weaving litrature

Weaving Fundamentals and Design

© Copyright 2008-2011 North Carolina State University. All rights reserved.

Slide 1

Weaving Fundamentals

Weaving Fundamentals will cover these topics: You will learn how a woven fabric structure differs from a knit fabric structure. Warp and filling yarn paths will be discussed as they relate to woven fabric formation. The basic weaving motions needed to form a woven fabric will be explained with animations and videos to reinforce perception and understanding of the process of weaving. Woven fabric production will be covered using typical calculations to determine productivity along with a discussion of what factors influence the rate of productivity. Lastly, basic fabric designs will be highlighted with statements related to how design influences fabric properties.



Slide 2

Structure of Woven Fabric

Woven fabrics are formed by interlacing two sets of yarns. Yarns running along the length or machine direction of the fabric are called warp yarns, warp ends or simply ends. Yarns running perpendicular to the warp yarns and interlacing with them are called filling yarns, weft yarns or simply picks. Fabric count (sometimes called thread count or fabric construction) reveals how dense the fabric may be according to the yarns inserted per square inch of fabric. Fabric count is normally described using two numbers, the first representing warp yarns per inch in a given fabric and the second number representing the filling yarns or picks per inch. Another term used to refer to the ends per inch is sley. If the fabric count is 86x54, then one would know that the ends per inch or sley of the given fabric is 86 while the picks per inch is 54. The term thread count is normally used for squared constructions where the ends and picks per inch are the same number. For example, a 300 count sheeting fabric would have 150 warp yarns per inch and 150 filling yarns per inch. Some fabrics are described by using a series of numbers such as 86x54/16x12 where 16 would be the yarn count (English cotton count) for the warp yarn and 12 would be the yarn count for the filling yarn. Occasionally fabrics are over-constructed with too many yarns per square inch yielding a stiff fabric with poor drape or flexibility. The opposite would be a fabric too open with not enough yarns per inch yielding a structure that would be too loosely constructed and not very stable. Most woven fabrics will have fewer filling yarns per inch compared to the number of warp yarns per inch. Various fabric designs will create a different number of interlacing points or intersections of warp and filling yarns. These cross-over points present stress points in the fabric which affect the fabric stiffness and flexibility. The fabrics with fewer interlacing points will tend be more flexible and softer, with the opposite being true for fabrics with more interlacing points.



Slide 3

Woven Fabric Cross-Section

Looking at the simulated cross-sectional view of a woven fabric, as shown in this slide, reveals the warp and filling crimp produced by the interlacing yarns. This crimp gives the woven structure a 3-dimensional look showing that the fabric is not altogether flat. For this reason, more yards or meters of yarn are inserted into the fabric than yards or meters of fabric produced. Most fabrics, in their relaxed state, have more warp crimp than filling crimp.



Slide 4

Weaving Machine Parts

In weaving you begin with a collection of yarns on a loom beam and end up with a roll of fabric. In between these two points, there are various elements used to either help form the fabric or control the process in some manner. The warp yarns are unwound from the loom beam in sheet form and pass over a rather large diameter stainless steel roll called the whip roll which helps to guide the yarns forward. The whip roll can be adjusted up or down to control the warp yarn tension. The control of tension influences the fabric appearance and clarity of the design face. Each warp yarn is threaded through a thin metal drop wire which acts as a stop motion device. When a warp yarn breaks, the wire drops due to a lack of yarn tension to hold it up and the weaving machine will stop. This prevents the fabric from containing a missing end which would create a vertical line in the fabric, creating a second quality product. The harnesses are metal frames that contain thin metal wires called heddles. Each heddle has an eyelet or hole for threading each warp yarn. During the weaving process, the harnesses move up and down creating the desired design in the woven fabric. From the harnesses the warp yarns pass through a comb-like device called the reed. The reed spreads the warp yarn sheet out to a specified width called width-in-reed, or WIR, and beats each inserted filling yarn into the cloth fell. The cloth fell is the line across the fabric width where the yarns transition over to a woven fabric. On today’s shuttleless machines, large filling packages are placed at one side of the machine. The filling yarn runs off these packages and passes through a filling feeder which is a winding device for collecting filling yarn to be inserted as the next pick. The cloth take-up system pulls the fabric forward, allowing it to be formed into a cloth roll.



Slide 5

Weaving Machine Parts Warp Path

This animation illustrates how numerous warp yarns come off the warp beam, pass over the whip roll, go through the drop wires, pass through the heddles and reed and end up in a roll of fabric via the cloth take-up system. The time it takes a warp yarn to travel from the loom beam to the cloth roll is from 4 to 8 minutes. The actual time is influenced by the speed of the weaving machine and the filling yarns inserted per inch of fabric. During this time, the yarn is subjected to considerable abrasion. The size applied during the previous slashing operation helps to increase abrasion resistance.



Slide 6

Primary Motions Animation

There are five primary motions needed to weave a fabric. The first motion is shedding. Shedding means separation. In the case of weaving, it means the separation of the warp yarns with some forming the lower shed and others forming the upper shed. This separation is made possible by the up and down movement of the harness frames. The second motion needed is filling insertion. Through the open shed of warp yarns, the filling yarn is inserted so that it interlaces with the warp yarns to produce a particular weave design. Beat-up is the third motion that the weaving machine performs. It is done with the aid of a reed as it moves forward beating the filling yarn into the fabric. As these first three weaving motions are taking place in a timed sequence, the warp yarns are simultaneously let-off or unwound (the fourth motion) as the produced fabric passes to a take-up system (the fifth motion) to form a cloth roll. These motions are required on all weaving machines, whether they are hand looms or automatic looms.



Slide 7

Primary Motions Animation - Speed

This animation shows how the speed of unwinding the warp yarns must be higher than the speed of taking up the fabric. This difference in speed is due to the crimping of the warp yarns as they are interlaced with the filling yarns. Notice the harnesses separate the red and white warp yarns, allowing the white filling yarn to be inserted in front of the reed. After the filling insertion, the reed moves forward for the beat-up of the filling into the cloth fell. For simplicity, only two harnesses are being shown which means only a plain weave fabric design could be formed.



Slide 8

Weaving Motions Video

This video shows three of the primary weaving motions. Notice the harness movements or shedding which separate the warp yarns, the insertion of the filling yarns, and the subsequent beat-up of the filling yarn into the fabric. Notice in this particular video, the shed closes or crosses after each filling insertion. Notice, also, how close the heddles are situated in the harnesses. As a rule of thumb, only 24 to 28 heddles per inch can occupy a given harness. When the number of warp yarns becomes larger, the number of harnesses must be increased so that the heddles will not be too close together impeding the shedding process. Another point to mention is the sweep of the reed which can create significant yarn abrasion, thus necessitating the need for sizing the warp yarns.



Slide 9

Shedding



Slide 10

Cam Shedding

As previously mentioned, shedding is the separation of the warp yarns which provide an opening to insert the filling yarn. One of the simplest types of shedding is cam shedding. This type of shedding utilizes rotating cams to lift and lower the harnesses in a prescribed manner dictated by the woven fabric design. Cam shedding machines usually have from 6 to 8 harnesses, which allows one to weave only simple designs. However, some cam shedding machines today have as many as 14 harnesses. Cams are normally located at one end of the weaving machine in an oil bath near the floor.



