4.2.6 Critical Success Factors
In carding section, critical success factors play a very important role to enhance the quality of yarn such as
cleaning of material, %age of neps removal, grains (wt.) per yard and also CV of output material.
4.2.7 Defects in Carding and Causes
Causes of high sliver variation.
Nep formation
Holes or patches in card web
High sliver variation in due to difference in draft between card
Worn clothing and feed roller bearing also create variation in card sliver.
If auto leveler is not working properly than this will also create high sliver variation.
If auto leveler is off then check the wrapping of carding after every 30 minutes.
4.2.7.1 Causes for Neps Formation
Insufficient stripping
Dirty under casing ( grid bar)
Uneven flats setting
Under casing chocked with fly ( waste)
High roller speed
4.2.7.2 Causes for Holes or Patches in Card web
Poor flat stripping
Hooked or damaged wires on flats
Damaged cylinder
Cluster of cotton embedded on cylinder wires
4.2.8 Preventive Action
In order to avoid sliver variation draft calculation should be correct. Testing of sliver must be on time
at least 3 times during shift.
High sliver variation problem may also be due to maintenance problem. So concentrate on
maintenance. If our maintenance of machine will be there, then it will get more efficiency and better
quality will be achieved. If expiry time of some part of the machine is there, then on time it must be
replaced.
Now a days in advance technology the cards, auto leveler are electronic which adjust the sliver weight
automatically. For getting better result with automatic auto leveler, it is also necessary to check sliver
weight manually as well.[45]
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