Rieter

Ambient conditions in the spinning mill

Index

The rotor spinning system imposes no special conditions and requirements on its environment; i.e. the customary ambient conditions in a spinning mill as regards temperature, humidity and air conditioning are always adequate for rotor spinning, and in many cases are even less critical than for ring spinning. Only relative humidity levels are slightly higher than for ring spinning.

Raw materials behave differently not only as regards their readiness to absorb moisture, their running properties are also affected by humidity levels in the spinning mill. Since the raw material spends several days in the spinning mill on its way through the spinning process, the moisture content of the fibers depends on the moisture content of the ambient air. Absolute moisture content in g/kg air therefore plays a crucial role in a favorable spinning climate. This moisture content is created by a combination of air temperature (°C or °F) and relative humidity (RH%). Table 17 shows the required absolute moisture content in g/kg air for a favorable spinning climate.

The more precisely the standard climate, i.e. relative humidity, is maintained within limits, the more trouble-free spinning operations are. While cotton and viscose react somewhat less problematically to changes in the ambient climate, changes soon become obviously apparent when man-made fibers are being processed.

If relative humidity is too low, this usually becomes apparent with man-made fibers in electrostatic charging and a consequent increase in ends down. When cotton is being processed, fiber damage, fiber fly and deposits in the spinning box and winding zones occur.

If relative humidity is too high, this results in lapping on cylinders and opening rollers with all fibers. The spin finish on man-made fibers tends to leave deposits on thread guide elements and in the fiber guide channel, thus obstructing fiber transport to the rotor. This then results in an increase in the number of neps and thick places.

Table 17 – Absolute moisture content in g/kg air for processing different raw materials