3. PREPARATIONS FOR WEAVING START-UP
88
3.2
Weft-related Preparations (Mainly Spun Yarn)
3.2.1
Preparing Weft Yarn and Cheeses
Air jet weaving machines whose weft insertion speed exceeds 1500 m per minute (Reed space: 190
cm, machine speed: 790 rpm) require not only high-quality weft yarn but also high-quality weft cones
(cheeses). This is because the smooth release of weft from cheeses becomes more important as
the machine speed increases.
Generally, in those machines with a single drum, the weft insertion speed of 1100 m per minute
(Reed space: 190 cm, machine speed: 580 rpm) is the limit at which cheeses can follow the weft
releasing speed.
To weave at a speed of 1100 m per minute or more, it is recommended that double drums (2-color
drums) be employed for reducing the weft releasing speed on each drum to half.
Weft cone (cheese) specifications
––– Reference –––– Physical properties required for weft yarn (Minimum values)
Traverse width
6" or less (For fine count yarns, 3" recommended)
Winding angle
3° 30' for thick count yarns and 5° 57' for medium and fine count yarns
Winding hardness
50° to 70° (A cheese may collapse if the shore hardness or winding hard-
ness is low.)
Twill angle
The smaller the better (Be careful of yarns sticking among themselves.)
Knot
Knotless yarns are better (below 3 mm).
Ribbon winding
Apply the ribbon brake.
Bobbin diameter
For T/C45, 300 to 330 mm max. recommended
Steam set
Effective in some cases.
Number of winds
The more the better
Pure cotton yarn
Polyester yarn
blended with
35% cotton
Yarn spun by ring spinning
(Carded yarn)
Yarn spun by ring spinning
(Combed yarn)
Yarn spun
by open end
spinning
10
16
20
30
40
30
40
50
60
80
20
34
45
Yarn count fluctuation rate%
0 or less
2.0
2.0
2.0
2.5
1.8
1.8
1.9
1.9
1.9
1.6
1.9
1.9
Single ply yarn strength
g
840 or more 500
400
260
200
290
215
200
170
130
310
380
270
Strength fluctuation rate %
8.8 or less
10.2 10.3 10.7 11.0
8.4
9.5
9.3
10.2 10.9
9.9
10.2
11.9
Minimum single ply yarn strength g
705 or more 420
335
220
165
245
175
165
140
110
260
310
215
Elasticity
%
7.4 or more
6.7
6.5
6.0
5.7
6.0
5.6
5.6
5.5
5.5
7.3
10.5
9.5
U %
10.8
or
less 12.5 13.5 15.1 15.7 10.8 12.0 12.1 12.8 13.2
11.8
11.9
13.0
CV %
13.5
or
less 15.6 16.9 18.9 19.6 13.5 15.0 15.1 16.0 16.5
14.8
14.9
16.3
IPI value/1000 m
Thin
1 or less
4
30
60
80
6
15
20
30
60
4
6
20
Thick
20 or less
100
240
450
520
50
105
60
95
160
20
55
100
NeP
20 or less
100
200
420
600
50
90
85
115
140
310
80
110
Reference value
(in fiscal year 1987)
Japan Spinning Indus-
tries Association Data
IPI Value (Piece/1000 m)
Thin
1
4
35
71
100
8
24
32
37
95
4
9
33
Thick
11
62
152
326
403
31
74
46
74
124
10
37
74
Nep 14
68
153
322
482
37
60
64
81
108
218
58
85
Yarn type
Yarn count
(Ne)
Item
