Transcript Chapter Eight Pile Fabrics

Chapter Eight
Pile Fabrics

Introduction:
Pile fabrics are characterized by the brush-like
surface formed by tufts of warp or weft cut threads.
Cutting the threads can be done either on the loom
or on the machines of the fabric finishing
department.

Pile fabrics can be divided into the following two
groups:
1. Weft pile fabrics, which contains a weft cut pile produced
by cutting the weft threads at the fabric finishing process
by specially constructed knives.
2. Warp pile fabrics, having a pile produced on the loom
from the threads of an extra warp called a pile warp.
8.1 Weft Pile
Concept:
1) The piles are formed by weft
threads
2) There are two systems of weft
threads and one system of warp
threads
3) The main representative products
are corduroy and velveteen
Sample of corduroy fabric:
8.1.1 Corduroy

Introduction:
Corduroy is a fantastic fabric which possess soft
handle, clear stripes, lofty and full piles, good
strength, and aesthetic properties, so they are
widely used as apparel fabrics appealing to men
and women , young and old.
1. The principles of constructing
corduroy fabric.

The weave contains two pile
picks a, b and two ground picks
1, 2. The ground picks 1, 2
interlace with warp forming the
ground weave. Arrangement of
ground pick and pile pick is 1:2.
The pile pick floats over five
warp threads which are
convenient for cutting process.
Pile root

The pile picks interlace with the warp threads 5, 6 for
binding the piles where the intersections are called pile
roots.
After weaving, the pile weft was cut by specially
constructed knives between the warp threads 2 and 3
(where the arrow points in Fig. 8.1). Then, brushing it,
the piles will be upright, forming a full bulky band
corduroy.
The principles of the cutting are
described in the Fig. 8.2:
Show flash



The circular knife is placed on a mandril A indicated by the
arrow.
As the knives revolve, fabric advances towards in the
direction indicated by an arrow F.
A guide wire E is inserted in the fabric under the long weft
floats. The guide wires have these functions: ① guiding
the weft floats forming a loop-like: “race” to the knives,
and tautening them when they are cut, and ② keeping the
knives in the centre of each “race”. As the uncut fabric
approaches, the knives guide wires are conveyed along by
it, and consequently require to be pushed forward again
intermittently. This is accomplished by a series of spirally
arranged rotary cams.
2. The classification of
corduroys

According to the width of cord, the corduroys
are classified as following:
1)Fine (needle) corduroy, more than 11 cords/25mm.
2)Mid-wale corduroy, 9-11 cords/25mm.
3)Wide-wale corduroy, 6-8 cords /25mm.
4)Spacious-wale cording, less than 6 cords/25mm.

According to the ways of finishing process,
the corduroys are classified into :
1)Printed corduroy
2)Dyed corduroy

According to the materials used, the
corduroys are classified into :
1)Cotton corduroy
2)Blended corduroy
3. The weaves and setts

① Density :
Suitable warp cover factor is 50-60%; a suitable weft
cover factor is 140-180%; and the suitable ratio between
warp cover factor and weft cover factor is 1/3.
Notes: warp cover is defined as the fraction of the fabric covered by threads. It is
common to mention warp cover and weft cover separately
Say: e --- fabric cover; d --- diameter of thread; S --- space in warp/weft direction
So: eo = do/So
ey = dy/Sy
More details is coming up in chapter 11


② Ground weave
The ground weave’s function is to hold the piles,
the widely used weaves are as following: plain,
2/1 twill, 2/2 twill, 2/2 weft rib, 2/2 warp rib.
Different ground weaves used can achieve
different handle, fastness of the piles.
③ Selection of pile weaves
Three aspects should be considered for selecting
pile weave as the following a, b and c
a) The binding types
See Fig. 8.3 (A) and (B). There are two types of binding, Vtype and W-type. The advantage of V-type is easy to
tighten, and the short-coming is that the piles are easily
taken out. That of the W-type just reverse themselves.
b) The height of the piles
The height of the piles is decided by the length of the pile floats.
h (mm)=
C
50C
 10 
P
Po
2 o
10
Where: C —the number of the pile floats
Po —the warp density
c) Distribution of pile roots
The distributions of the pile roots decide the appearance of the fabric.
Some examples are shown on the next page. Some of the roots disperse,
and others are concentrated.
Various corduroy pile roots:
8.1.2 Velveteen

If the pile roots are
dispersed, the fabric
would be covered by
even piles. Those
fabrics are called
velveteen. Velveteen is
always raised during
finishing instead of
cutting.
Home works:
1. List the binding types of corduroy, and compare the
difference of each type.
2. Construct the following corduroy weaves
1) base weave 2/1↗, ground pick : Pile pick =1:2,
Ro=6, V-type binding.
2) Base weave 1/1 plain, ground pick : Pile pick =
1 : 2 ; Ro=8, W-type binding.