Slide 11

Cam Shedding Photo

As shown in this photo, each cam has two parts – a low and high profile. As each cam rotates on the cam shaft, the high and low profiles come in contact with a cam follower which is connected to a lever or jack which in turn is linked to a given harness. Six jacks representing a six harness machine can be seen in this photograph. Spacers are used on the cam shaft where cams are not needed. This particular machine can accommodate up to ten cams, and thus control ten harnesses.



Slide 12

Cam Shedding Diagram

The linkage of each cam to an associated harness is illustrated in this diagram. To change design, one removes the current cams and replaces them with cams of a different shape or profile. For example, a plain weave will use an entirely different set of cams than a 3/1 twill weave. An inventory of cam shafts for different designs can be kept, so as to reduce the time taken to make style changes.



Slide 13

Cam Shedding Animation

This animation shows how the individual cams control the movement of a specific harness. The movement determines the woven design in a fabric.



Slide 14

Cam Shedding Video

This video insert focuses on the cam movements showing the lifting and lowering of the harnesses. Many times two harnesses contain warp yarns for forming the fabric edges or selvages. The remaining harnesses weave the body of the fabric. This particular machine has a tucking device which tucks the end of each cut filling yarn into the fabric edge. Thus it is called a tucked-in selvage. In this case, all six of the harnesses would be weaving the body of the fabric.



Slide 15

Dobby Shedding

A second type of shedding is called dobby shedding. Chains of wooden bars with pegs inserted, plastic or mylar sheets with punched holes or computer controls are used to dictate the weave design. The number of harnesses used can range from 8 to as many as 28 or even higher. Thus more complex designs with larger repeats can be woven, including geometric figures and spot weaves along with complex pattern stripes. Many machines today have electronic shed control which makes changing designs much simpler and quicker than with earlier technology.



Slide 16

Dobby Shedding Photo

An electronic dobby is shown in this photograph. The movements of the harnesses and associated jacks are created electronically with the aid of electromagnetism. This technology allows the use of CAD systems to develop a given design, modify it to be exactly what is wanted and then download it to the weaving machine. This eliminates the necessity of producing many samples and taking machines out of production for sample work. This particular machine has an 18 harness capability.



Slide 17

Dobby Shedding Video

This video insert focuses on the electronic dobby control system raising and lowering the harnesses. The harnesses can be seen moving up and down on the weaving machine. Notice the warp yarns being controlled by the harnesses. Dobby machines can produce any design done on a cam machine plus more elaborate designs.



Slide 18

Jacquard Shedding

A third method of shedding, called jacquard is used to produce larger design patterns. Tapestries and damask fabrics fall under this method of shedding. Originally jacquard looms used punched cardboard cards to control individual warp yarns. Later, mylar sheets with punched holes were used and still later, computer controlled jacquard heads. The earlier types of jacquard shedding tended to be slow while machines with electronic jacquards can operate at a much higher rate of speed. Design capability on these machines is virtually unlimited, typically producing more expensive fabrics.



Slide 19

Jacquard Shedding Photo

In jacquard shedding individual heddles are connected to the jacquard head located above the weaving machine. Draw cords, as shown in the photograph, are the connecting devices used and easily identify a jacquard machine. On these machines, the drawing-in of the warp yarns must take place at the machine and not in a separate area. Thus machine downtime is higher, leading to a lower efficiency process. Notice the large design repeat being produced by the weaving machine. A very colorful fabric can be produced when using a multi-colored warp and up to 16 different colors of filling yarns.



Slide 20

Jacquard Shedding Video

Notice the different colors of warp and filling yarns being woven into this jacquard fabric. When a given color is needed on the technical face, that colored yarn will be lifted by the jacquard head and when that color is not needed on the fabric face, it will be lowered and hidden on the technical back of the fabric. This machine employs an electronic jacquard where the design can be developed on a computer and when approved, downloaded to the weaving machine. The design of this fabric has been changed to show the wide variety of patterns that can be formed. At the front of this machine is an off-loom take-up system where the fabric can be inspected for defects before forming a fabric roll. On top of the framework is the jacquard head. Below it the draw cords which are attached to individual heddles. The back view of the machine shows the warp yarns going through the drop wires and heddles. The side view shows the filling being inserted and the subsequent forward motion of the reed for beat-up. Observe how the lifted warp yarns change in color as the given design is produced.



Slide 21

Filling Insertion

Shedding provides an opening whereby the filling yarn can be inserted in front of the reed. As it is inserted, some warp yarns are above the filling and others below it. The woven design dictates which warp yarns rise above each filling yarn. The filling yarns are inserted in a consistent, uniform manner, determined by the loom speed and the picks per inch in the fabric which in turn is determined by the rate of fabric take-up on the machine. The number of picks per inch determines the pick density of the fabric. The forward motion of the reed places the filling yarn in the fabric. Other than selecting different types of filling yarn or different colors to be inserted, the filling insertion has very little to do with the fabric design. The order and pattern of lifting and lowering the warp yarns is the main factor controlling the fabric design. There are basically five methods of filling insertion.



Slide 22

Shuttle Loom

In the late 1940’s and early 50’s, the shuttle loom was the “Cadillac” of weaving machines. It had many iron, wood, and leather parts. The upper right portion of the picture shows that this machine has dobby shedding motions with the use of a chain containing wooden bars with steel pegs inserted. This loom would run in the range of 150 to 200 picks per minute.



Slide 23

Draper Shuttle Loom

The diagram of the Draper shuttle loom provides a good view of the shuttle coming in contact with the picker stick. The shuttle must be boxed properly so that it will fly through the open shed of the warp yarns and not up through the top warp shed. Notice the carousel-looking device in the top right portion of the picture. This device holds a supply of quills which will be inserted into the shuttle when needed in order to constantly provide a supply of filling yarn to be woven.



Slide 24

Features of Shuttleless Weaving• Larger Filling packages

• Unidirectional pick insertion

• Higher pick insertion rates

• Weft feeders

• Special selvage attachments

• Quieter and safer operation

• Less machine vibration

• Demands higher quality yarn therefore better slashing, warping and yarn packaging

• Fewer fabric seconds

• Downtime is more costly

• Less power per unit of fabric made

Today’s shuttleless weaving machines have features very different from the shuttle looms. The filling supply is on much larger packages of yarn rather than small quills. Filling is inserted in one direction only with each filling yarn being cut at both sides of the fabric. The rate of filling insertion is much higher on these machines, ranging from 300 to over 1000 picks per minute. Weft yarn feeders are employed in order to maintain a constant tension on each pick. With the technology used in these machines, fabric defects were reduced as better quality yarn had to be supplied to meet the demands of higher speeds. Downtime of these machines is more costly as more production will be lost per unit of time the machine is not running. Less power is needed per unit of fabric made.



