Technical point in blow room
1. Opening in blow
room means opening into small flocks. Technological operation of opening means
volume of the flock is increased while the number of fibres remains constant i.e.
the specific the material is reduced
2. The larger
the dirt particle, the better they can be removed Since almost every blow room
machine can shatter particles, as far as possible a lot of impurities should be
eliminated at the start of the process Opening should be followed immediately
by cleaning, if possible in the same machine
3. The higher the
degree of opening, the higher the degree of cleaning. A very high cleaning
effect is almost always purchased at the cost of a high fibre loss. Higher
roller speeds give a better cleaning effect but also more stress on the fibre
4. Cleaning is
made more difficult if the impurities of dirty cotton are distributed through a
larger quantity of material by mixing with clean cotton
5. The
cleaning efficiency is strongly dependent on the TRASH %. It is also affected
by the size of the particle and stickiness of cotton. Therefore cleaning
efficiency can be different for different cottons w the same trash %. There is
a new concoct called CLEANING RESISTANCE. Different cottons have different
cleaning resistance
6. If cotton
is opened well in the opening process, cleaning becomes caries because opened
cotton has been more therefore cleaning is more efficient
7. If
automatic bale opener is used. the tuft size should be as small as possible and
the machine stop should be reduced to the minimum Level possible
8. If Manual Bale openers are used, the tuft
size fed to the feed lattice should be as small as possible. Due to machine
harvesting; cotton contains more and more impurities, which furthermore are
shattered by hard ginning. Therefore cleaning is always an important basic
operation
9. In
cleaning, it is necessary to release the adhesion of the impurities to the
fibres and to give the part surface area an opportunity to separate from the
stock. The former is achieved mostly by picking of flocks. The later is
achieved by leading the flocks over a grid.
10. Using
inclined spiked lattice for opening cotton in the initial stages is always a
better way of opening the cotton with minimum damages. Of course the production
is less with such type of machines. But should bear in mind that if material is
recycled more in the lattice, neps may increase. Traditional methods use more
number of machines to open and clean natural fibres
11. Mechanical action on fibres causes some deterioration on yam quality, particularly in terms of neps
11. Mechanical action on fibres causes some deterioration on yam quality, particularly in terms of neps
12. Moreover it is true that the staple length of
cotton can be significantly shortened Intensive opening n the initial machines
like Bake breaker and blending machines means that shorter overall cleaning
lines are adequate
13. In a
beating operation the flocks are subjected to a sudden strong blow. The inertia
of the Impurities accelerated to a high speed is substantially greater than
that of the opened flocks due to the low air resistance of the impurities. The
later are hurled against the grid and because of their small size pass between
the grid bars into the waste box, while the flocks continue around the
periphery of the rotating beater by using a much shorter machine sequence.
fibres with better classic properties and improved spinnability can be produce
14. Air steams are often used in the latest
machine sequence, to separate fibres from trash particles by buoyancy deference
rather than beating the material against a series of grid bars
15. Cotton contain
very little dust before ginning Dust is therefore caused by working of the material
on machine. New dust is being created through shattering of impurities and
smashing and rubbing of fibre
16. However removal of dust is not sample Dust
particles are very light and therefore float with the cone n the transport
stream Furthermore the particles adhere quite strongly to the fibres It they
are to be eliminated
17. Removal of
finest particles of contaminants and fibre fragments can be accomplished by release
the dust into the air. like by turning the material over, and then removing the
dust-contaminated air
18. Releasing
the dust into the air occurs wherever the raw material is rolled, beaten or
thrown about Accordingly the air at such positions is sucked away perforated
drums, stationary perforated drums 2 stationary combs etc are some instruments
used to remove dust.