Carding is a process in the manufacture of spun yarns whereby the staple is opened, cleaned,aligned, and formed into a continuous, untwisted strand called a sliver. A lot of defects occur during carding process. Defects or faults and their causes of carding are given below:
Defects in Carding:
- Sliver variation
- Cloudy web
- Hole in web
- High nep count
- Web slagging
- More cylinder loading
- Broken or malformed selvedge
- Excessive blowout
- Disappearing web
- Flat strip too heavy
- Taker-in snatch
- Loss in yarn strength
Important causes for defects in carding are mentioned below:
Causes for Neps Formation
- Insufficient stripping
- Dirty under casing ( grid bar)
- Uneven flats setting
- Under casing chocked with fly ( waste)
- High roller speed
- Poor flat stripping
- Hooked or damaged wires on flats
- Damaged cylinder
- Cluster of cotton embedded on cylinder wires
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 thesliver weight automatically. For getting better result with automatic auto leveler, it is also necessary to check sliver weight manually as well.
Preventive Action for Nep Formation
Over hauling of machine must be on time. During over hauling, setting of every part of the machine has to be checked. Flat setting play very important role for reducing nep formation. So flat setting must not be uneven.
Suction waste point should be properly working. This point must not be chocked. If there will be chock then neps formation will take place. Suction waste point also to be checked manually as well.
This problem is also related to maintenance. Over hauling of every machine must be on time. Wire of flats and cylinder have specific time limit of production. After that specific time limit it must be changed. As these play very important role by quality point of view.