Slide 25

Weft Yarn Feeders

The weft yarn will typically leave the filling yarn package and be tensioned before going onto the feeder device. The feeder allows a certain amount of yarn to be stored and then fed into the weaving machine. Thus yarn is always available for the next pick insertion. The rate of filling insertion can be very high, normally ranging from 1200 to 2200 meters per minute, depending on the method of insertion and the machine width. The filling yarn can be unwound from the feeder in a clockwise or counter-clockwise manner, determined by the twist direction in the yarn. There will be a different feeder for each color or type of filling yarn being used. This feeder is running a black filling yarn.



Slide 26

Types of Rapier Systems

There are various types of rapier machines. The original machines used one single rigid rapier and proved not to be any more productive than the shuttle looms. The idea was developed to use double rapiers that could meet in the middle of the weave shed and hence cut in half the time needed to insert each pick. A giver rapier picks up the filling yarn and delivers it midway across the fabric width. At this point the taker rapier grips the yarn as it is exchanged between the two rapiers. As the taker rapier finishes the insertion distance, the “giver” is free to return and grip the next filling yarn to be inserted. If the rapiers remain rigid upon leaving the weave shed, then they are classified as rigid rapiers, and if they flex similar to a tape measure take up when leaving the weave shed, then they are classified as flexible rapiers. Today, there are a few machines using telescopic rapiers. They extend out like the lens on a telescope in order to insert the filling.



Slide 27

Rapier Filling Selection

Each weft yarn is threaded through a filling finger. A given filling finger is lowered when the yarn it is controlling is selected to be inserted. The selection action can be either mechanical or electronic.



Slide 28

Filling Selection Animation

This animation highlights how different colors of yarn can be selected before inserting them into the weave shed. Filling fingers have eyelets through which the yarn is threaded and the machine is programmed for each finger to be activated when that particular color or type of yarn is needed. The yarn is picked up by the left-hand rapier and delivered to the right-hand rapier. The left-hand rapier then moves back to pick up a different filling yarn to be inserted for the next pick in the fabric.



Slide 29

Filling Selection Video

This video of a rapier machine shows the action of the filling fingers and a number of feeders for supplying various colors and types of filling yarn. Each feeder is fed yarn from a yarn package, and from the feeder, the yarn enters the selection devices. This machine has eight filling feeders; therefore, eight different types or colors of yarn can be used. Some machines have as many as 16 filling feeders. From the view at the back of the machine a black yarn and a white yarn are seen being inserted alternatively. Rapiers of this type have the capability of inserting multiple filling yarns at one time. Rip-stop fabrics are a good example of inserting 2, 3, or even 4 yarns at one time to provide the heavy lines that you see in these fabrics. The multiple yarns in the same pick position should keep a rip or tear in the fabric from getting larger.



Slide 30

Single Rigid Animation

Notice how a single rigid rapier makes an insertion and then moves back across the weaving machine empty-handed. This wasted motion created the need to have double rapiers which, in a sense, doubles the fabric production.



Slide 31

Double Rigid Animation

The double rigid rapier action tends to double the loom speed. Notice how, on this type of rapier demonstration, the left-hand rapier does not let go of the filling yarn until the right-hand rapier has a positive grip on it. Cam-driven levers are used, as shown here, to open the gripper heads in order to receive and/or give up the yarn. Machine timing must be very precise so the filling exchange will take place smoothly with no dropped picks.



Slide 32

Double Rigid Rapier Video

This double rigid rapier machine is running with a jacquard head enabling it to weave a very intricate woven design. The giver rapier is located on the left side of the machine where all the filling yarn packages are located. The slow motion action shows a view of the opening levers and the associated exchange of the filling yarn. At this point, the reed moves forward and pushes the given pick into the fabric fell. The rapier machines are the most flexible of all the filling insertion methods. Rapiers can handle any type of yarn from very fine to very heavy, very smooth to slubby and even to the point of being able to weave steel wire for screens and other applications.



Slide 33

Double Flexible Animation

The double flexible rapier machines take up less weave-room space since the rapiers flex as they retract from the weave shed. The rapier tape coils around a large tooth-like wheel or sprocket.



Slide 34

Flexible Rapier Video

The filling yarn supply for this flexible rapier machine is delivered to the filling feeder which in turn tensions the yarn and stores it for immediate use. Multiple coils of yarn are wound onto the feeder. Brush rings are used to help tension the yarn as it is pulled from the feeder. From the feeder the yarn goes into the weave shed after being picked up by the left-hand rapier. Feeling fingers select the given yarn to be inserted. The machine is running in slow motion and then goes into normal speed.



Slide 35

Projectile and Guide

Projectile filling insertion utilizes a bullet like device which grips the yarn and shoots it across the weave shed. To prevent the projectile from escaping from the machine, metal guides are used which are closely spaced across the width of the weaving machine. On modern projectile machines, the projectile is made from graphite or some composite material, whereas on older machines the projectile is metal. Projectiles can be various weights in order to accommodate different yarn counts. The range of yarn counts and the yarn types will not be as wide as it is on rapier machines.



Slide 36

Projectile Photo

The projectile seen is entering the guides with the yarn trailing behind. As the reed moves forward the guides move downward, allowing the filling to move out of the guides for placement in the cloth fell. On many machines a small drop of oil is put on the projectile before insertion in order to reduce the friction between the projectile and the guides. This increases the wear life of the projectile and guides. The speeds of these machines are somewhat lower than rapier machines, all things being equal.



Slide 37

Projectile Animation

This animation highlights the projectile gripper opening up to receive the filling yarn. A torsion bar is twisted to store up energy. When this energy is released, a connected lever strikes the projectile and propels it across the weave shed. Once the projectile finishes its flight through the guides, it is placed on a conveyer chain which transfers it back to the other side of the weaving machine. There will be a projectile approximately every ten inches on the conveyor chain ensuring one is always available for insertion.



Slide 38

Air Jet Diagram

The air jet diagram at the top illustrates an earlier type of guide system found on air jet machines. The guide system was separate and not part of the reed. The structure of the air guides was designed so that the air would not disperse quickly and lose its pressure. The earlier machines were narrow with the use of only a single main nozzle. To weave wider fabrics, intermediate or sub nozzles (sometimes called relay nozzles) were placed on the machine. These were programmed to inject air at timed sequences that keeps the pick moving across the weave shed. Latest air jet machines use a profile or tunnel reed where the air guide system is built into the reed as seen in the bottom diagram.



Slide 39

Air Jet Reed Video

This close-up of a profile reed illustrates how the filling yarn enters the tunnel provided in the reed, and how, at this point, the warp yarns are separated into an upper and lower shed arrangement. Also notice the first relay nozzle. Air jet weaving demands good warp yarn preparation. Because air can be easily misdirected, the weave shed must be free of any sticking or tangled warp yarns. Good warping and slashing operations ensure that no wild yarn or excessively hairy yarn will impede the flight of the filling yarn across the width of the machine. Many air jet filling stops are warp-related, meaning that the cause of the stop was related to the quality of the warp yarn and not related to the quality of the filling yarn. The force of air needed to pull the yarn off of the filling feeder varies according to yarn type. Ring spun yarn is typically hairier than open end yarn and therefore higher air nozzle pressure is generally needed to successfully remove the ring yarn from the filling feeder. Filament yarns tend to be smoother and slick, therefore, less air nozzle pressure is needed. Textured filament yarns are more air-friendly than flat filament yarns, since there is more yarn surface friction to interact with the air. Very slick flat filament yarns are a challenge to weave as filling yarn on air jet machines due to a tendency to slough off the package.



