Principles of Machine Knitting

A knitted fabric is produced by interlooping yarns of one yarn set. Yarns, which are flexible, are formed into loops and then the newly formed loops are interconnected (meshed) with knitted loops (previous loops). Generally in a weft knitted fabric all the stitches in a course are formed from the same yarn, and therefore in a weft knitted fabric the yarns are in the direction of the courses. On the other hand in a warp knitted fabric the stitches in a course are formed with different yarns. In fact each knitting needle is provided with a separate yarn (this is the minimum requirement, on commercial fabrics each needle is provided with at least two yarn ends). Therefore in warp knitted fabrics the yarns are in the direction of the wales, i.e. parallel to the fabric selvedges.

Weft knitted structure Warp knitted structure

In machine knitting the interlooping of yarns is realised with various mechanical elements termed knitting elements. The knitting elements are manufactured to a very high degree of precision using high quality metals, in order to guarantee the production of quality knitted fabrics. In machine knitting the interlooping of yarns is achieved in steps. These steps are called knitting steps. To form a new stitch all the knitting steps have to be carried out in the correct sequence. The correct sequence of the knitting steps is known as the knitting cycle. In weft knitting a yarn is laid on to the needles individually with a yarn feeder or a yarn carrier, while in warp knitting every needle is provided with a yarn by using a knitting element called yarn guide. Thus in knitting as in weaving the yarn has to be provided to the knitting zone, and this is considered as the first knitting step. This step is known as yarn laying. Loops need to be formed form the newly provided yarn, and then they can be interconnected with knitted loops in the needles. As such another important knitting step is the loop formation, and the final step of a knitting cycle is the linking up step, in which the newly formed yarn loops are drawn through the knitted loop in the needles converting the yarn loops into knitted loops and knitted loops into new stitches. However, before the newly formed yarn loops can be pulled through the knitted loops the needle hooks, which had to be opened to accommodate the new yarn loops in them, must be closed before the yarn loops can be connected to knitted loops. This very important step in forming stitches is called bridge formation. The described steps are the most important fundamental steps of machine knitting, and they are common to all the different knitting techniques available at present, and therefore these are known as Primary Knitting Steps. The order in which these are carried out will depend on the knitting technique and the knitting needle.

III Answer the questions

1. What two sectors of knitting industry are mentioned in the text?

2. How many sets of yarn are used at weft knitting?

3. How does yarn travel at weft knitting?

4. What is the difference in stitch formation at weft and warp knitting?

5. What materials are knitting elements made from?

6. What are the Primary Knitting Steps?

IV Complete the table with the information from the text

	Weft knitting	Warp knitting
Number of yarn sets
Direction of the yarn
Yarn laying device

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