Rieter

Distribution of draft

Index

Three-line drafting arrangements, with two draft zones, are generally used in the short staple spinning mill In Asia still four- or five-line drafting arrangements are in use. The task of the draft in the first draft zone (break draft) is simply to prepare the main draft in the second zone. The fibers must be straightened and extended to such a degree that the main draft can immediately cause fiber movements, without still being strongly burdened with preparatory work. In this way, the main draft can be effected with less disturbance.

The extent of break draft normally lies below the critical draft region. In some cases, a higher break draft is needed, however, e.g. in drawframes and ring spinning machines (with drafts around and above 40). In this case, break drafts above the critical figure are selected.

The main draft must be adapted to the drafting conditions, mainly the fiber mass in the drafting zone and the arrangement of the fibers in the strand. The draft can be increased with increasing fineness of the intermediate product, and also with increasing parallelization of the fibers. Since the fibers in card sliver are relatively randomly oriented, the draft in the first drawframe passage should not be too high. Unless there are conflicting reasons, the draft can then be increased at the second passage and so on continually to the ring spinning machine.