Slide 40

Air Jet Animation

The progressive action of the relay nozzles as the filling yarn moves through the weave shed is shown in this animation. The relay nozzles are normally micro-processor controlled to ensure precise timing of the air injection.



Slide 41

Air Jet Nozzles

This air jet machine photograph shows the placement of the relay nozzles and the fine openings on the tip of the nozzles. The openings always point in the direction that the filling yarn is traveling. During beat-up of the filling yarn, the relay nozzles move out of the way and do not interfere with pick placement in the fabric.



Slide 42

Air Jet Weaving Machine Video

Air jet machines provide the fastest method of filling insertion. This particular machine is running at 680 picks per minute. Other machines run upwards of 1200 picks per minute and higher depending on the machine width. To gain a perspective on the speed of the weaving motions taking place, consider a machine running a modest speed of 600 insertions per minute. How many is that per second? That means by the time you count “one thousand one,” the machine has inserted 10 picks. And it has also performed shedding and beat-up 10 times in that one second. Even though this seems fast, remember that only one filling yarn is being inserted at a time which is only a small fraction of the total length of fabric being produced. Remember that weaving is a single-phase process. Compared to knitting, which is a multiple-phase process, weaving is slower. At the end of this video, you can see where the yarn leaves the air nozzle, enters the weave shed and passes through the tunnel reed. Lastly, you can see where the inserted pick would end up on the other side of the machine.



Slide 43

Water Jet Animation

Water jet weaving uses a pulsating stream of water to insert each filling yarn. Therefore, there are limitations as to the type of yarn that can be run on these machines. Only yarns containing hydrophobic fibers can be used because of the need to dry the fabric prior to forming a fabric roll. Fabrics containing fibers like cotton, wools and rayon would not be recommended for these machines. The most common use of water jet machines is in the production of mattress ticking or fabric making up the outer surface of a mattress. These fabrics are typically made from polyester and nylon filament yarns. The machine parts have to be non-corrosive. The water temperature needs to be cool for best interactions with the yarn.



Slide 44

Water Jet Machine Video

This water jet machine is running at 1100 picks per minute. It is producing a polyester filament fabric. A rubber-coated granular surfaced roller helps to pull the fabric through the weaving elements without the fabric slipping. The narrow slit seen under the warp yarn is a vacuum slot used to suck water out of the fabric prior to roll-up. The water nozzle is on the left side of the machine, so the filling travels from left to right. A close-up of the water nozzle and a filling yarn tensioning device can be seen. Water pulsates from the nozzle and this burst of water transports the filling yarn across the machine. In the video everything looks blurred indicating that the machine is running at a very high speed. When a strobe light is used, the movement of the reed back and forth, as the filling is placed or beat-up into the fabric, is seen. Notice, too, how quickly the shed is being formed before each insertion. The speed of water jet weaving is faster than shuttle, projectile or rapier weaving but typically not as fast as air jet weaving.



Slide 45

Beat-Up Motion



Slide 46

Reed Functions

The reed is the primary element used in the beating of the filling yarn into the fell of the cloth. However, the reed has other functions as well. It aids in positioning the warp yarns across the width of the weave shed. Each slot or opening in the reed is called a dent. Through each dent a given number of warp yarns will be drawn. Some fabric designs may call for 2 yarns per dent, some 3, some 4 and some a variable number in each dent in a specific sequence. This is called an irregular reed plan. Whatever this number, it will be referred to as the reed plan. Different reed plans work best for a given weave design. Occasionally, if a fabric has faint streaks in the warp direction, the reed plan can be changed to remove the streakiness.



Slide 47

Air Jet Reed

As mentioned earlier, the reed used in air jet weaving has a tunnel-like profile which provides a path for the air and yarn to follow. These are more expensive than flat reeds which are used in all other methods of filling insertion. The reed shown here is only a small section of a full-width reed.



Slide 48

Reed Number

Reed number is the number of dents per inch in the reed and is usually stamped on the reed. The picture shows a very coarse reed on the left with seven dents per inch and a very fine reed shown on the right. The coarse reed would handle heavy or thick yarns for weaving heavier fabrics or more open fabric if desired. The fine reed would handle finer yarns for weaving lighter weight fabrics. The fine reed fabric would tend to be tighter in construction, more warp yarns per inch. The reed number can be calculated by dividing the ends per inch in the fabric by the ends per dent in the reed. Different fabric designs require different reed numbers. A typical weave plant could have a fairly large inventory of reeds.



Slide 49

Beat-up (Rigid Rapier)

Once the filling yarn is inserted, the reed beats it into the fabric fell. The beat-up can be an indication of over constructing a fabric, meaning too many yarns are inserted per given space in the fabric. If this happens, the beat up motion will be loud with a shaking or vibrating machine. Weaving machines typically vary in robustness. Very robust machines are used for manufacturing heavier fabrics, performing a very forceful beat-up. Less robust machines are used for manufacturing lighter weight fabrics, performing a more subtle beat-up. Beat-up can occur before the top and bottom shed cross (shed crossing) or after they cross, depending on the type of fabric being woven. Some machines have a special sequence where beat-up will not occur until 3 to 5 picks have been inserted. An example of this is in the production of terry woven fabrics. A video of this type of beat up will be shown later.



Slide 50

Warp Control OverviewLet Off:

• Controls rate of yarn removal from the warp beam.• Controls tension of warp ends.

Take-Up:

• Determines the picks per inch in the fabric• Determines woven fabric production rate

The fourth and fifth primary weaving motions are let-off of the yarn from the loom beam and take-up of the fabric after it has been woven. A consistent let-off ensures a constant warp yarn tension, and a consistent take-up ensures a constant number of picks per inch in the fabric. Some newer weaving machines have a variable take-up system which allows the insertion of variable picks per inch in the fabric as the machine is running. Therefore, the pick density varies in different parts of the weave design. Fabrics with lower picks per inch have a higher productivity because the rate of take-up of the fabric is higher. Of course, the opposite is true of fabrics with a higher pick density.



Slide 51

Review – What Motions

What primary weaving motions do you see in this video? What is the required sequence of the primary weaving motions? If you answered shedding, filling insertion, and beat-up in that order you would be correct.



Slide 52

Production CalculationsCalculating linear yards of fabric produced on a weaving machine per hour of operation can be done using the following formula:

Linear Yards/Hour = (picks per min. / picks per in.) x (60 min. per hr. / 36 in. per yd) x loom efficiency (%)

Linear Meters/Hour = (picks per min / picks per centimeter) x (60 min. per hr. / 100 cm per meter) x loom efficiency (%)

Square Yards/Hour = Linear Yards Per Hour x Fabric Width (Yds.)

