation where man-made filaments are extruded through a plate with holes called a Spinnerette. The size of holes are typically 150 to 200 microns. The Spinnerette is included in what is called the 'spin pack'. Figure 2 shows a simplified diagram of a loose-fill spin pack assembly. Above the Spinnerette is the screen filter, which is primarily a point of use filter prior to the extrusion of the polymer melt.
Filters used are usually discs of stainless mesh or porous sintered powder.
The composition and size of the pack very much depends on the polymer, specification of the fibre and production rate. Finally the whole pack is secured with a gasket prior to installation in the stations. The number of stations depends on the scale of operation but can run into the hundreds. The primary function of the pack is a filter. The contamination removed by the spin pack comes from a variety of sources, including raw materials, pipe work and pumps.