PROCESS PARAMETERS IN CARDING - 3
- Higher cylinder speed helps fibre transfer. Higher the
production, higher should be the cylinder speed.
- Higher cylinder speed improves carding action, thereby
imperfections are reduced.
- Higher Licker-in speed for coarse fibres and diry cotton
helps to remove the trash and improves ,br> the yarn
quality.For fine and long cottons , higher speed results in
fibre ruputre, therefore, flat waste and comber noil will be
- Higher flat speed, improves yanr quality and at the same
time increases the flat waste
- With the same flat speed, higher the carding production
, lower the flat waste and vice-versa.
- Very high tension drafts will affect carding U%. It is
better to keep the draft between feed
roller to doffer around 75 to 95. The results are found better with these drafts.
- For a modern cylinder wire of 2mm height, grinding with
the normal grinding stone is not recommended. It is better
to use TSG grinder from GRAF. It is better to grind the wire
every 2nd or 3rd month, so that the sharpness of the wire is
- TSG grinde does not grind the wire, therefore if the
wire is worn out very badly the quality
improvement using this grinding machine will be nil. Frequent grindings are recommended. If TSG grinder is not availbale, it is better not to grind 2mm wires.
- The number of traverse should increase depending upon
the life of the wire. The number of traverse for successive
grindings should be like this 3,5,10,17 etc. Anyway the best
method is to confirm with the microscope. If the grinding is
not sufficient, the number of traverse should be increased.
- Doffer is still working with a concept of Land
formation. A normal grinding machine will be
good for doffer grinding. All the wire points should be touched by the grinding stone. A slow and
gradual grinding with the grind-out concept will give the best results. Harsh grindings will result
in burr formation on the land. This will increase the number of hooks in the fibre, thereby the effective length of the fibre from this card will be reduced.
- Flat tops grinding is very important. Everytime a flat
top is ground, yarn quality is improved.
It is better to use a grinding machine with the emery fillet. Frequent flat tops grinding will
result in less neps and the yarn quality will be consistent.
- Some mills increase the life of the flat tops compared
to cylinder wire. But it is better to
change flat tops and cylinder wire together for better and consistent yarn quality.
- It is a good practice to check the individual card
quality before changing the wire.
- Licker-in wire should be changed for every 150000 kgs.
Earlier changes will further improve the
- Stationary flats should be changed for every 150000 kgs.
But it is a good practice to change
the first 3 or 6 stationary flats at Licker-in side for every 100000 kgs. This helps to maximise the
carding effect between cylinder and doffer which is critical for better yarn quality.
- Lower the feed variation, better the carding quality.
Even if the card is with an autoleveller,
feed variations should be kept as low as possible (plus or minus 10%). With the latest chute feed systems, it is easy to control the feed variation with in 5%. Lower the feed variation, lower the draft deviation, therefore yarn quality will be consistent.
- If the card is with autoleveller, the nominal draft
should be selected properly. Improper selection
will affect sliver C.V% and yarn quality.
- Improper feed roller loading and the setting between
feed roller and feed plate will affect
the quality, especially C.V% and neps.
- Before mounting , the eccentricity of cylinder and
doffer should be checked. Eccentric cylinder and doffer will
affect the U% and will affect C.V.% also.
- Defective bearings , gears and timing belts will affect
- Uneven distribution of tension drafts will affect U%.
- Selvedge of feeding bat should be good. It should not be folded and double. This will increase the neps and sometimes it may result in cylinder loading. Lap fed to the carding machine should be narrower than the nominal width of the machine.
- For processing cotton, minimum 800 pascal suction
pressure should be maintained at trash master (at knife)for
effective removal of trash and dust particles.
- Worn or damaged scraper blades will lead to web sticking
to crush rollers. Insufficient pressure between scraper
blade and crush roller will also result in web sticking. If
the calender roller pressure is too high web sticking will
also be high.
- If Cylinder undercasing nose at doffer side is too long
for the type of fibre being carded
web disappearing problem will arise. If the nose is set too close to the cylinder, web disappearing problem will arise. Damaged and dull doffer wire also will result in web disappearing problem.
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