Bobbin dyeing technology: subjective reasons cause of non-recurrence of yarn through cone yarn dyeing are roughly as below:  winding quality, dye selection, dyeing process, operating factors, management problems, etc.

WINDING QUALITY INFLUENCES REPRODUCIBILITY

(1) Bobbin weight: When dyeing by immersion method, the depth of apparent color depends largely on the weight ratio of dye to yarn. In generally, only the number of bobbin is counted when the yarn is put on the cone yarn carrier, no longer weighed again. Therefore, the winding weight determines weight of loading yarn, be weighted after soft winding. Many factory production practices have proved that even without a fixed length meter, it is completely possible to weigh each bobbin and control the weight within the range of ± 1%. Some dyeing plants use "card" to measure the outside diameter, but because of the large error, it is not suitable. The different size of package yarn after dyeing also will get color difference betweent bobbin yarn.

(2) Bobbin winding density: The winding density of soft bobbin with direct relationship to resistance of circulation of dyeing liquor . High density, high resistance. Resistance magnitude affects shape of dyeing liquor circulation resistance curve, then affects main circulation pump, affects the circulation flow of the dye fluid, the circulation frequency of dye fluid and number of cycles within specified time are changed, so the amount of dye on yarn is changed, causing the color of yarn to be deep or shallow.

When some bobbin winding density is too small, sometimes the yarn will be out of the "groove", sometimes caused "collapse", the dye liquid will get "short circuit", not only the yarn is washed and dyed unevenly, but also rest bobbin dye liquid circulation will be reduced and cause light color.

(3)"Hole exposure" : Because the bobbin and the beam coil are full of holes for the dye to travel through, when the bobbin is not properly wound, or the reciprocating distance is not enough, "hole exposure" will occur. When dyeing, because the warp shaft is placed vertically in the main body of high pressure cone yarn dyeing machine, if winding is too loose, the yarn will fall due to gravity after wetting at sometimes, resulting in upper "hole exposure". The dye liquor will "short circuit" from the "exposed hole", not only wash the yarn on the end of the bobbin, but also affect the flow capacity of other bobbin.