Square Meters/Hour = Linear Meters Per Hour x Fabric Width (Meters)

Rate of Filling Insertion (Yards/Min) = Loom Speed (Picks/Min) x Loom Width (Yds.) x Loom Efficiency (%)

Rate of Filling Insertion (Meters/Min) = Loom Speed (Picks/Min) x Loom Width (Meters) x Loom Efficiency (%)

Common formulas used in weaving production calculations are shown in the accompanying slide. Examples are given for both English and Metric systems. The following slides illustrate the use of these formulas.



Slide 53

Example 1

What are the linear yards of fabric produced on a machine running 650 picks per minute, inserting 58 picks per inch, and operating at a 92% efficiency?


Linear Yards/Hour = (650 picks per min. / 58 picks per in.) x (60 min. per hr. / 36 in. per yd) x .92 loom efficiency

Answer: 17.2

You can test your understanding of the concepts presented by answering the following questions. For example: What are the linear yards of fabric produced on a machine running 650 picks per minute, inserting 58 picks per inch, and operating at 92% efficiency? The calculations are shown in red.



Slide 54

Example 2

What is the rate of filling insertion in a loom running 720 picks per minute with a width of 2.5 meters at 93% efficiency?

Rate of Filling Insertion (Meters/Min) = Loom Speed (Picks/Min) x Loom Width (Meters) x Loom Efficiency (%)

Rate of Filling Insertion (Meters/Min) = 720 (Picks/Min) x 2.5 (Meters) x .93 Loom Efficiency

Answer: 1674 meters of filling inserted per minute

In this example: What is the rate of filling insertion in a loom running 720 picks per minute with a width of 2.5 meters at 93% efficiency?



Slide 55

Question 1

Using the square meters/hour formula, determine which of the following machines would be more productive.

A. A two meter wide rapier machine running 475 picks per minute at 90% efficiency and inserting 20 picks per centimeter

B. A 1.5 meter wide air jet machine running 675 picks per minute at 90% efficiency and inserting 20 picks per centimeter

Note: 100 centimeters in 1 meter

Try these examples on your own. Using the square meters/hour formula, determine which of the following machines would be more productive.



Slide 56

Question 1 Solution

This is the solution for Question 1. There is no narration for this slide.



Slide 57

Question 2

Reviewing the factors in the formulas for calculating the linear yards or linear meters that can be produced per hour on a weaving machine, what changes in these factors could be made that would increase weaving production?



Reviewing the factors in the formulas for calculating the linear yards or linear meters that can be produced per hour on a weaving machine, what changes in these factors could be made that would increase weaving production?



Slide 58

Question 2 AnswerReviewing the factors in the formulas for calculating the linear yards or linear meters that can be produced per hour on a weaving machine, what changes in these factors could be made that would increase weaving production?



Answer

1. an increase in picks per minute

2. a decrease in the picks per inch or picks per centimeter

3. an increase in loom efficiency

The answer to the problem is by increasing the picks per minute, decreasing the picks per inch and increasing the loom efficiency. Each one of these would result in an increase in loom productivity.



Slide 59

Basic Woven Designs



Slide 60

Plain Weave

The plain weave is the oldest, simplest, and most widely used weave design. This, like all other designs, can be illustrated on a grid as shown on the right of this slide. Occasionally this grid is called point paper or point graph which can be shown on a computer screen as part of a CAD system or as a hard copy. Each vertical column of blocks in the grid represents an individual warp end (red yarn in this case) while each horizontal row of blocks represents a filling, pick or weft yarn (white yarn in this case). While following the first warp end in the grid, notice that the first block is filled in and moving vertically the next block is left blank. This pattern continues indicating that the first warp end weaves over the first pick and then under the second pick, over the third pick, under the fourth pick, etc. So any time a block is filled in, the warp yarn is over the filling at that point. Any time a block is left blank or white, the warp yarn is under the filling yarn at that point. Notice that the second warp yarn in the grid diagram weaves opposite from the first warp yarn. This is characteristic of the plain weave design indicating that this weave has more cross-over or interlacing points than any other weave design. The diagram to the left of the grid represents the actual weaving of the warp and filling yarns which matches with the representation in the grid diagram. Notice one repeat of the plain weave involves two warp yarns and two filling yarns as shown at the top of the slide. Notice, also, the crimp of the warp yarns and the crimp of the filling yarns in the cross-sectional drawings.



Slide 61

Plain Weave

This is a normal and magnified view of a plain woven fabric. Each warp yarn (the vertical yarn) is going over and then under each filling yarn (the horizontal yarn). As previously mentioned, this weave design yields the most interlacing points that can occur in a woven fabric. Thus, compared to other weave designs, this design creates the stiffest fabric with the least amount of drape, all other things being equal. However, the fabric is very stable with good resistance to skewing, picking and snagging. When a tear strength test is conducted, only one yarn at a time is broken in order to propagate a tear. Thus, plain weave fabrics have relatively lower tear resistance compared to other weave designs, again all other factors being the same. The tensile strength of this fabric, or force needed to pull the fabric at two ends and rupture it, depends upon the number of yarns per inch in the fabric construction plus the linear density of the yarns. More dense fabrics tend to have a higher tensile strength because there are more yarns to share the load placed upon the fabric.



Slide 62

Balanced Plain–Woven Fabrics

• batiste• buckram• calico• cambric• canvas• challis• chambray• cheesecloth • crash• crepe de chine• cretonne• crinoline duck

• flannel• gauze• georgette• gingham• lawn• muslin• organdy• percale• seersucker• sheeting• voile

Balanced plain-woven fabrics essentially have the same threads per inch for the warp yarns and filling yarns. In addition, the yarn sizes for warp and filling are approximately the same. A few names of specific balanced plain-woven fabrics are batiste, canvas, cheesecloth, flannel, gauze and seersucker. It is important to remember that fabrics are given specific names depending on weight, yarn structure, color-and-weave effect and finishes.



Slide 63

Unbalanced Plain–Woven Fabrics

• broadcloth

• poplin

• taffeta

• faille

• repp

• grosgrain

• bengaline

• ottoman

Unbalanced plain-woven fabrics are fabrics in which the number of warp yarns and filling yarns per inch are very different, and the yarn sizes can be very different as well. This unbalanced nature of the fabric creates crosswise rib effects. A few names of specific unbalanced plain-woven fabrics, given according to increasing prominence of the crosswise rib, are broadcloth, poplin, taffeta and repp.



