1.3 Fabric Representation

7/27/2019 1.3 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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The warp repeat----- the minimal number of warp

threads after which the movements of warp threads

repeat.

The weft repeat----may be defined analogically.

The Weave 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, So, and in weft

way, Sy, (mostly in warp way)

The shift can be either positive or negative, dependingon 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

Draft ---- The draft shows the number of shafts and themanner in which the warp threads are drawn into the shafts.

Why does it need to draft ?

The warp threads must be drawn into the healds, for separating thewarp threads to form shed.

Position:

The draft is usually shown at the top of the weave diagram.


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The various drafts can be

classified as follows:

. Straight . Divided . Skip and sateen . Grouped . Pointed . Curved . Broken . Combined


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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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Skip draftThis 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 ina 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 planare known, the third element can be

constructed. (see the figure on the

right)

Weaving plan gives the introductionof 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. Indobby 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 theweave 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 betweenWeave, 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 Planfrom the Given Weave and Draft.


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2. Construction of Draft from aGiven 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 spacesat C corresponds to the numberof horizontal spaces at B. Itmeans that the first verticalspace at C controls the firstshaft, the second vertical spacecontrols the second shaft, andso on. Then the draft isconstructed by comparing thearrangement of the lifting planat C and weave at A. and so on.


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3. Construction of weave froma 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

Date post:	14-Apr-2018
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1.3 Fabric Representation

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