Warping and Selvedge
The arranging of yarn threads in long parallel lengths of equal tension, onto a beam in preparation for weaving.During the warping process cones of yarn are placed onto a rack called a creel. From this creel yarn passes through tension and spacing devices and through a leasing reed which separates the yarn threads and keeps them in the correct order before being wound onto a warping balloon.Selvedge means the edge of a fabric that is woven so that it will not ravel or fray.
A beam on which yarn is wound on the warping machine is called "warper's beam". A roller on which large flanges are usually fixed so that a warp may be wound on it in readiness for weaving is called "Weaver’s beam"
Types of Warping Systems
- Direct or beam warping
- Indirect or sectional warping
- Thread by thread warping
Yarns from cone packages are transfered to weaver's beam which is called warp preparation.
Beam/Warp preparation process
- Creeling and warping
- Putting: Putting is the process of placing the yarn packages in the creels in desired order, in order to make warper's beam.
Types of creeling
- Magazine Creel
- Reversible Creel
- Duplicate Creel
- Truck Creel
Direct or Beam Warping System
The winding of the total number of warp ends in full width in a single operation from creeled bobbins, either onto a weaver’s beam, or on to a sectional beam is direct or beam warping.
|number of warp yarns||3360|
|Number of warp beams||3360/560 = 6
(total number of warp yarns/creel capacity)
Indirect or sectional warping system
In Indirect or Sectional Warping System, several sections are wound in sequence and parallel to each other on a drum. Drop wire is a metal piece that falls and hits an electrode bar in case warp yarn breaks and stops the loom. Heald eye is a part of heald through which each warp yarn is threaded. This allows the movement of each warp yarn to be controlled during weaving. Reed dent is the opening in the reed. Reed beats the newly laid weft yarns into the body of the cloth.
The number of dents per unit width of reed called Reed count or reed number, they are denoted in the following way:
- The number of dents per inch
- The number of dents per 2 inch
- The number of groups of 20 dents per 36 inches
- The number of dents per 10 cm
- The recommended unit is dents/cm.
What is Selvedge?
Selvedge is the woven edge portion of a fabric parallel to the warp edge. It is a firmer construction than rest of the fabric that provides neat edge and a secure grip for fininshing machines.
Usually the selvedge has an increased number of ends per inch. Selvedges may contain special effects or brand names or fabric descriptions woven into them.
Types of selvedges
- Tuck-in selvedge:
Tuck-in selvedge is formed by tucking-in protruding portions of each pick into the next warp shed, alongside the new pick, and beating them up together with it.
- Double-pick interwoven selvedge:
Double-pick interwoven selvedge is formed by interweaving a strong selvedge end with the legs of the protruding loops, using a small reciprocating shuttle.
- Fused selvedge:
Fused selvedge is the thermoplastic warp and weft that are welded together by heat and pressure.
- Helical selvedge:
Helical selvedge is formed by nipping each pick between two strong, highly tensioned ends which interwine continuously, each end having a helical configuration.
- Inserted selvedge:
Inserted selvedgeis formed by inserting additional short double picks of strong fine yarn by means of a reciprocating needle.
- Leno selvedge:
Leno selvedge is formed by one or more pairs of strong, highly tensioned ends that interface with the weft on the leno principle. Warp threads are crossed and interwoven into the edges of the fabric.
- Traditional selvedge:
Traditional selvedge is formed without making special provision on a shuttle loom weaving plain cloth.