Slide 64

Twill Characteristics• Diagonal lines running at angles varying between 15 and 75 degrees

• Denoted by using numbers above and below a line

– Example : 2/1 and 1/2

• Repeat represented by the addition of these numbers

– Example: 2/1 and 1/2 repeat on 3 ends and 3 picks

• 2/1 and 3/1 are examples of “warp face twills”

• 1/2 and 1/3 are examples of “filling face twills”

• 2/2 , 3/3 and 4/4 are examples of “balanced twills”

• Twills can also be characterized as:

– Left Hand twills, Right Hand twills

– Steep Twills

– Reclining Twills

– Broken Twills

– Pointed-double pointed twills

Fabrics with a twill design are characterized by diagonal lines either rising to the left (called left-hand twill) or rising to the right (called right-hand twill) on the face of the fabric. These diagonal lines can vary in angle from 15 to 75 degrees. Most regular twills have line angles of approximately 45 degrees. Twill fabrics with twill line angles greater than 45 degrees are referred to as steep twills with a common example being Cavalry twills which contains a pronounced double twill line of 63 degrees. Reclining twills have twill lines at an angle less than 45 degrees. Twill weaves are denoted by a number system. The top number represents how many filling yarns a given warp yarn goes over and the bottom number represents how many filling yarns a given warp yarn goes under. So in a 2 over 1 or 2/1 twill weave, each warp yarn goes over two filling yarns and then under one filling yarn, over two, under one, so forth. In a 1 over 2 twill weave, each warp yarn goes over just one filling yarn and then under two filling yarns. How would you describe a 3 over 1 twill? Each warp yarn weaves over three filling yarns and then under one filling yarn and so forth. Each time the top or first number is larger than the bottom or second number, the fabric is a warp face twill. Each time the top or first number is smaller than the bottom or second number, the fabric is a filling face twill. When both numbers are the same, such as in 2 over 2 twill, the fabric is called a balanced twill.



Slide 65

Twill Fabric TypesWarp-Faced Twill Fabrics

• cavalry twill• covert cloth• denim• drill• dungaree• gabardine• jean• whipcord

Balanced Twill Fabrics

• foulard • herringbone• houndstooth• serge

A few specific warp-faced twill fabrics are denim, gabardine and whipcord. Two of the most common balanced twill fabrics are herringbone and houndstooth.



Slide 66

Effect of Yarn Twist

As illustrated in the accompanying chart, any time the warp yarn has a twist direction opposite from the twill direction, the twill line will be higher or more prominent. In this case, the fabric seems to be softer. Given that all open end yarns can only be manufactured with z twist, which fabric twill direction would produce fabric with a more raised twill line and a softer hand? The answer, a left-hand twill.



Slide 67

Whip Roll or Back Rest Effects

Another factor influencing the height of the twill line in a twill weave fabric is the height of the back rest or whip roll. A lower setting produces a low warp twill effect and a higher setting produces a higher warp twill effect. The higher the whip roll, the lower the warp yarn tension in the top shed. Since the top shed yarns are on the technical face of the fabric, the reduced yarn tension produces a high warp twill effect.



Slide 68

2/1 Twill

In a 2 over 1 fabric design, each warp yarn weaves over two filling yarns and then under one filling yarn. Adding these numbers together indicates how many warp yarns or ends are in the weave repeat and how many filling yarns are in the weave repeat. In this case, three warp yarns and three filling yarns are one repeat of the weave design. The diagram at the top of the slide shows two repeats of the weave design whereas the grid drawing shows one repeat. This weave design yields different fabric properties from what was discussed with the plain weave. For example, when tearing the fabric along the warp direction, two filling yarns are being broken at a time to propagate the tear, not one as in the plain weave. In effect, two yarns bunch together to offer a higher resistance to tearing. Due to less crimping of the yarns, the tensile strength of a twill weave fabric tends to be higher, all things being equal. With fewer interlacings in this type of fabric, the fabric drape is better, again all things being equal.



Slide 69

2/1 Right Hand Twill

The magnified view of a 2 over 1 right hand twill shows that each warp yarn goes over two filling yarns and then under one filling yarn. The twill line rises to the right. Notice how each successive warp yarn, going from left to right, begins its pattern of “over two and under one” one pick above the previous warp yarn. This produces a stair-stepping effect which creates the twill line angle. When warp yarns are increased in number per inch in the fabric construction, the twill line will be steeper.



Slide 70

1/2 Twill

The 1 over 2 right hand twill weave also repeats on three ends and three picks. However it is a filling face twill, since there is more white yarn showing on the fabric face than red yarn. This weave might be chosen in order to highlight a novelty or fancy filling yarn being used. Is this fabric the same as taking a 2x1 twill and turning it over? The answer is no. What is the difference? The twill line will be right hand on the face side and left hand on the back side.



Slide 71

1/2 Left Hand Twill

In this 1 over 2 left hand twill select any dark blue warp yarn and follow it in the fabric, it goes over one light blue filling yarn and then under two. The twill line in this case rises to the left and the fabric is called a left-hand twill weave. Notice that more filling yarn shows on the fabric face compared to the amount of warp yarn showing. Also notice that the filling yarn is coarser, greater linear density, than the warp yarn and contains lower yarn twist. The filling yarn also appears to be more hairy.



Slide 72

Balanced Twills

The 2x2 twill weave design is the most common balanced twill design used. This weave repeats on four ends and four picks in the fabric. There is an equal number of blocks filled in and left blank in order to illustrate this weave pattern. Thus, there is an equal amount of warp yarn and filling yarn showing on the face of the fabric. As mentioned previously, if the same yarn twist direction is used in both the left hand and right hand twill fabric, the appearance and hand of the fabric will not be the same.



Slide 73

2/2 Left Hand Twill

In this magnified view of a 2 over 2 left hand twill fabric, the yarn twist direction is “Z” which produces a raised twill line that is very visible on the fabric face as seen in the unmagnified fabric swatch. Following each warp yarn, the end weaves over two filling yarns and then under two filling yarns. Moving from right to left, this 2 over 2 sequence is repeated as you advance up one pick on each successive warp yarn. As mentioned earlier, this stair-stepping effect produces the left-hand twill line.



Slide 74


The 2 over 2 right-hand twill fabric also utilizes “Z” twisted yarn. Because of the “Z” twist the twill line is flatter and therefore not as visible on the fabric face as seen on the unmagnified view of the fabric.



Slide 75

3/1 Twill

3x1 twill fabrics have longer floats; the warp yarns weave over a higher number of filling yarns than previously discussed. Each end weaves over 3 picks before going under 1 pick. The top right hand sketch represents one repeat of this weave occurring on 4 ends and 4 picks. The top left hand sketch shows two repeats of the 3x1 weave design using 8 warp yarns and 8 filling yarns. There is a significantly greater amount of red warp yarn showing on the fabric face and very little white filling yarn.



Slide 76


The 3 up 1 down right-hand twill design is commonly used in bottom weight denim fabrics. This denim fabric sample contains indigo blue warp yarns and naturally undyed filling yarns. Therefore, the fabric face is predominantly blue. If the fabric was turned over, it would be predominantly white. The twill line is wider than it is in 2x1 and 2x2 weave designs viewed earlier. This is because of the longer floats.



Slide 77

3/1 Left Hand Twill

As in the other twill fabrics, 3x1 twill fabrics contain yarns twisted in the “Z” direction. Therefore, the left-hand twill has a more raised twill line. In the 3x1 twill with fewer interlacings, more filling yarns can be inserted to make a denser and heavier fabric. These heavier bottom weight fabrics are mostly 3x1 twills while top weight or shirting twills are 2x1 and 2x2 designs.



