Surface variation (SFI/D)
Tests show that the surface index within a bobbin (base/tip) is spread up to ± 10%.
Reason
This can mainly be attributed to the tension differences during ring spinning. The yarn tensile strength fluctuates during bobbin winding and the ring rail stroke. The tensile strength peaks are very large in the area of the bobbin base. Increasing tension leads to deterioration in yarn irregularity and IPI values!
These relations must be taken into account when setting the limit values because such fluctuations do not normally have a negative influence on quality in the textile surface structure.
Variation
See the corresponding animation below
Test show that the surface index within a bobbin (base/tip) is spread up to ±10%.