Problems, Causes and Remedies of Carding Process

Carding:
Carding is one of the most important operations in the spinning process as it directly determines the final features
of the yarn, above all as far as the content of neps and husks are concerned. It helps us both way to open the tuft into a single fiber and to remove the impurities and neps. So it is said that “The card is the heart of spinning mill”. Card feeding is done by two ways. One is manually and other is through chute feed system. In manual case the lap which is produced in blow room and it is feed to the card. In chute feed the material is feed through air flow system to card machine. It is important to say that lower the feed variation better is the carding quality. Lower the feed variation then draft variation will also be less. Approximately 90% cleaning efficiency is achieved with the help of carding machine. During carding process, different kinds of faults occur. Among them neps is remarkable fault.
Carding Process
Main Problems/Defects in Carding Process:
  1. Patchy web
  2. Singles
  3. Sagging web
  4. High card waste
  5. Low nep-removal efficiency
  6. Higher U% of sliver
  7. Bulky sliver
  8. Higher breaks
Causes and Way of Remedies in Carding:
Patchy web:
May be due to loading on the cylinder, damaged or pressed wire points, waste accumulation below cylinder under casing or defective under casing.

Singles:
May be due to lap licking, less feed in chutes, part of carded web getting sucked by the waste extractor, damaged doffer wire and direct air currents hitting the web.

Sagging web:
May be due to insufficient tension draft, very high humidity, worn out key in the calendar roller gears, heavy material fed to card and inadequate calendar roller pressure.

High card waste:
High card wastes are due to damaged under casings, higher flat speed, wider front plate setting, closer setting of flats, and higher pressure in suction unit and fibres getting ruptured.

Low nep-removal efficiency:
Blunt wire points, too wide setting between feed plate and licker-in, uneven settings, burrs in front plate/ back plate, and card wires of coarse type are the main reasons for low nep-removal efficiency.

Higher U% of sliver:
Worn out parts, eccentric movement in coiler calendar or table calendar rollers, uneven feed, waste accumulation in material patch, improper settings and loading of fibres on cylinder and flats are some of the reasons for higher U% of card sliver.

Bulky sliver:
Slivers become bulky by use of trumpet of a very large size and lower calendar pressure.

Higher breaks:
Very small trumpet, worn out trumpet, uneven sliver with bunches of fibres, worn out gears, damaged clothing, air currents disturbing the web, improper temperature and humidity and a very high tension-draft causes higher breakages of web and sliver.

References:
  1. Training and development of technical staff in textile industry by B. Purushothama
  2. http://www.scribd.com/doc/62931880/Spinning
  3. Reference book for spinning by Ezio Carissoni, Stefanno Dotti, Franco Fleiss, Luigi Petaccia, Lucia Pieri
  4. http://textilelearner.blogspot.com/2012/03/defects-in-carding-causes-for-defects.html
 

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