Slide 78

Herringbone

Herringbone is an excellent example of a broken twill design where the twill line is discontinuous, alternating between right hand and left hand. With the herringbone fabric, the points where the right hand and left hand twill lines meet form a staggered or broken point. As illustrated on the point paper or grid sketch, the weave pattern repeats on 8 ends and 4 picks. The DID notation for different weave designs stands for drawing–in–draft. In the DID, each horizontal row of blocks represents a single harness. Each vertical column of blocks represents a warp yarn or end. Therefore, warp yarn 1 in the weave design is drawn through harness 1, warp yarn 2 through harness two, warp yarn 3 through harness 3, and warp yarn 4 through harness 4. Since warp yarn 5 weaves the same as warp yarn 2 in the weave design sketch, it will be drawn through harness 2. As can be seen, warp yarn 6 weaves as warp yarn 1, 7 as 4, and 8 as 3. Therefore only 4 harnesses are needed to weave this design. However, if there is any crowding of the warp yarns due to higher sley fabrics, the number of harnesses must be some multiple of 4, such as 8 or 12. The CP notation stands for chain plan. In the CP, each horizontal row of blocks represents a filling yarn or pick while each vertical column of blocks represents a harness. For example, on pick number 1, harness 1 is up (illustrated by the shaded block), harness 2 and 3 are down (illustrated by the un-shaded blocks or white blocks, and harness 4 is up (illustrated by the shaded block). One can follow each successive pick and know which harnesses are up and which are down as each pick is inserted into the weaving machine. Using these two instructions, drawing-in-draft and chain plan, any specific weave design can be set up on a weaving machine. The only remaining piece of information needed is the reed plan which indicates how many warp yarns are drawn through each dent or slot in the reed.



Slide 79

Chevron

The chevron twill has a different design and drawing-in-draft, but the same chain plan resulting in a design where the right and left twill lines come to a direct point and not a staggered point as in the herringbone twill. Therefore, chevron twills are not true broken twills. In a true broken twill, at the point where the twill direction changes, if the warp is on the surface, the next thread on the surface is the filling, forming a clear break. This is not true with pointed twills such as chevrons. There are many other twill variations that can be developed by blending the use of right and left hand twill lines. Frequently the twill line is broken or displaced to the right or left but continues in the same direction. This is another way to form a broken twill design.



Slide 80

Satin Weave Definition

The terms satin and sateen are sometimes confused. Satin is the weave. Sateen is a satin weave fabric constructed from yarns other than silk. A satin fabric is a satin weave constructed from silk. Satin weaves are designated by the number of harnesses that are required to weave them. Each end of the repeat weaves differently; therefore, the number of ends per repeat will be the same number of harnesses required to weave the fabric. Satin may be made by using as few as 5 harnesses or as many as 16 harnesses.

There are different definitions for satin and sateen fabrics around the world. The definition most often used states that a satin fabric is a satin weave fabric woven with silk yarns and a sateen fabric is woven with yarns other than silk. However in some parts of the world satin weave is when filament yarn is used and sateen weave is when spun yarn is used. Other parts of the world use the term satin to denote when the warp yarn floats in the fabric and use the term sateen to denote when the filling yarn floats in the fabric. Satin weaves are described by the number of harnesses being used which will be the same as the number of ends per repeat of the design. Five, seven and eight harness satins are the ones most commonly woven.



Slide 81

5 Harness Sateen (filling face)

This diagram represents a 5 harness sateen weave by some definitions because the filling yarn is floating and is also referred to as a filling face sateen. As can be seen, there is very little warp yarn on the face. Notice that the weave repeats on 5 ends and 5 picks. This weave design will create fabric with a very smooth and lustrous surface but will have low resistance to picking, snagging, and skewing. Seam slippage would be higher. Tear strength would be very good since multiple yarns would be free to bunch together and resist the propagation of a tear. The counter is a number that is used to insure that no interlacing points are touching. Using 2 as a counter and starting from any interlacing point go over to the next warp end and count up 2 picks. This is where the next interlacing point will be placed. From here you go through the same routine to establish each interlacing point in the weave repeat. Of course, when using 3 as a counter, you move directly over to the next adjacent end and count upward 3 picks for the next interlacing point. The use of 2 and 3 in this case indicates that they are pick count.



Slide 82

5 Harness Sateen (warp face)

To some people, this would be defined as a satin weave because the warp floats. If non-silk yarns are being used, others would refer to this design as a warp face sateen weave. Being a warp face design, more warp yarn is showing on the fabric face than filling yarn. Warp face satins tend not to be as soft as the filling face satins because of a higher yarn twist level typically found in the warp yarns.



Slide 83

Satin Fabric Uses

• Apparel

• Bridal wear

• Fabric linings

• Upholstery fabrics

Satin fabrics are luxurious, more formal fabrics. They are frequently used for evening apparel, bridal wear, fabric linings and as upholstery fabrics for elegant settings. Satin fabrics can be designed with wind-proof properties as in wind-breaker jackets and coats. Types of satin designs are often used in the background or base fabrics for tapestries and other fabrics with decorative designs.



Slide 84

5 Harness Sateen (warp face)

Notice how the warp yarn floats in this warp face sateen fabric. Cotton spun yarn is woven in both warp and filling directions. Spun yarn satin and sateen fabrics will not be as lustrous as filament yarn satin and sateen fabrics due to the hairiness of the spun yarn scattering reflected light.



Slide 85

Basket Weaves

Many other weave designs are based on one or more of the previously discussed basic weave designs. Basket weaves are derivative of the plain weave. Instead of weaving individual warp and filling yarns, multiple yarns are woven in some sequence or repeat. If two warp and two filling yarns weave alike, then the weave is named 2x2 basket weave. If three warp and three filling yarns are weaving alike, then the basket weave is named a 3x3. This tends to be a looser weave than the basic plain weave with a higher resistance to tearing but less resistance to sheer, seam slippage, snagging and picking. In apparel, many basket weave fabrics are used for suits, such as hopsacking, and sportswear, such as sailcloth. Other uses include slipcovers for furniture, house awnings and boat covers. Monk’s cloth is also used in home furnishings.



Slide 86

2x2 Basket Weave

The texture of this weave is generally coarser with a more squared pattern look. Notice how the interlacing of the yarn creates open space or porosity. The term cover factor is the percentage of space covered by the yarns. Every woven fabric will have a certain cover factor based upon the weave design, yarn sizes used and the fabric count. This example would have a lower cover factor due to the openness of the fabric.



Slide 87

Irregular Basket Weaves

When numbers denoting the weave design are not identical, it is described as an irregular basket weave design as illustrated in this slide. This results in a more variable textured appearance. The weave repeat for these designs will be the summation of the numbers used to describe the weave design. For example, the 3x2x1x1 would repeat on 7 warp yarns and 7 filling yarns.



Slide 88

Oxford

Another derivative of the plain weave is the oxford weave. The oxford weave can be described as a modified basket weave. Supposedly, it was originally made at a Scotch mill and named after Oxford University. In this weave design, two warp yarns weave together, both going over and under individual picks. A regular oxford weave has approximately twice the number of ends per inch as picks per inch. The filling yarn is much coarser, with much lower twist than the warp yarn. Many oxford shirting fabrics utilize dyed warp yarns and natural filling yarns. This weave design is also used in sportswear.



