Estimate of Draft in Carded and Combed
yarn Manufacturing
by Dr. H.R. Sheikh, Professor Emeritus, Textile
Institute of Pakistan.Most of the
spinning mills in Pakistan process cotton to produce carded and
combed yarns involving the use of Ring Spinning Frames or
Compact Spinning System.
Open-End Rotor Spinning machines are also
used to produce coarse and medium category of carded yarn
counts. In general, the processes performed on cotton are
blowing, carding, doubling and drafting, roving formation,
spinning and winding of carded yarns.
For producing combed yarns, the material is
also passed through a combing set comprising of a pre-comber,
draw frame, lap former and generally four combers.
|
Spin Plan for
20 Ne Carded Yarn |
|
Serial No. |
Process stage |
Linear Density Grains / yard
(hank or count) |
Draft |
Remarks |
|
1 |
Blowroom Lap |
6125
(0.00136) |
2.5 |
Scutchers are not used
in modern blowrooms.
Material is fed to the
cards via chute feed system.
Waste extraction at
card has been assumed at 7.0% two passages of draw frames. |
|
2 |
Card Sliver |
70 (0.119) |
94.09 |
|
3 |
Finished Drawframe Sliver |
70 (0.119) |
64 |
|
4 |
Simplex Frame (Roving) |
0.75 |
6.30 |
|
5 |
Ring Spinning Frame (yarn) |
20 |
26.67 |
| |
Total Draft |
=
2,529,455.3 |
= 2.53
million |
In case of Open-End Rotor Spinning, Yarn is
spun from finished drawframe sliver and directly wound on cones
eliminating processes of roving and winding. Except in case of
the winding machine, the material is drafted at each process.
The draft at each processing stage is in accordance with the
Spin Plan and is estimated accordingly.
1. Carded yarns
Approximately 75% of Pakistani cottons are
in the medium long staple category. The 2.5% Staple Length
ranges from 26.20 to 27.80 mm or 11/3 to 13/32 inches. Carded
yarns up to 40 Ne can be spun form these cotton at commercially
competitive and industrially profitable output rate. Spin Plan
usually adopted for producing 20 Ne and the draft required at
each processing stage is tabulated below.
|
Spin Plan for
20 Ne Carded Yarn |
|
Serial No. |
Process stage |
Linear Density Grains / yard
(Hank or Count) |
Draft |
Remarks |
|
1 |
Card sliver |
65 (0.128) |
94.23 |
Chute feed system,
Carding Waste @ 7%.
48 slivers are fed to the Lap Former
Noils extracted @ 18%
Two passages of Drawframes.
Total draft in the case of combed
yarns is much higher than that for carded yarns. |
|
2 |
Pre-comber Draw Frame |
65 (0.128) |
8 |
|
3 |
Lap Former |
846.672 (0.00984) |
3.685 |
|
4 |
Combed Sliver |
50 (0.167) |
135.468 |
|
5 |
Finished Sliver |
50 (0.167) |
64 |
|
6 |
Simplex Frame Roving |
(2) |
11.98 |
|
7 |
Ring Spinning Frame (yarn) |
(60) |
30 |
| |
Total Draft |
8655.5 Million |
|
2. Combed yarns
A modern Combing set usually comprises of
one pre-comber draw frame, one lap former and four combers. The
combed sliver is also given two passages of draw frames similar
to procedure adopted for carded yarns before roving formation.
Spin Plan usually adopted for 60 Ne Combed yarn and draft
required at each processing stage is tabulated below:
Acknowledgement: Awwab Ahmed &
Hassan Mahmood.
(Final year students of TIP).
| 
