Yarn breaks
Determination
A yarn break during the spinning process occurs when the
actual spinning tension is higher than the actual yarn strength.
Forces in the yarn during the spinning process
The spinning tension is only 10 to 15%
of the yarn strength. On the other hand, the yarn strength during spinning is
also reduced (only about 85% of the twist reaches the spinning triangle). Disturbances like thin places, slubs (fibre fly),
foreign fibres, peaks in the spinning tension or most likely a combination of
two or more of the previous mentioned parameters lead to yarn breaks. Consider
also the twist multiplier (warp or knitting).
Causes for yarn breaks
In general, we distinguish between two kinds of yarn breaks:
·
Breakage during doffing
·
Breakage during the spinning process
Breakage during doffing
Cause of yarn breaks |
Remedy
(correction/solution)
|
· High curling tendency of the yarn |
·
Increase drafting system’s start-up
delay
|
|
·
Unthreading yarn
|
·
Change traveller type (e. g. form,
profile
·
Modify start-up program
|
|
·
Balloon stability too slowly built-up
|
·
Run-up faster or increase traveller
weight
|
|
·
Start-up characteristics
|
·
Optimise the starting program of the
ring spinning machine
|
|
·
Traveller jammed
|
·
Check condition of the ring, change
type of traveller
|
Breaks during spinning process
Cause of yarn break |
Remedy
(correction/solution)
|
|
·
Unsuitable traveller type
|
·
Try another traveller form, change
traveller profile, e. g. from f to dr profile
|
|
·
Uneven spinning tension, yarn tension
peaks
|
·
Poor centring of the rings, re
centre!
|
|
·
Spindle speed too high, yarn strength
insufficient
|
·
Yarn twist too low, increase the
twist or reduce the speed
|
|
·
Too long running time of the
travellers
|
·
Shorten the changing cycle
|
|
·
Poor condition of the rings
|
·
Replace rings
|
|
·
Climatic conditions not optimal
(fibre fly)
|
·
Optimise climate, adjust blower
nozzles
|
|
·
Yarn evenness (roving, impurities)
|
·
Optimise spinning preparation
|
|
·
Unfavorable raw material
|
·
Check raw material composition
|
|
·
Ring traveller severely worn
|
Reduce running time, test another traveller form
|
Yarn breaks are caused through many other factors like:
·
Preparation (Carding, Roving)
·
Conditions of the drafting unit (cots,
aprons, settings)
·
Centering of yarn guiding parts (snarl
wire, balloon control rings, spindles, rings)
Economic consequences of yarn breaks
Yarn breaks influence the efficiency of ring spinning
frames, the yarn quality and also followed processes. Therefore, low yarn break
rates are imperative for modern, successful spinning mills. With the choice of
the right ring and traveller for the processed fibres, there are reductions in
yarn break levels possible. When reducing the yarn breaks, costs for rings and
travellers become insignificant.