Slide 89

Oxford

The finer warp yarn and coarser filling yarn reveals that this is a regular oxford designed fabric. Notice that the cover factor is higher using this fabric design compared to the basket weave sample previously viewed. The fabric is not as porous. When the warp and filling yarns are finer and of the same yarn count, then the fabric is referred to as a pinpoint oxford. This fabric would be smoother and more lustrous than the regular oxford.



Slide 90

Bedford Cord

The Bedford cord design yields a fabric with cords running in the warp direction. In between the raised cords are warp yarns weaving plain weave which creates a narrow, depressed area between the cords. There is some question about the origin of the term, with New Bedford, Massachusetts claimed as the place in which it was first made and from which it derived its name. The better quality Bedford cord fabrics have two-ply yarns in the warp, to form the face, with heavy single or ply yarns for the backing which serve as stuffer threads along the back of the cloth. Single yarns are used in the inexpensive quality Bedford cords without stuffing ends, in which the cord or wale effect is formed only by the weave.



Slide 91

Bedford Cord

Notice the raised warp yarns floating on the fabric surface of this Bedford cord fabric sample followed by other warp yarns weaving plain weave between adjacent cords. Bedford cord fabrics are strong and wear well and are suitable for upholstery, suits, slacks, sportswear, shirts, riding habits and work clothes.



Slide 92

Pique

Woven pique fabrics have a width-wise rib pattern or filling cords. True pique is a double cloth with two warps, one fine and one heavy, and two filling yarns, one fine and one heavy (the latter is a stuffer yarn). Pique weaves are commonly used in clothing and decorative fabrics.



Slide 93

Corduroy

Corduroy is a filling pile fabric in which extra filling yarns are inserted into the fabric. These extra filling yarns float over multiple warp yarns and will eventually be cut and stand up on the fabric face to produce ribs or wales in the corduroy fabric. The name is derived from the French phrase “cord du roi”, meaning “King’s cord.” The design sketch at the bottom right of this slide reveals the long floats in the filling yarns that will be cut during finishing.



Slide 94

Corduroy Wales

There are two ways that the filling yarn forming the wales can be interlaced with the fabric ground. In V-wale corduroy the cut pile yarn is held only by interlacing with a single warp yarn thus forming low holding power. In the W-wale corduroy design, the cut pile yarns interlace around three different warp yarns, and thus, there is more holding power to keep the pile yarns from pulling out. The W-wale produces a corduroy fabric in which the yarns are more seperated, leaving a less dense wale than the V-wale.



Slide 95

Combination “V” and “W” Wales

To produce a wider and more rounded wale in a corduroy fabric, many times a “W-V-W” combination is utilized. The W-wales produce good fabric stability, and the taller V wales aid in forming a more rounded wale.



Slide 96

Corduroy Cutting

In finishing, needles with open slots are slid under the floating pile picks as pictured on the left. Rotating knives travel along these slots, cutting the pile picks without cutting the ground picks and warp yarns. The spacing of the needles determines the wale width and resulting wales per inch in the fabric. Fine pin wale corduroy (14-20 wales per inch) is made by passing the fabric through multiple cutting stages.



Slide 97

Corduroy

The vertical ribs or wales are readily seen in this corduroy fabric. Subsequent brushing and shearing help to produce more uniform wales on the fabric surface. Corduroy is used in men’s and women’s sportswear, dresses and children’s clothing.



Slide 98

Velvet Weaving Diagram

Velvet is classified as a warp pile fabric. As illustrated, two or more loom beams are needed. Two fabrics or a double cloth are formed, one over the other. Two filling yarns are inserted, one over the other. The pile warp provides warp yarns that weave in and out of both fabrics while the ground warp shares its yarns, some weaving in the top fabric and the remainder weaving in the bottom fabric. The pile warp yarns that connect the two fabrics together are cut by a reciprocating knife blade as the double cloth is separated at the front of the weaving machine. Thus two identical velvet fabrics come off the machine with each one having a plush warp pile surface.



Slide 99

Velvet Fabric

The fabric looks like this as it comes off the weaving machine before cutting. You can see the connecting yarns between the two fabrics and how, after cutting, two fabrics are formed, each with a plush pile surface. This particular fabric is used in the interior of automobiles.



Slide 100

Velvet Fabric Sample

The pile seen on the face of this fabric is warp yarn that has been cut. These cut yarns, like cut pile yarns in corduroy, can be held in place as a V interlacing pattern or a W interlacing pattern. The W type would be more stable and more expensive. Not to be confused with velvet, velveteen is a filling pile fabric where extra filling yarns are cut to produce a plush and soft fabric surface. Little velveteen is produced today. Density of the pile in velveteen depends upon the number of picks per inch which ranges from 175 to 600.



Slide 101

Terry Weaving Machine

Woven terry is another warp pile fabric. The bottom beam provides the ground warp while the top beam provides the pile warp. The pile yarns form loops on the fabric surface.



Slide 102

Terry Fabrics Diagram

The key to forming terry loops is in the action of the reed. To produce terry cloth, the reed will not move into beat-up position until a certain number of picks have been inserted into the fabric. Thus there remains a given length of warp yarn, without the presence of filling yarns, between the reed and the fabric fell. Then the reed moves forward to the beat-up position, beating up multiple picks and at the same time pushing up the warp yarns to form the terry loops.



Slide 103

3 Pick Terry Diagram

The most common terry weave is 3 pick terry. Three picks, the pink yarns, are inserted before beat-up occurs on the machine. Notice that two picks are under each set of loops and the third pick is used to beat up the loops. The light blue and green yarns represent the warp pile yarns that form the loops on both sides of the fabric.



Slide 104

Terry Weaving Video

Notice, as this machine is weaving, that beat-up occurs only after three picks have been inserted into the fabric. A loose or swinging reed is employed on the first two picks, and is made fast or rigid on the third pick while the pile beam is slackened so that the pile loops can be formed. As beat-up takes place, the pile warp yarns form loops on the fabric. Pile yarns can be made to form loops on the technical face and back or just on one side.



Slide 105

Multiple Height Terry Diagram

As shown in this diagram, the terry machine can be programmed to produce multiple loop heights for a sculptured design look.



Slide 106

3 Pick Terry Fabric (greige)

In this photograph of a greige terry fabric, the loops are laying down, producing a very random loop formation and poor uniformity of loop heights.



Slide 107

3 Pick Terry Fabric (finished)

In the finished fabric, after brushing and other dyeing and finishing operations, the loops are standing up, producing a more uniform and dense fabric surface.



Slide 108

Woven Crepe

Woven crepe is typically a light weight fabric, characterized by a crinkled or pebble-like surface obtained by the use of hard-twist filling yarns, chemical treatment, a crepe weave design, embossing, or by some combination of these.



Slide 109

Jacquard Fabric

This is a flat jacquard fabric where the warp yarns have been controlled in such a way to produce a large design repeat. Many woven jacquards contain dyed yarns for weaving a fancy pattern. Tapestry, brocade, damask and brocatelle all fall under the category of jacquard fabrics.