Textile Fabric representation - Types and structure

Textile fabric representation

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1.3 Fabric Representation 
1.3.1 Methods of Weave Representation
1.3.2 Repeat of weave and shift
1.3.3 Drafts
1.3.4 Weaving plan
1.3.5 Lifting plan
1.3.6 Relations between Weave, Drafts, and Lifting.

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1.3.1 Methods of Weave
Representation
How can you describe the structure of a fabric?
We can use different ways: 
Plan diagram
Cross-section diagram 
longitudinal-section diagram 
Canvas method 

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Plan diagram
Cross-section diagram
longitudinal-section
diagram

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Main points about the canvas
method:
The canvas method is widely used in the world.

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1.3.2 Repeat of weave and
shift
Here is a plain weave. From the diagram, we can see, the
3rd warp thread has the same movement with the 1st, and
the 4th same with 2nd. Similarly, the 3rd weft thread is
same with the 1st weft thread; the 4th is same with the 2nd.
Thus, the weave repeats after 2 ends and 2 picks. So, we
define that: (shown in the next page)
Repeat:

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Thewarp repeat ----- the minimal number of warp
threads after which the movements of warp threads
repeat.
Theweft repeat ----may be defined analogically.
TheWeave repeat ---- a complete element of the
weave. 
Following are some examples:

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2) Shift (move)
Shift is the distance from a painted square on a thread
to its corresponding painted square on its adjacent
thread.
The shift can be counted in warp way, S
o
, and in weft
way, S
y
, (mostly in warp way)

The shift can be either positive or negative, depending
on the direction of counting. Counting from the left to
right or from low to high gives positive shift.

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Schematic diagram of shift

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1.3.3 Drafts 
1. The various Drafts
1) Some concepts

 ①Draft ---- The draft shows the number of shafts and the
manner in which the warp threads are drawn into the shafts.
 ②Why does it need to draft ?
The warp threads must be drawn into the healds, for separating the
warp threads to form shed.
 ③Position:
The draft is usually shown at the top of the weave diagram.

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The various drafts can be
classified as follows:
⑴. Straight ⑸. Divided
⑵. Skip and sateen⑹. Grouped
⑶. Pointed ⑺. Curved

⑷. Broken ⑻. Combined

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①
 
Straight draft 
 
Each successive thread is drawn in successive
shaft, i.e. the first thread in the first shaft, the
second thread in the second shaft, and so on
(see Fig. 1.9).
Fig.1.9

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② Skip draft  
This is used in weaving the fabrics with a high density of warp threads for 
reducing the friction between thread and thread as well as thread and healds
Three healds on each shaft
Two healds on each shaft

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2. Requirements to Drawing-in
1). The possibility of using a straight draft should be
studied first. Then the simplest type of draft, suitable for 
the given weave should be chosen.
2). The number of shafts should be as small as possible,
 but the density of healds is to be calculated and should
not exceed the standard value.
3). The distribution of threads on different shafts should
 be as uniform as possible. In some cases additional shafts
can be added to reduce the density of healds.

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4). It is advisable to use the front shafts with
minimum height of lifting for the threads with
 biggest number of intersections in the weave
repeat and for a weaker system of warp threads. 
5)Warps with different movement must not be
drawn into the same shaft and warps with same
movement can be drawn into different shafts
Requirements to Drawing-in

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1.3.4 Weaving plan
The weaving plan consists
of three elements placed in
a certain order: (1) weave,
(2) draft, or drawing-in, (3)
lifting plan.

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These three elements are closely
dependent on one another. If any
two elements of the weaving plan
are known, the third element can be
constructed. (see the figure on the
right)
Weaving plan gives the introduction
of weaving process.

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1.3.5 Lifting plan
In order to produce the required weave the designer 
has to provide a lifting plan for the purpose of 
controlling the lifting and lowering of the shafts. In
dobby shedding the plan is used either for pegging
a set of lags or cutting a paper card.

Lifting plans are indicated on the right of the
weave diagram.

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Example:
See the right figures, to
obtain the given weave there
are 4 vertical spaces in the
lifting-plan controlling the 4
corresponding shafts in the
draft

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1.3.6 Relations between
Weave, Draft, and Lifting.
Three elements of a weaving plan are dependent on
one another. Any element of the weaving plan can
 be constructed if two others are given.

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1. Construction of Lifting Plan
from the Given Weave and Draft.
● 
● 
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● 
● 
● 
● 

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2. Construction of Draft from a
Given Lifting Plan and Weave.
This diagram shown the lifting plan and the weave are given, and the
 problem is to construct the draft. 
To Construct the draft

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Principle and method
The number of vertical spaces
at C corresponds to the number 
of horizontal spaces at B. It
means that the first vertical
space at C controls the first
shaft, the second vertical space
controls the second shaft, and
so on. Then the draft is
constructed by comparing the
arrangement of the lifting plan
at C and weave at A. and so on.
● 
● 
● 
● 
● 
● 
● 
● 

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3. Construction of weave from
a Given Draft and lifting plan.

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Homework:
1. Explain the concepts: Repeat, warp repeat,
weft repeat, weave, shift.
2. Construct. Lifting plan from given weave
and draft. (See Fig.1)
3. Construct weave from given draft and
lifting plan. (See Fig.2)
Fig.1
Fig.2