Cotton is a hygroscopic material , hence it easily adopts to the atmospheric
airconditions. Air temperature inside the mxing and blowroom area should be
more than 25 degree centigrade and the relative humidity(RH%) should be
around 45 to 60 %, because high moisture in the fibre leads to poor cleaning
and dryness in the fibre leads to fibre damages which ultimately reduces the
spinnability of cotton.
Cotton is a natural fibre. The following properties vary very much between
bales (between fibres) fibre micronaire fibre length fibre strength fibre
color fibre maturity Out of these , fibre micronaire, color, maturity and
the origin of growth results in dye absorption variation.
There fore it is a good practice to check the maturity , color and
micronaire of all the bales and to
maintain the following to avoid dye pick up variation and barre in the
BALE MANAGEMENT :
In a particular lot
It the cotton received is from different ginners, it is better to maintain
the percentage of cotton from different ginners throught the lot, even
though the type of cotton is same.
- Micronaire range of the cotton bales used should be same for all the mixings
of a lot
- Micronaire average of the cotton bales used should be same for all the
mixings of a lot
- Range of color of cotton bales used should be same for all the mixings of a
- Average of color of cotton bales used should be same for all the mixings of
- Range of matutrity coefficient of cotton bales used should be same for all
mixings of a lot
- Average of maturity coefficient of cotton bales used should be same for all
mixings of a lot
Please note, In practice people do not consider maturity coefficient since
Micronaire variation and
maturity variation are related to each other for a particular cotton.
It is not advisable to mix the yarn made of out of two different shipments
of same cotton. For example , the first shipment of west african cotton is
in january and the second shipment is in march, it is not advisable to mix
the yarn made out of these two different shipments. If there is no
shadevariation after dyeing, then it can be mixed.
According to me, stack mixing is the best way of doing the mixing compared
automatic bale openers which picks up the material from 40 to 70 bales
depending on the length of
the machine and bale size, provided stack mixing is done perfectly. Improper
stack mixing will lead to BARRE or SHADE VARIATION problem. Stack mixing
with Bale opener takes care of short term blending and two mixers in series
takes care of long term blending.
- Tuft sizes can be as low as 10 grams and it is the best way of opening the
material(nep creation will be less, care has to be taken to reduce recyling
in the inclined lattice)
- contaminations can be removed before mixing is made
- The raw material gets acclamatised to the required temp and R.H.%, since it
is allowed to stay in the room for more than 24 hours and the fibre is
opened , the fibre gets conditioned well.
- more labour is required
- more space is required
- mixing may not be 100% homogeneous( can be overcome by installing double
If automatic bale opening machine is used the bales should be arranged as
let us assume that there are five different micronaires and five different
colors in the mixing,
50 bales are used in the mxing. 5 to 10 groups should be made by grouping
the bales in a mixing so that each group will have average micronaire and
average color as that of the overall mixing.
position of a bale for micronaire and color should be fixed for the group
and it should repeat in the
same order for all the groups
- It is always advisable to use a mixing with very low Micronaire
range.Preferably .6 to 1.0 . Because
- It is easy to optimise the process parameters in blow room and cards
- drafting faults will be less
- dyed cloth appearance will be better because of uniform dye pickup etc
It is advisable to use single cotton in a mixing , provided the length,
strength micronaire ,
maturity coefficient and trash content of the cotton will be suitable for
producing the required counts. Automatic bale opener is a must if more than
two cottons are used in the mixing, to avoid BARRE or SHADE VARIATION
It is better to avoid using the following cottons
- cottons with inseparable trash (very small size), even though the trash % is
- sticky cotton (with honey dew or sugar)
- cotton with low maturity co-efficient
Stickiness of cotton consists of two major causes. Honeydew from Whiteflies
and aphids and high level of natural plant sugars. The problems with the
randomly distributed honey dew contamination often results in costly
proudction interruptions and requires immediate action often as severe as
discontinuing the use of contaminated cottons.An effective way to control
cotton stickiness in processing is to blend sticky and non-sticky cotton.
Sticky cotton percentage should be less than 25%.