General terms of knitting technology
Machine knitting
Knitted structures are progressively built-up from row after row of intermeshed loops. The newly-fed yarn is converted into a new loop in each needle hook. The needle then draws the new loop head first through the old (fabric) loop, which it has retained from the previous knitting cycle. The needles, at the same time, release, (cast-off or knock-over) the old loops so that they hang suspended by their heads from the feet of the new loops whose heads are still held in the hooks of the
needles. A cohesive knitted loop structure is thus produced by a combination of the intermeshed needle loops and yarn that passes from needle loop to needle loop.
The knitted loop structure
The knitted loop structure may not always be noticeable because of the effect of structural fineness, fabric distortion, additional pattern threads or the masking effect of finishing processes. However, unless the intermeshing of the loops is securely achieved by the needles receiving new loops of yarn into their hooks before the old loops are ‘cast-off’, and the ground structure is not fractured during finishing or wear, a breakdown or separation of the structure will result.
Knitted loops are arranged in rows, roughly equivalent to the weft and warp of woven structures. These are termed ‘courses’ and ‘wales’ respectively.
A course
A course is a predominantly horizontal row of needle loops (in an upright fabric as knitted) produced by adjacent needles during the same knitting cycle. (The last five words help to prevent confusion when describing complex weft knitted fabrics).
A course length
In weft knitted fabrics (with the exception of structures such as jacquard, intarsia and warp insertion), a course of loops is composed of a single length of yarn termed a course length. Weft knitted structures will unrove from the course knitted last unless it is secured, for example, by binding-off.
A pattern row
A pattern row is a horizontal row of needle loops produced by adjacent needles in one needle bed. In plain weft knitted fabric this is identical to a course but in more complex fabrics a pattern row may be composed of two or more course lengths. In warp knitting, every loop in a course is usually composed of a separate yarn.
A wale
A wale is a predominantly vertical column of intermeshed needle loops generally produced by the same needle knitting at successive (not necessarily all) knitting cycles.A wale commences as soon as an empty needle starts to knit.
• When loop transfer occurs it is possible to transfer a wale of loops from one needle A to another B and to recommence knitting with the second needle, in which case more than one needle will have produced intermeshed loops in the same wale.
• In warp knitting a wale can be produced from the same yarn if the same warp guide laps the same needle at successive knitting cycles.
• Wales are connected together across the width of the fabric by sinker loops (weft knitting) or underlaps (warp knitting).
• Wales show most clearly on the technical face and courses on the technical back
of single needle bed fabric.
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| Picture - Course and wale of a weft knit fabric |
Stitch density
Stitch density refers to the total number of loops in a measured area of fabric and not to the length of yarn in a loop (stitch length). It is the total number of needle loops in a given area (such as a square inch, or three square centimetres).The figure is obtained by counting the number of courses or pattern rows in one inch (or three centimetres) and the number of wales in one inch (or three centimetres), then multiplying the number of courses by the number of wales. (Using a measurement of three centimetres rather than one, is preferable for accuracy in counting).
Stitch density gives a more accurate measurement than does a linear measurement of only courses or only wales. Tension acting in one direction might produce a low reading for the courses and a high reading for the wales; when they are multiplied together this effect is cancelled out. Pattern rows rather than courses may be counted when they are composed of a constant number of courses.
Technically upright
A knitted fabric is technically upright when its courses run horizontally and its wales run vertically, with the heads of the needle loops facing towards the top of the fabric and the course knitted first situated at the bottom of the fabric.
Design appearance requirements
The terms technical face, technical back, and upright are purely technically descriptive terms. They do not necessarily indicate the orientation of the fabric from the designer’s viewpoint.
For example:
• Socks and ladies hosiery are usually worn upside-down compared to their sequence of production.
• The technical back of structures is often used for plush and pile effects.
• Curtains may be hung sideways compared to the wales.
• Diagonal stripes may be achieved for dress-wear by cutting the fabric at an
angle.
