Textile Engineering Information

Knitting

 

To form a fabric by the intermeshing of loops of yarn.

 

Knitting is the method of creating fabric by transforming continuous strands of yarn into a series of interlocking loops, each raw of such loops hanging from the one immediately preceding it. Interloping consists of which is typically only released after a succeeding loop has been formed and achieved. The loops are also held together by the yarn passing from one to the next. Knitting is the most common method of interloping and is second only to weaving

as a method of manufacturing textile products. It is estimated that over 7 million tons of knitted goods are produced annually throughout the world.

 

Knitting is two types

A)    Warp Knitting

B)    Weft Knitting

 

Weft Knitting

Loops are formed by needles knitting the yarn across the width of the fabric. Each weft thread is fed at right angles to the direction of fabric formation. All stitches in a course are made by one yarn. Weft knit are made as either flat or open width fabrics (like woven fabrics) on so called flat knitting machine or as tubular fabrics (like a seamless stocking) on Circular knitting machine. In Circular knitting machine cam are still or fixed but Needle are moving.

 

The basic types of fabric used in weft knitting are the Jersey, the Rib and the Purl. Each of these fabric types is unique in appearance and from a function standpoint. All textile fabrics of weft knit construct are made from these basic types.

Warp Knitting

Loops are formed by needles knitting a series of warp yarns fed parallel to the direction of fabric formation. Usually warp knitted fabrics are made on a Flat knitting machine. In Flat knitting machine cam are moving but Needle are fixed or still.

 

Warp knitted fabric s are classified into two main categories, Tricots (pronounced Tree-ko) and several minor categories including simplex and Milanese.

 

 

Basic mechanical principles of

knitting technology

 

The sinker

The sinker is the second primary knitting element (the needle being the first). It is a thin metal plate with an individual or a collective action operating approximately at  right  angles  from  the  hook  side  of  the  needle  bed, between  adjacent  needles. It may perform one or more of the following functions, dependent upon the machine's knitting action and consequent sinker shape and movement:

 

Loop formation

Holding-down

Knocking-over

 

Basic Weft and Warp Knitting Terminology

 

Course: - The row of loops or stitches running across the width of a fabric. Corresponding to filling of a woven fabric.

 

Wales: - In knitted fabrics a column of loops running lengthwise the fabric.

 

Course Count: - The number of courses in a knit fabric per unit length measure. For example:  courses per inch.

 

Wale Count: - The number of wales in a knit fabric per unit length. For example:  Wales per inch.

 

Knit Loop: - A stitch in a knit fabric the yarn is formed into a loop shape by the knitting elements.  Knitting meshes or interlocks these loops to form a fabric.

 

Face Loop: - A knitted loop formed on the cylinder needles on a knitted machine.

 

Back Loop: - A knitted loop formed on the dial needles on a knitted machine.

 

Stitch: - In knitting a stitch is the loop geometry of a particular pattern repeat. It may be in the form of a knitted, a tuck or a float loop.

 

Tuck Loop: - A knitted stitch when a needle receives a new yarn without losing its old loop.

 

Float Loop: - A knitted stitch when a needle holds its old loop and does not receive a new yarn. It connects two loops on the same course but not in adjacent Wales. Also called miss-loop.

 

Yield: - The amount of fabric delivered off a knitting machine in terms of its weight per unit length or area, or the number of linear units delivered per unit weight. For example, ounces per yard's or ounces per square yard or yards per pound.

 

Course Length - The amount of yarn used in forming all the knit loops in one course of

a knitted fabric. Also called run-in.

 

Cut or Gauge: - The number of needles per inch in the circumference of the cylinder or dial of a knitting machine.

 

Gaiting:-The spacing of the needles in the dial and the cylinder in relation to each other on rib and interlock machines. In rib knitting, the needles of the cylinder are between the needles of the dial.   In interlock gaiting, the needles of the cylinder are directly opposed to the needles in the dial (opposed to each other).

 

Timing:- The  order  the  needles  in  the  dial  and  cylinder  go  through  the  knitting cycle  in  relationship  to  one another.   The cylinder needles that correspond to dial needle may go through the knitting cycle before or after the dial needle

 

Dial Height - The distance between the bottom edges of the dial section on a hitting machine at its perimeter from 'the corresponding upper edge of the cylinder at its perimeter.

 

Tricot - Type  of  warp  knitting  in  which  spring  beard’ed  needles  are  normally  used to make fine fabrics with usually one to three warps are used.

 

Raschel - A type of warp knitting in which plain and jacquard fabrics can be made. Raschel  fabrics  are  normally  coarser  than  other  types  of  warp  knits,  but  a  wide range of fabrics can be made.  Raschel machines may have one or two sets of needles and up to thirty guide bars.

 

 

 

Gauge - The number  of  needles  per  linear inch  of  the  needle bar. For most warp knits that refers to a one linear inch, but can be for two.

 

Needle  Bar - A  flat  metal  plate  with  slots  (tricks) cut  into  it  at  regular  interval’s  into which needles slide during the knitting process.

 

Runner Length - In warp knitting the number of inches of yarn needed to knit one rack of fabric.

 

Rack - A warp knitting measure of 480 courses.  Tricot fabric quality is judged by the number of inches per rack.

 

Inch quality: - A measure of quality of warp knit fabric. The number of inches’ of fabric per inch.

 

Full Set - A term that indicates that all guide eyes in a guide bar each have a yarn-from the warp.

 

Part  Set -  A term that  indicates that all guide eyes in  a guide bar do not have a yarn from  the  warp.

 

Positive Feed - When the yarn is metered off the warp beam by a metering device. Needles during the loop forming step.

 

Pattern  Wheel -  A  cylinder  or  wheel  upon  which  a  pattern  chain  is placed  which has links of different heights so as to move the guide bars throughout its pattern.