COMBER

COMBER INFORMATION:-

FORMULA :-

COMBER NPM PRODUCTION FORMULA 8HRS:-

FORMULA = NPM*8*60*NO. OF HEADS*FEED PER NIP* GMS /PER METER*(100-NOIL)/1000*1000*100*EFF/100

EXAMPLE:-

Delivery speed in NPM = 475

FEED /PER NIP = 4.75

NOIL = 18%

Eff = 95%

    In the above formula 8 means 8Hrs(Per shift), 60 means 60 Minutes

=475×8Hrs×60Min×8 HEADS×4.75×70(100-18)÷1000÷1000÷100×95÷100 = 472 Kgs/Per shift.

COMBER FEED PER NIP FORMULA :-

FORMULA = 3.14×BOTTOM ROLLER DIA÷RATCHET WHEEL TEETH

EXAMPLE:-

Ratchet wheel teeth = 20

Bottom roller dia = 30

FEED /PER NIP = 4.71

=3.14×30÷20 = 4.71

TYPES OF FEED :-

1. Forward feed (concurrent feed):Feed of the sheet into the nippers occurs while the nippers move towards the detaching roller

2. Backward feed (counter-feed) : Feed of the sheet occurs during return of

the nippers

• Higher Noil % always improves the imperfections in the final yarn. But the

strength and other quality parameters improve up to certain noil %, further increase

in noil results in quality deterioration.

• In backward feed, the cylinder comb combs through the fibers more often than in

forward feed Therefore, the elimination of impurities and neps is always good.

However the difference is usually undetectable in modern high performance

combers of the latest generation.

• The FEED LENGTH has a direct influence on production rate, noil %, and the

quality of combing. High feed length increases the production rate but cause

deterioration in quality. Higher the quality requirement, feed length should be

lower. To some extent, the feed length may be decided by the length of the fiber

also.

Detaching length is the distance between the bite of the nippers and the nip of

the detaching rollers.This distance directly affects the noil %. More the

detaching distance, higher the elimination of noil.

• Needles of the top comb have a flattened cross section and are used with a point

density in the range of 22 to 32 needles per centimetre. More the needles, more

the noil%.

• The Depth of Penetration of top comb also affects the Noil %. If the comb depth

is increased by 0.5mm approximately 2% increase in noil will occur. When the

depth is increased, the main improvement in quality is seen in Neps. Over deep

penetration of top comb disturbs fibre movement during piecing which will

deteriorate the quality.

• Since the web from detaching roller is intermittent because of the intermittent

functions like feeding combing and detaching, to have a continuous web from the

comber, fiber fringes are laid on the top of each other in the same way as roofing

tiles. This process is called Piecing. This is a distinct source of fault in the

operation of Rectinlinear Combing. The sliver produced in this way exhibits a

periodic variation.

• As large a lap as possible with adapted lap weight which is as high and as

uniform as possible must be positioned in front of the comber. The better the

comber lap is prepared, the heavier the lap weight can be set on the comber and

the less the resultant noil waste with the same degree of cleanliness of the yarn.

• The higher degree of combing out is used in order to permit final spinning of

ultra-fine yarns or to increase the strength of a yarn. Reducing the lint content

improves the medium staple. However, not all cottons meet these requirements.

Low degree of combing out, on the other hand, frequently serve to improve purity.

When the card sliver is pulled through the needle bars, these separate off foreign

bodies, large neps and torn fibers. Light combing out has also been introduced to

a greater extent owing to the impairments in cotton purity influenced by

mechanical harvesting. Even when combing with minimum noil percentages,

there is a noticeable improvement in fibre parallelism in the sliver. Even the

smoothness and shine of the yarn are improved. It must thus be anticipated that

this method will become more and more popular in the future.